Epilepsia y desigualdad: descripción demográfica y análisis de la dificultad para el acceso a recursos avanzados en una población de un área de salud pequeña / Epilepsy and inequality: demographic description and analysis of the difficulty in accessing advanced resources in a population in a small health area

Introducción: La epilepsia es una enfermedad neurológica muy frecuente que implica una elevada morbimortalidad. La epilepsia farmacorresistente (EFR) supone un desafío terapéutico superior, incluso para expertos en la materia. A pesar de ello, el acceso a recursos avanzados para este tipo de pacientes continúa siendo dificultoso y desigual. El objetivo de este estudio es analizar la desigualdad en una población perteneciente a un hospital de primer nivel. Pacientes y métodos Se llevó a cabo un estudio transversal observacional analítico con pacientes epilépticos que acuden a consultas de neurología del área IX del Servicio Murciano de Salud. Se describen variables demográficas, clínicas, terapéuticas, pronósticas y de equidad, y se analizan diferencias significativas entre distintos subgrupos. Resultados En el estudio se incluyó a 68 pacientes con una media de edad de 42,93 años. El tipo de epilepsia principal fue la focal (64,7%), y los fármacos más usados fueron el levetiracetam (33,8%), el ácido valproico (27,9%) y la lamotrigina (22,1%). La EFR se dio en 18 pacientes (el 26,5% del total) y sólo cuatro se encontraban en seguimiento activo en una unidad de epilepsia, lo que implica que el 71% no accedía a un recurso necesario (advanced therapeutic gap). Conclusiones Este estudio demuestra que la desigualdad en la epilepsia continúa siendo un problema, especialmente en ciertas áreas geográficas, con una falta de acceso a atención avanzada en pacientes que más lo necesitan. La solución puede conseguirse aumentando recursos humanos y materiales que mejoren la atención global del paciente, reforzando así tanto los hospitales de referencia como las unidades de epilepsia. (AU)

INTRODUCTION: Epilepsy is a very common neurological disease with high morbidity and mortality. Drug-resistant epilepsy (DRE) poses a major therapeutic challenge, even for experts in the field. Despite this, access to advanced resources for this type of patient remains difficult and unequal. The aim of this study is to analyse inequality in a population belonging to a first level hospital. PATIENTS AND METHODS An analytical observational cross-sectional study was conducted on epileptic patients attending neurology consultations in Area IX of the Murcian Health Service. Demographic, clinical, therapeutic, prognostic and equity variables are described, and significant differences between different subgroups are analysed. RESULTS The study included 68 patients with a mean age of 42.93 years. Focal epilepsy was the main type (64.7%), and the most commonly used drugs were levetiracetam (33.8%), valproic acid (27.9%) and lamotrigine (22.1%). DRE occurred in 18 patients (26.5% of the total) and only four were under active follow-up in an epilepsy unit, meaning that 71% did not have access to a necessary resource (advanced therapeutic gap). CONCLUSIONS This study demonstrates that epilepsy inequality continues to be a problem, especially in certain geographical areas, with a lack of access to advanced care for patients who need it most. The solution can be achieved by increasing human and material resources to improve overall patient care, thus strengthening both referral hospitals and epilepsy units. (AU)

[Epilepsy and inequality: demographic description and analysis of the difficulty in accessing advanced resources in a population in a small health area]. / Epilepsia y desigualdad: descripción demográfica y análisis de la dificultad para el acceso a recursos avanzados en una población de un área de salud pequeña.

INTRODUCTION: Epilepsy is a very common neurological disease with high morbidity and mortality. Drug-resistant epilepsy (DRE) poses a major therapeutic challenge, even for experts in the field. Despite this, access to advanced resources for this type of patient remains difficult and unequal. The aim of this study is to analyse inequality in a population belonging to a first level hospital. PATIENTS AND METHODS: An analytical observational cross-sectional study was conducted on epileptic patients attending neurology consultations in Area IX of the Murcian Health Service. Demographic, clinical, therapeutic, prognostic and equity variables are described, and significant differences between different subgroups are analysed. RESULTS: The study included 68 patients with a mean age of 42.93 years. Focal epilepsy was the main type (64.7%), and the most commonly used drugs were levetiracetam (33.8%), valproic acid (27.9%) and lamotrigine (22.1%). DRE occurred in 18 patients (26.5% of the total) and only four were under active follow-up in an epilepsy unit, meaning that 71% did not have access to a necessary resource (advanced therapeutic gap). CONCLUSIONS: This study demonstrates that epilepsy inequality continues to be a problem, especially in certain geographical areas, with a lack of access to advanced care for patients who need it most. The solution can be achieved by increasing human and material resources to improve overall patient care, thus strengthening both referral hospitals and epilepsy units.

TITLE: Epilepsia y desigualdad: descripción demográfica y análisis de la dificultad para el acceso a recursos avanzados en una población de un área de salud pequeña.Introducción. La epilepsia es una enfermedad neurológica muy frecuente que implica una elevada morbimortalidad. La epilepsia farmacorresistente (EFR) supone un desafío terapéutico superior, incluso para expertos en la materia. A pesar de ello, el acceso a recursos avanzados para este tipo de pacientes continúa siendo dificultoso y desigual. El objetivo de este estudio es analizar la desigualdad en una población perteneciente a un hospital de primer nivel. Pacientes y métodos. Se llevó a cabo un estudio transversal observacional analítico con pacientes epilépticos que acuden a consultas de neurología del área IX del Servicio Murciano de Salud. Se describen variables demográficas, clínicas, terapéuticas, pronósticas y de equidad, y se analizan diferencias significativas entre distintos subgrupos. Resultados. En el estudio se incluyó a 68 pacientes con una media de edad de 42,93 años. El tipo de epilepsia principal fue la focal (64,7%), y los fármacos más usados fueron el levetiracetam (33,8%), el ácido valproico (27,9%) y la lamotrigina (22,1%). La EFR se dio en 18 pacientes (el 26,5% del total) y sólo cuatro se encontraban en seguimiento activo en una unidad de epilepsia, lo que implica que el 71% no accedía a un recurso necesario (advanced therapeutic gap). Conclusiones. Este estudio demuestra que la desigualdad en la epilepsia continúa siendo un problema, especialmente en ciertas áreas geográficas, con una falta de acceso a atención avanzada en pacientes que más lo necesitan. La solución puede conseguirse aumentando recursos humanos y materiales que mejoren la atención global del paciente, reforzando así tanto los hospitales de referencia como las unidades de epilepsia.

Caracterización organoléptica, nutricional, microbiológica y digestibilidad in vitro de ensilados con diferentes niveles de inclusión de desperdicios de alimentos / Organoleptic, nutritional, microbiological characterization and in vitro digestibility of silage with different levels of inclusion of food waste

RESUMEN Objetivo: caracterización organoléptica, nutricional, microbiológica y digestibilidad in vitro de ensilados de desperdicios de alimentos recolectados en un restaurante de un centro de estudios técnicos y tecnológicos con subproductos de cosecha. Metodología: se realizó un análisis organoléptico, microbiológico, proximal de la composición y digestibilidad in vitro de ensilajes con diferentes niveles de inclusión de desperdicios de alimentos. Resultados: se evidencian características de olor, color y textura óptimas para su palatabilidad, valores nutricionales favorables para el 30, 35 y 40% de inclusión de desperdicios, bajos promedios de proteína, pero con niveles de energía superiores a los del maíz, sorgo y soya. La digestibilidad in vitro de la materia seca (DIVMS) fue mejor para el 35% de inclusión. Así mismo, la Unidad Formadora de Colonias UFC/g para el día 21 fue 1 x10 (Escherichia coli), que se ajusta a las normas para alimentos de animales. Conclusiones: la utilización de ensilados con un 35% de inclusión de desperdicios de alimento puede ser una importante herramienta de suplementación para la alimentación porcina.

ABSTRACT Aim: characterize organoleptic, nutritional, microbiological and in vitro digestibility of food waste silage collected in a restaurant of a technical and technological studies center with harvest by-products. Metodology: it has been make organoleptic analysis, microbiologic, proximal composition, in vitro digestibility of silages with different levels of inclusion of food waste. Results: it is evidenced characteristics of smell, color and texture optimal so as to palatability, favorable nutritional values for 30, 35 and 40% inclusion of waste, low protein levels, but with hight energy levels superior to corn, sorghum and soybeans. The dry mater in vitro digestibility in vitro de la materia seca (DIVMS) was better for 35% inclusión. Moreover, In addition, the UFC/g colony forming units for 21th day was 1 X101 (Escherichia coli), that conforms to the standards for animal feed. Conclusions: to use silages with 35% inclusion of food waste may be one important tool of supplementation for swine feeding.

Altered circadian feeding behavior and improvement of metabolic syndrome in obese Tac1-deficient mice.

BACKGROUND: Metabolic function is regulated by the interplay of central and peripheral factors that ultimately regulate food intake (FI) and energy expenditure. The tachykinin substance P (SP) has been identified as a novel regulator of energy balance, however, the mechanisms underlying this effect are ill-defined and conflicting data regarding the role of SP on FI have been reported by different groups. OBJECTIVE: To further characterize the metabolic role of the Tac1 gene products (SP and neurokinin A) in mice through a series of genetic, metabolic and behavioral studies in Tac1-deficient mice. RESULTS: Tac1-/- mice are leaner than controls and display reduced FI and altered feeding circadian rhythm, supported by disrupted expression of the clock genes Cry1/2, Per1/2 in the suprachiasmatic nucleus, mediobasal hypothalamus (MBH) and liver, as well as increased proopiomelanocortin expression in the MBH. Tac1 ablation induced resistance to obesity, improved glucose tolerance, prevented insulin resistance under high-fat diet, increased activation of brown adipose tissue and improved hepatic steatosis. Moreover, deletion of Tac1 in ob/ob mice ameliorated body weight gain in females only but was sufficient to decrease fat and triglyceride content in the liver of males. CONCLUSIONS: These results provide further evidence that Tac1 controls circadian feeding behavior and metabolism in mice through mechanisms that involve the regulation of the melanocortin system. In addition, these studies suggest that the blockade of SP may offer a new method to treat metabolic syndrome.

Effects and interactions of tachykinins and dynorphin on FSH and LH secretion in developing and adult rats.

Kisspeptin/neurokinin B/dynorphin (KNDy) neurons, which coexpress kisspeptins (Kps), neurokinin B (NKB), and dynorphin (Dyn), regulate gonadotropin secretion. The KNDy model proposes that NKB (a stimulator, through NK3R) and Dyn (an inhibitor, through κ-opioid receptor) shape Kp secretion onto GnRH neurons. However, some aspects of this paradigm remain ill defined. Here we aimed to characterize the following: 1) the effects of NKB signaling on FSH secretion and 2) the role of Dyn in gonadotropin secretion after NK3R activation; 3) additionally, we explored the roles of other tachykinin receptors, NK1R and NK2R, on gonadotropin release. Thus, the effects of the NK3R agonist, senktide, on FSH release were explored across postnatal development in male and female rats; gonadotropin responses to agonists of NK1R substance P and NK2R [neurokinin A (NKA)] were also monitored. Moreover, the effects of senktide on gonadotropin secretion were assessed after antagonizing Dyn actions by nor-binaltorphimine didydrochloride. Before puberty, rats of both sexes showed increased FSH secretion to senktide (and Kp-10). Conversely, adult female rats were irresponsive to senktide in terms of FSH, despite proven LH responses, whereas the adult males did not display FSH or LH responses to senktide, even at high doses. In turn, substance P and NKA stimulated gonadotropin secretion in prepubertal rats, whereas in adults modest gonadotropin responses to NKA were detected. By pretreatment with a Dyn antagonist, adult males became responsive to senktide in terms of LH secretion and displayed elevated basal LH and FSH levels; nor-binaltorphimine didydrochloride treatment uncovered FSH responses to senktide in adult females. Furthermore, the expression of Pdyn and Opkr1 (encoding Dyn and κ-opioid receptor, respectively) in the mediobasal hypothalamus was greater in males than in females at prepubertal ages. Overall, our data contribute to refining our understanding on how the elements of the KNDy node and related factors (ie, other tachykinins) differentially participate in the control of gonadotropins at different stages of rat postnatal maturation.

Changes in hypothalamic expression of the Lin28/let-7 system and related microRNAs during postnatal maturation and after experimental manipulations of puberty.

Lin28 and Lin28b are related RNA-binding proteins that inhibit the maturation of miRNAs of the let-7 family and participate in the control of cellular stemness and early embryonic development. Considerable interest has arisen recently concerning other physiological roles of the Lin28/let-7 axis, including its potential involvement in the control of puberty, as suggested by genome-wide association studies and functional genomics. We report herein the expression profiles of Lin28 and let-7 members in the rat hypothalamus during postnatal maturation and in selected models of altered puberty. The expression patterns of c-Myc (upstream positive regulator of Lin28), mir-145 (negative regulator of c-Myc), and mir-132 and mir-9 (putative miRNA repressors of Lin28, predicted by bioinformatic algorithms) were also explored. In male and female rats, Lin28, Lin28b, and c-Myc mRNAs displayed very high hypothalamic expression during the neonatal period, markedly decreased during the infantile-to-juvenile transition and reached minimal levels before/around puberty. A similar puberty-related decline was observed for Lin28b in monkey hypothalamus but not in the rat cortex, suggesting species conservation and tissue specificity. Conversely, let-7a, let-7b, mir-132, and mir-145, but not mir-9, showed opposite expression profiles. Perturbation of brain sex differentiation and puberty, by neonatal treatment with estrogen or androgen, altered the expression ratios of Lin28/let-7 at the time of puberty. Changes in the c-Myc/Lin28b/let-7 pathway were also detected in models of delayed puberty linked to early photoperiod manipulation and, to a lesser extent, postnatal underfeeding or chronic subnutrition. Altogether, our data are the first to document dramatic changes in the expression of the Lin28/let-7 axis in the rat hypothalamus during the postnatal maturation and after different manipulations that disturb puberty, thus suggesting the potential involvement of developmental changes in hypothalamic Lin28/let-7 expression in the mechanisms permitting/leading to puberty onset.

Neurokinin B and the control of the gonadotropic axis in the rat: developmental changes, sexual dimorphism, and regulation by gonadal steroids.

Neurokinin B (NKB), encoded by Tac2 in rodents, and its receptor, NK3R, have recently emerged as important regulators of reproduction; NKB has been proposed to stimulate kisspeptin output onto GnRH neurons. Accordingly, NKB has been shown to induce gonadotropin release in several species; yet, null or even inhibitory effects of NKB have been also reported. The basis for these discrepant findings, as well as other key aspects of NKB function, remains unknown. We report here that in the rat, LH responses to the NK3R agonist, senktide, display a salient sexual dimorphism, with persistent stimulation in females, regardless of the stage of postnatal development, and lack of LH responses in males from puberty onward. Such dimorphism was independent of the predominant sex steroid after puberty, because testosterone administration to adult females failed to prevent LH responses to senktide, and LH responsiveness was not restored in adult males treated with estradiol or the nonaromatizable androgen, dihydrotestosterone. Yet, removal of sex steroids by gonadectomy switched senktide effects to inhibitory, both in adult male and female rats. Sexual dimorphism was also evident in the numbers of NKB-positive neurons in the arcuate nucleus (ARC), which were higher in adult female rats. This is likely the result of differences in sex steroid milieu during early periods of brain differentiation, because neonatal exposures to high doses of estrogen decreased ARC NKB neurons at later developmental stages. Likewise, neonatal estrogenization resulted in lower serum LH levels that were normalized by senktide administration. Finally, we document that the ability of estrogen to inhibit hypothalamic Tac2 expression seems region specific, because estrogen administration decreased Tac2 levels in the ARC but increased them in the lateral hypothalamus. Altogether, our data provide a deeper insight into relevant aspects of NKB function as major regulator of the gonadotropic axis in the rat, including maturational changes, sexual dimorphism, and differential regulation by sex steroids.

Regulation of NKB pathways and their roles in the control of Kiss1 neurons in the arcuate nucleus of the male mouse.

Kisspeptin (Kiss1) and neurokinin B (NKB) (encoded by the Kiss1 and Tac2 genes, respectively) are indispensable for reproduction. In the female of many species, Kiss1 neurons in the arcuate nucleus (ARC) coexpress dynorphin A and NKB. Such cells have been termed Kiss1/NKB/Dynorphin (KNDy) neurons, which are thought to mediate the negative feedback regulation of GnRH/LH secretion by 17ß-estradiol. However, we have less knowledge about the molecular physiology and regulation of Kiss1/Kiss1-expressing neurons in the ARC of the male. Our work focused on the adult male mouse, where we sought evidence for coexpression of these neuropeptides in cells in the ARC, assessed the role of Kiss1 neurons in negative feedback regulation of GnRH/LH secretion by testosterone (T), and investigated the action of NKB on KNDy and GnRH neurons. Results showed that 1) the mRNA encoding Kiss1, NKB, and dynorphin are coexpressed in neurons located in the ARC; 2) Kiss1 and dynorphin A mRNA are regulated by T through estrogen and androgen receptor-dependent pathways; 3) senktide, an agonist for the NKB receptor (neurokinin 3 receptor, encoded by Tacr3), stimulates gonadotropin secretion; 4) KNDy neurons express Tacr3, whereas GnRH neurons do not; and 5) senktide activates KNDy neurons but has no discernable effect on GnRH neurons. These observations corroborate the putative role for KNDy neurons in mediating the negative feedback effects of T on GnRH/LH secretion and provide evidence that NKB released from KNDy neurons is part of an auto-feedback loop that generates the pulsatile secretion of Kiss1 and GnRH in the male.

Persistent impairment of hypothalamic KiSS-1 system after exposures to estrogenic compounds at critical periods of brain sex differentiation.

Attainment of reproductive capacity at puberty relies on a complex series of maturational events that include sexual differentiation of the brain; a hormonally driven phenomenon that takes place at early stages of development (critical period). Alterations of sex steroid milieu during such critical period disrupt pubertal maturation and gonadotropic function later in life, through mechanisms that remain partially unknown. Kisspeptins, products of the KiSS-1 gene acting via G protein-coupled receptor 54, have recently emerged as essential gatekeepers of puberty onset and reproductive function. By using rat models of neonatal administration of estrogenic compounds, we provide herein compelling evidence for the functional impairment of the hypothalamic KiSS-1 system at the time preceding puberty after early inappropriate exposures during brain sex differentiation. Neonatal injection of estradiol benzoate to male and female rats resulted in a dose-dependent decrease in hypothalamic KiSS-1 mRNA levels at the prepubertal stage, linked to lowering of serum LH concentrations. Yet, despite persistently decreased basal gonadotropin levels in estrogenized animals, intracerebral injection of kisspeptin evoked potent LH and FSH secretory responses, similar in magnitude to those of control animals. Estrogenized rats also showed defective levels of hypothalamic KiSS-1 mRNA and circulating gonadotropins in response to gonadectomy, whereas exogenous kisspeptin was capable to enhance further LH and FSH secretion in this model. Finally, protocols of neonatal exposure to high doses of an environmentally relevant estrogen, bisphenol-A, mimicked the effects of estradiol benzoate in terms of hypothalamic expression of KiSS-1 gene at the prepubertal period. Altogether, our data document the sensitivity of the hypothalamic KiSS-1 system to alterations in sex steroid milieu during critical periods of brain sex differentiation, and suggest that lowering of endogenous kisspeptin tone induced by early exposures to xeno-estrogens might be mechanistically relevant for disruption of gonadotropin secretion and puberty onset later in life.

Kisspeptins and the control of gonadotropin secretion in male and female rodents.

Kisspeptins, the products of KiSS-1 gene acting via G protein-coupled receptor 54 (GPR54), have recently emerged as fundamental gatekeepers of gonadal function by virtue of their ability to stimulate gonadotropin secretion. Indeed, since the original disclosure of the reproductive facet of the KiSS-1/GPR54 system, an ever-growing number of studies have substantiated the extraordinary potency of kisspeptins to elicit gonadotropin secretion in different mammalian species, under different physiologic and experimental conditions, and through different routes of administration. In this context, studies conducted in laboratory rodents have been enormously instrumental to characterize: (i) the primary mechanisms of action of kisspeptins in the control of gonadotropin secretion; (ii) the pharmacological consequences of acute vs. continuous activation of GPR54; (iii) the roles of specific populations of kisspeptin-producing neurons at the hypothalamus in mediating the feedback effects of sex steroids; (v) the function of kisspeptins in the generation of the pre-ovulatory surge of gonadotropins; and (iv) the influence of sex steroids on GnRH/gonadotropin responsiveness to kisspeptins. While some of those aspects of kisspeptin function will be covered elsewhere in this Special Issue, we summarize herein the most salient data, obtained in laboratory rodents, that have helped to define the physiologic roles and putative pharmacological implications of kisspeptins in the control of male and female gonadotropic axis.

Alterations in hypothalamic KiSS-1 system in experimental diabetes: early changes and functional consequences.

Using long-term streptozotocin (STZ)-treated male rats, we recently proposed that defective function of hypothalamic KiSS-1 system is mechanistically relevant for central hypogonadotropism of uncontrolled diabetes. However, the temporal pattern of such defects and its potential contribution to disturbed gonadotropin secretion in the diabetic female remain so far unexplored. To cover these issues, expression analyses and hormonal tests were conducted in diabetic male (1 wk after STZ; short term) and female (4 wk after STZ; long term) rats. Short-term diabetic males had lower basal testosterone levels and decreased gonadotropin responses to orchidectomy (ORX), which associated with significantly attenuated post-ORX rises of hypothalamic KiSS-1 mRNA. Yet kisspeptin administration to diabetic males was able to acutely elicit supramaximal LH and testosterone responses and normalize post-ORX gonadotropin secretion. Long-term diabetic females showed persistent anestrus and significantly decreased basal gonadotropin levels as well as blunted LH responses to ovariectomy; changes that were linked to lowering of basal and postovariectomy expression of hypothalamic KiSS-1 mRNA. Moreover, despite prevailing gonadotropin suppression, LH responses to acute kisspeptin administration were fully preserved, and even enhanced after its repeated injection, in diabetic females. In sum, our present findings further define the temporal course and mechanistic relevance of altered hypothalamic KiSS-1 system in the hypogonadotropic state of uncontrolled diabetes. Furthermore, our data provide the basis for the potential therapeutic intervention of the KiSS-1 system as adjuvant in the management of disturbed gonadotropin secretion of type 1 diabetes in the female.

Follicle-stimulating hormone responses to kisspeptin in the female rat at the preovulatory period: modulation by estrogen and progesterone receptors.

Ovulation is triggered by the preovulatory surge of gonadotropins that, in rodents, is defined by the concomitant rise in circulating LH and FSH at the afternoon of proestrus (primary surge), followed by persistently elevated FSH levels at early estrus (secondary surge). In recent years, kisspeptins, products of the KiSS-1 gene that act via G protein-coupled receptor 54, have emerged as an essential hypothalamic conduit for the generation of the preovulatory LH surge by conveying positive feedback effects of estradiol onto GnRH neurons, an event that involves not only estradiol-induced transcription of the KiSS-1 gene at the anteroventral periventricular nucleus but also its ability to modulate GnRH/LH responses to kisspeptin. However, little is known about the potential modulation of FSH responsiveness to kisspeptin by sex steroids in the cyclic female. We report herein analyses on the consequences of selective blockade of estrogen receptors (ER)-alpha and -beta, as well as progesterone receptor (PR), on the ovulatory surges of FSH and their modulation by kisspeptin. Antagonism of ERalpha or PR equally blunted the primary and secondary surges of FSH and nullified FSH responses to kisspeptin at the preovulatory period. Conversely, selective blockade of ERbeta failed to induce major changes in terms of endogenous FSH surges, yet it decreased FSH responses to exogenous kisspeptin. In contrast, FSH responses to GnRH were fully conserved after ERbeta blockade and partially preserved after inhibition of ERalpha and PR signaling. Finally, secondary FSH secretion was rescued by kisspeptin in females with selective blockade of ERalpha but not PR. In sum, our results substantiate a concurrent, indispensable role of ERalpha and PR in the generation of FSH surges and the stimulation of FSH responses to kisspeptin at the ovulatory period. In addition, our data suggest that ERbeta might operate as a subtle, positive modulator of the preovulatory FSH responses to kisspeptin, a role that is opposite to its putative inhibitory action on kisspeptin-induced LH secretion and might contribute to the dissociation of gonadotropin secretion at the ovulatory phase in the cyclic female rat.

Desensitization of gonadotropin responses to kisspeptin in the female rat: analyses of LH and FSH secretion at different developmental and metabolic states.

Kisspeptins have emerged as potent elicitors of gonadotropin secretion and, therefore, putative targets for pharmacological intervention. In this context, desensitization of gonadotropin responses to continuous administration of kisspeptins has begun to be characterized, but information so far available is mostly restricted to LH responses in males, whereas the similar phenomenon in females, of obvious therapeutic interest, remains virtually unexplored. We report herein LH and FSH responses to continuous intracerebral administration of kisspeptin in female rats at different developmental and metabolic states. Infusion of kisspeptin-10 to adult female rats induced a transient elevation in serum LH concentrations, followed by a precipitous drop and normalization of LH levels thereafter. Elevation of LH after kisspeptin infusion was prolonged in underfed animals; a phenomenon mimicked by leptin administration. Conversely, FSH levels were persistently heightened along continuous kisspeptin infusion, but duration of this response was shortened by undernutrition. In pubertal females, LH and FSH levels remained elevated at the end of a 7-day infusion of kisspeptin; responses whose magnitude was augmented by subnutrition but not mimicked by leptin. In all settings, terminal gonadotropin-releasing hormone responses were fully preserved, suggesting that eventual desensitization must occur upstream from the pituitary. In summary, our current data document the pharmacological consequences of continuous administration of kisspeptin to female rats, with remarkable differences being detected between LH and FSH responses, in different developmental and metabolic states. These observations of potential pharmacological interest might help also to delineate the physiological roles of kisspeptins in the dynamic regulation of gonadotropin secretion in the female.

Opposite roles of estrogen receptor (ER)-alpha and ERbeta in the modulation of luteinizing hormone responses to kisspeptin in the female rat: implications for the generation of the preovulatory surge.

Ovulation is triggered by the preovulatory rise of gonadotropins, which is in turn elicited by the preceding increase in circulating estrogen. Kisspeptins, ligands of G protein-coupled receptor 54 encoded by the KiSS-1 gene, have emerged as potent stimulators of GnRH/LH secretion, and KiSS-1 neurons at the anteroventral periventricular nucleus have been shown to be involved in the generation of preovulatory LH surge, estrogen being a potent elicitor of KiSS-1 gene expression selectively at the anteroventral periventricular nucleus. Whether, in addition to transcriptional effects, estrogen influences other aspects of kisspeptin-induced GnRH/LH release in the female remains unexplored. We provide herein evidence for the specific roles of estrogen receptor (ER)-alpha and ERbeta in the modulation of LH responses to kisspeptin and the generation of the preovulatory surge. Selective blockade of ERalpha in cyclic females blunted LH responses to kisspeptin, eliminated the endogenous preovulatory rise of LH, and blocked ovulation. In contrast, antagonism of ERbeta failed to cause major changes in terms of LH surge and ovulatory rate but significantly augmented acute LH responses to kisspeptin. Notably, defective LH secretion and ovulation after ERalpha blockade were not observed after GnRH stimulation, which elicited maximal acute (<2 h) LH responses regardless of ERalpha/ERbeta signaling. In addition, net LH secretion in response to kisspeptin was decreased by ovariectomy and increased after selective activation of ERalpha but not ERbeta. Altogether, our data document the prominent positive role of ERalpha in the regulation of GnRH/LH responsiveness to kisspeptin and, thereby, ovulation. In addition, our results disclose the putative function of ERbeta as negative modifier of GnRH/LH response to kisspeptin, a phenomenon that might contribute to partially restraining LH secretion at certain physiological states.

Neuromedin s as novel putative regulator of luteinizing hormone secretion.

Neuromedin S (NMS), a 36 amino acid peptide structurally related to neuromedin U, was recently identified in rat brain as ligand for the G protein-coupled receptor FM4/TGR-1, also termed neuromedin U receptor type-2 (NMU2R). Central expression of NMS appears restricted to the suprachiasmatic nucleus, and NMS has been involved in the regulation of dark-light rhythms and suppression of food intake. Reproduction is known to be tightly regulated by metabolic and photoperiodic cues. Yet the potential contribution of NMS to the control of reproductive axis remains unexplored. We report herein analyses of hypothalamic expression of NMS and NMU2R genes, as well as LH responses to NMS, in different developmental and functional states of the female rat. Expression of NMS and NMU2R genes was detected at the hypothalamus along postnatal development, with significant fluctuations of their relative levels (maximum at prepubertal stage and adulthood). In adult females, hypothalamic expression of NMS (which was confined to suprachiasmatic nucleus) and NMU2R significantly varied during the estrous cycle (maximum at proestrus) and was lowered after ovariectomy and enhanced after progesterone supplementation. Central administration of NMS evoked modest LH secretory responses in pubertal and cyclic females at diestrus, whereas exaggerated LH secretory bursts were elicited by NMS at estrus and after short-term fasting. Conversely, NMS significantly decreased elevated LH concentrations of ovariectomized rats. In summary, we provide herein novel evidence for the ability of NMS to modulate LH secretion in the female rat. Moreover, hypothalamic expression of NMS and NMU2R genes appeared dependent on the functional state of the female reproductive axis. Our data are the first to disclose the potential implication of NMS in the regulation of gonadotropic axis, a function that may contribute to the integration of circadian rhythms, energy balance, and reproduction.

Ontogeny and mechanisms of action for the stimulatory effect of kisspeptin on gonadotropin-releasing hormone system of the rat.

Kisspeptins have recently emerged as essential regulators of gonadotropin secretion and puberty onset. These functions are primarily conducted by stimulation of hypothalamic gonadotropin-releasing hormone (GnRH) secretion. However, relevant aspects of KiSS-1 physiology, including the ontogeny and major signaling systems of its stimulatory action, remain to be fully elucidated. To cover these issues, the effects of kisspeptin-10 on GnRH and LH secretion were monitored at early stages of postnatal maturation, and potential changes in the sensitivity to kisspeptin were assessed along the pubertal transition in the rat. In addition, the signaling cascades involved in kisspeptin-induced GnRH secretion were explored by means of pharmacological blockade using rat hypothalamic explants. Despite sexual immaturity, kisspeptin-10 potently elicited GnRH release ex vivo and LH secretion in vivo at early stages (neonatal to juvenile) of postnatal development. Yet, LH responsiveness to low doses of kisspeptin was enhanced in peri-pubertal animals. Concerning GnRH secretion, the stimulatory action of kisspeptin-10 required activation of phospholipase-C, mobilization of intracellular Ca2+ and recruitment of ERK1/2 and p38 kinases, but was preserved after blockade of type 2 cyclo-oxygenase and prostaglandin synthesis. In summary, our present data document the ontogeny, sensitivity and intracellular signals for the stimulatory action of kisspeptin on the GnRH/LH axis in the rat. Although LH responses to low doses of kisspeptin appeared to be enhanced at puberty, kisspeptin was able to readily activate the GnRH system at early stages of postnatal maturation. These observations further stress the essential role of kisspeptin in normal, and eventually pathological, timing of puberty.

Expression of KiSS-1 in rat ovary: putative local regulator of ovulation?

Kisspeptins, the products of KiSS-1 gene, and their receptor, GPR54, have recently emerged as essential gatekeepers of reproduction, mainly through regulation of GnRH secretion at the hypothalamus. However, the profound hypogonadotropism linked to GPR54 inactivation is likely to mask additional functions of this system at other levels of the gonadal axis, in which expression of KiSS-1 and GPR54 has been preliminarily reported. We describe herein the expression of KiSS-1 gene and kisspeptin immunoreactivity (IR) in rat ovary and evaluate its developmental and hormonal regulation. KiSS-1 and GPR54 mRNAs were persistently detected in adult ovary along estrous cycle. Yet, contrary to GPR54, ovarian KiSS-1 levels fluctuated in a cyclic-dependent manner, with a robust increase in the afternoon of proestrus, i.e. preceding ovulation. In addition, kisspeptin-IR was observed in rat ovary, with strong signals in theca layers of growing follicles, corpora lutea, and interstitial gland, compartments in which modest GPR54-IR was also detected. Interestingly, the rise in ovarian KiSS-1 mRNA at proestrus was prevented by blockade of preovulatory gonadotropin surge and restored by replacement with human chorionic gonadotropin as superagonist of LH. In addition, immature ovaries showed low to negligible levels of KiSS-1 mRNA, which were significantly enhanced by gonadotropin priming. In summary, we present novel evidence for the developmental and hormonally regulated expression of the KiSS-1 gene, and the presence of kisspeptin-IR, in rat ovary. The ability of the LH surge to timely induce ovarian expression of KiSS-1 at the preovulatory period strongly suggests a previously unsuspected role of locally produced kisspeptin in the control of ovulation.

Effects of galanin-like peptide on luteinizing hormone secretion in the rat: sexually dimorphic responses and enhanced sensitivity at male puberty.

Reproductive function is exquisitely sensitive to adequacy of nutrition and fuel reserves, through mechanisms that are yet to be completely elucidated. Galanin-like peptide (GALP) has recently emerged as another neuropeptide link that couples reproduction and metabolism. However, although the effects of GALP on luteinizing hormone (LH) secretion have been studied, no systematic investigation on how these responses might differ along sexual maturation and between sexes has been reported. Moreover, the influence of metabolic status and potential interplay with other relevant neurotransmitters controlling LH secretion remain ill defined. These facets of GALP physiology were addressed herein. Intracerebral injection of GALP to male rats induced a dose-dependent increase in serum LH levels, the magnitude of which was significantly greater in pubertal than in adult males. In contrast, negligible LH responses to GALP were detected in pubertal or adult female rats at diestrus. Neonatal androgen treatment to females failed to "masculinize" the pattern of LH response to GALP. In addition, metabolic stress by short-term fasting did not prevent but rather amplified LH responses to GALP in pubertal males, whereas these responses were abrogated by pharmacological inhibition of nitric oxide synthesis. We conclude that the ability of GALP to evoke LH secretion is sexually differentiated, with maximal responses at male puberty, a phenomenon which was not reverted by manipulation of sex steroid milieu during the critical neonatal period and was sensitive to metabolic stress. This state of LH hyperresponsiveness may prove relevant for the mechanisms relaying metabolic status to the reproductive axis in male puberty.

Novel signals for the integration of energy balance and reproduction.

Although the close link between body weight and fertility has been known for eons, only recently have the peripheral signals and neuroendocrine networks responsible for such a phenomenon begun to be identified. A key event in this field was the cloning of the adipocyte-derived hormone leptin, which has been demonstrated as a pivotal regulator for the integration of energy homeostasis and reproduction. In addition, other metabolic hormones, such as insulin, contribute to this physiological integration. Moreover, compelling experimental evidence implicates hormonal products of the gastrointestinal tract as adjuncts in the complex coordination and regulation of body weight and reproduction. Here, we review recent studies evaluating the reproductive effects and sites of action of ghrelin and PYY3-36, two hormonal signals of gastrointestinal origin involved in the control food intake and energy balance. In addition, we summarize the potential contribution of kisspeptin, the recently characterized gatekeeper of the GnRH system encoded by Kiss1 gene, to integrating reproductive function and energy status. Evidence suggests that besides having direct gonadal effects, ghrelin may participate in the regulation of gonadotropin secretion and it may influence the timing of puberty. Likewise, PYY3-36 modulates GnRH and gonadotropin release. In addition, the hypothalamic KiSS-1 system is sensitive to nutritional status, and its diminished expression during states of negative energy balance might contribute to the suppression of reproductive function in such conditions. We propose that the peripheral hormones, ghrelin and PYY3-36, and the central neuropeptide, kisspeptin, are 'novel' players in the neuroendocrine networks that integrate energy balance and reproduction.

Effects of single or repeated intravenous administration of kisspeptin upon dynamic LH secretion in conscious male rats.

The ability of kisspeptins, ligands of the G protein-coupled receptor 54, to potently elicit LH secretion is now undisputed. Yet, most of the pharmacological characterization of their gonadotropin-releasing effects has been conducted after intracerebral administration. In contrast, the effects of peripheral injection of kisspeptin remains less well defined. In this study, dynamic LH secretory responses to iv administration of kisspeptin-10 in different experimental settings are presented, and compared with those evoked by kisspeptin-52, using a protocol of serial blood sampling in conscious, freely moving male rats. LH responsiveness to peripheral administration of kisspeptin appeared extremely sensitive, as doses as low as 0.3 nmol/kg (0.1 microg/rat) evoked robust LH bursts, the magnitude of which was dose-dependent and apparently maximal in response to 3.0 and 30 nmol/kg kisspeptin-10. The ability of kisspeptin-10 to stimulate LH release was fully preserved, and even doubled in terms of relative increases, after short-term fasting despite suppression of prevailing LH levels. Repeated injections of kisspeptin-10 (four boluses, at 75-min intervals) evoked associated LH secretory pulses, the magnitude of which remained constant along the study period. Moreover, in this setting, in vivo LH responses to a terminal injection of GnRH were preserved, whereas basal and depolarization-induced GnRH release ex vivo was significantly enhanced. Finally, iv administration of kisspeptin-52 elicited dynamic LH responses analogous to that of kisspeptin-10; yet, their net magnitude and duration was slightly greater. In summary, we present in this study a series of experiments on the effects of systemic (iv) injection of single or repeated doses of kisspeptin upon dynamic LH secretion in conscious male rats. Aside from potential physiologic relevance, our present data might contribute to setting the basis for the rational therapeutic use of kisspeptin analogs in the pharmacological manipulation of the gonadotropic axis.