Sonchus oleraceus L.: ethnomedical, phytochemical and pharmacological aspects.

Sonchus oleraceus L. (Asteraceae) is a cosmopolitan species native to Europe commonly known as lettuce, sowthistle, chicory, or fake dandelion, considered a weed. However, for many years in various cultures around the world, it has been used as food and medicinal plant. The aim of this integrative review is to document the ethnomedical, phytochemical, and pharmacological information of this species. Forty-one papers document the use of S. oleraceus to heal of a wide variety of diseases. However, gastrointestinal problems, diabetes, inflammation, infections, hepatitis, wounds, and to consume it as food are the most common uses. On the other hand, only 11 items highlight that the main groups of secondary metabolites in this species are flavonoids and terpene lactones. Finally, 45 items reveal that antioxidant, antimicrobial, antiproliferative and cytotoxic were the most studied pharmacological activities. In vitro and in vivo studies of extracts and components isolated from different parts of S. oleraceus have provided a concrete overview of the pharmacological properties of this species that supports its ethnomedical uses in cultures from different parts of the world. The reports of this species have focused solely on the study of the complete plant, leaves, and aerial parts, so it is necessary to study other parts of this species to search for bioactive compounds. No clinical studies were found, which creates an opportunity to expand scientific knowledge of this species.

Kisspeptins and reproduction: physiological roles and regulatory mechanisms.

Procreation is essential for survival of species. Not surprisingly, complex neuronal networks have evolved to mediate the diverse internal and external environmental inputs that regulate reproduction in vertebrates. Ultimately, these regulatory factors impinge, directly or indirectly, on a final common pathway, the neurons producing the gonadotropin-releasing hormone (GnRH), which stimulates pituitary gonadotropin secretion and thereby gonadal function. Compelling evidence, accumulated in the last few years, has revealed that kisspeptins, a family of neuropeptides encoded by the Kiss1 gene and produced mainly by neuronal clusters at discrete hypothalamic nuclei, are pivotal upstream regulators of GnRH neurons. As such, kisspeptins have emerged as important gatekeepers of key aspects of reproductive maturation and function, from sexual differentiation of the brain and puberty onset to adult regulation of gonadotropin secretion and the metabolic control of fertility. This review aims to provide a comprehensive account of the state-of-the-art in the field of kisspeptin physiology by covering in-depth the consensus knowledge on the major molecular features, biological effects, and mechanisms of action of kisspeptins in mammals and, to a lesser extent, in nonmammalian vertebrates. This review will also address unsolved and contentious issues to set the scene for future research challenges in the area. By doing so, we aim to endow the reader with a critical and updated view of the physiological roles and potential translational relevance of kisspeptins in the integral control of reproductive function.

Early metabolic programming of puberty onset: impact of changes in postnatal feeding and rearing conditions on the timing of puberty and development of the hypothalamic kisspeptin system.

Kiss1 neurons have recently emerged as a putative conduit for the metabolic gating of reproduction, with leptin being a regulator of hypothalamic Kiss1 expression. Early perturbations of the nutritional status are known to predispose to different metabolic disorders later in life and to alter the timing of puberty; however, the potential underlying mechanisms remain poorly defined. Here we report how changes in the pattern of postnatal feeding affect the onset of puberty and evaluate key hormonal and neuropeptide [Kiss1/kisspeptin (Kp)] alterations linked to these early nutritional manipulations. Female rats were raised in litters of different sizes: small (four pups per dam: overfeeding), normal (12 pups per dam), and large litters (20 pups per litter: underfeeding). Postnatal overfeeding resulted in persistently increased body weight and earlier age of vaginal opening, as an external sign of puberty, together with higher levels of leptin and hypothalamic Kiss1 mRNA. Conversely, postnatal underfeeding caused a persistent reduction in body weight, lower ovarian and uterus weights, and delayed vaginal opening, changes that were paralleled by a decrease in leptin and Kiss1 mRNA levels. Kisspeptin-52 immunoreactivity (Kp-IR) in the hypothalamus displayed similar patterns, with lower numbers of Kp-IR neurons in the arcuate nucleus of postnatally underfed animals, and a trend for increased Kp-positive fibers in the periventricular area of early overfed rats. Yet, gonadotropin responses to Kp at puberty were similar in all groups, except for enhanced responsiveness to low doses of Kp-10 in postnatally underfed rats. In conclusion, our data document that the timing of puberty is sensitive to both overfeeding and subnutrition during early (postnatal) periods and suggest that alterations in hypothalamic expression of Kiss1/kisspeptin may underlie at least part of such programming phenomenon.

The anorexigenic neuropeptide, nesfatin-1, is indispensable for normal puberty onset in the female rat.

The hypothalamic peptide, nesfatin-1, derived from the precursor NEFA/nucleobindin 2 (NUCB2), was recently identified as anorexigenic signal, acting in a leptin-independent manner. Yet its participation in the regulation of other biological functions gated by body energy status remains unexplored. We show herein that NUCB2/nesfatin-1 is involved in the control of female puberty. NUCB2/nesfatin mRNA and protein were detected at the hypothalamus of pubertal female rats, with prominent signals at lateral hypothalamus (LHA), paraventricular (PVN), and supraoptic (SON) nuclei. Hypothalamic NUCB2 expression raised along pubertal transition, with detectable elevations of its mRNA levels at LHA, PVN, and SON, and threefold increase of its total protein content between late-infantile and peripubertal periods. Conditions of negative energy balance, such as 48 h fasting or sustained subnutrition, decreased hypothalamic NUCB2 mRNA and/or protein levels in pubertal females. At this age, central administration of nesfatin-1 induced modest but significant elevations of circulating gonadotropins, whose magnitude was notably augmented in conditions of food deprivation. Continuous intracerebroventricular infusion of antisense morpholino oligonucleotides (as-MONs) against NUCB2 along pubertal maturation, which markedly reduced hypothalamic NUCB2 protein content, delayed vaginal opening and decreased ovarian weights and serum luteinizing hormone (LH) levels. In contrast, in adult female rats, intracerebroventricular injection of nesfatin did not stimulate LH or follicle-stimulating hormone secretion; neither did central as-MON infusion alter preovulatory gonadotropin surges, despite suppression of hypothalamic NUCB2. In sum, our data are the first to disclose the indispensable role of NUCB2/nesfatin-1 in the central networks driving puberty onset, a function that may contribute to its functional coupling to energy homeostasis.

Novel role of the anorexigenic peptide neuromedin U in the control of LH secretion and its regulation by gonadal hormones and photoperiod.

Neuromedin U (NMU) is a widely spread neuropeptide, with predominant expression at the gastrointestinal tract and brain, putatively involved in the regulation of a diversity of biological functions, including food intake, energy balance and circadian rhythms; all closely related to reproduction. Yet, the implication of NMU in the control of the gonadotropic axis remains scarcely studied. We report herein analyses on the hypothalamic expression and function of NMU in different physiological and experimental states of the rat reproductive system. Expression of NMU mRNA at the hypothalamus was persistently detected along female postnatal development, with maximum levels in adulthood that fluctuated across the cycle and were modulated by ovarian steroids. Acute central administration of NMU evoked increases of serum LH levels in pubertal female rats, while repeated injection of NMU tended to advance vaginal opening. Likewise, central injection of NMU increased serum LH concentrations in cycling female rats, with peak responses in estrus. In contrast, NMU significantly inhibited preelevated LH secretion in gonadectomized and kisspeptin-treated rats. Finally, in noncycling females due to photoperiodic manipulation (constant light), hypothalamic NMU mRNA levels were markedly depressed, but relative LH responses to exogenous NMU were significantly augmented. All together, our present data support a predominant stimulatory role of NMU in the control of the female gonadotropic axis, which appears under the influence of developmental, hormonal, and photoperiodic cues, and might contribute to the joint regulation of energy balance, biological rhythms, and reproduction.

Expression of hypothalamic KiSS-1 system and rescue of defective gonadotropic responses by kisspeptin in streptozotocin-induced diabetic male rats.

Hypogonadotropism is a common feature of uncontrolled diabetes, for which the ultimate mechanism remains to be elucidated. Kisspeptins, ligands of G protein-coupled receptor 54 (GPR54) encoded by the KiSS-1 gene, have recently emerged as major gatekeepers of the gonadotropic axis. Alteration in the hypothalamic KiSS-1 system has been reported in adverse metabolic conditions linked to suppressed gonadotropins, such as undernutrition. However, its potential contribution to defective gonadotropin secretion in diabetes has not been evaluated. We report herein analyses of luteinizing hormone (LH) responses to kisspeptin and hypothalamic expression of the KiSS-1 gene in streptozotocin (STZ)-induced diabetic male rats. In addition, functional studies involving kisspeptin replacement or continuous administration of leptin and insulin to diabetic male rats are presented. Kisspeptin administration evoked robust LH and testosterone bursts and enhanced postgonadectomy LH concentrations, despite prevailing attenuation of gonadotropic axis in diabetic animals. In addition, hypothalamic KiSS-1 mRNA levels were unambiguously decreased in diabetic male rats, and the postorchidectomy rise in KiSS-1 mRNA was severely blunted. Repeated administration of kisspeptin to diabetic rats evoked persistent LH and testosterone responses and partially rescued prostate and testis weights. In addition, central infusion of leptin, but not insulin, was sufficient to normalize hypothalamic KiSS-1 mRNA levels, as well as LH and testosterone concentrations. In summary, we provide evidence for altered expression of the hypothalamic KiSS-1 system in a model of uncontrolled diabetes. This observation, together with the ability of exogenous kisspeptin to rescue defective LH responses in diabetic rats, unravel the physiopathological implication, and potential therapeutic intervention, of the KiSS-1 system in altered gonadotropin secretion of type 1 diabetes.

A phase II trial of gemcitabine and weekly high-dose 5-fluorouracil in a 48-hour continuous-infusion schedule in patients with advanced pancreatic carcinoma. A study of the Spanish Cooperative Group for Gastrointestinal Tumour Therapy (TTD).

AIM: A multi-centred, open-labelled, phase 11 study containing 46 patients was conducted to evaluate the clinical benefit of gemcitabine (1,400 mg/m(2)) combined with 5-FU (3 g/m(2)) in a 48 h continuous infusion (CI). METHODS: Both drugs were administered on days 1, 8 and 15 of every 4 week cycle in chemotherapy-naïve patients with locally advanced unresectable metastatic pancreatic carcinoma. The minimum follow-up was 6 months. RESULTS: Clinical benefit response was the primary endpoint and this was achieved by 24.4% of the patients. Quality of life (QoL) improved in 16.6% of patients. Objective response was observed in 7% of the patients. The median progression-free survival (PFS) was 14.4 weeks and the median overall survival (OS) time was 22.7 weeks. One-year survival was 25%. The most frequent grade 3-4 toxicities were neutropenia (45%), mucositis (7.5%) and hyperbilirubinaemia (10.5%). CONCLUSIONS: This schedule was not superior in terms of clinical benefit, response rate, PFS and OS than standard gemcitabine treatment

A phase II trial of gemcitabine and weekly high-dose 5-fluorouracil in a 48-hour continuous-infusion schedule in patients with advanced pancreatic carcinoma. A study of the Spanish Cooperative Group for Gastrointestinal Tumour Therapy (TTD)

Aim. A multi-centred, open-labelled, phase II study containing 46 patients was conducted to evaluate the clinical benefit of gemcitabine (1,400 mg/m2) combined with 5-FU (3 g/m2) in a 48h continuous infusion (CI). Methods. Both drugs were administered on days 1, 8 and 15 of every 4 week cycle in chemotherapy-naïve patients with locally advanced un-resectable metastatic pancreatic carcinoma. The minimum follow-up was 6 months. Results. Clinical benefit response was the primary endpoint and this was achieved by 24.4% of the patients. Quality of life (QoL) improved in 16.6% of patients. Objective response was observed in 7% of the patients. The median progression-free survival (PFS) was 14.4 weeks and the median overall survival (OS) time was 22.7 weeks. One-year survival was 25%. The most frequent grade 3-4 toxicities were neutropenia (45%), mucositis (7.5%) and hyperbilirubinaemia (10.5%). Conclusions. This schedule was not superior in terms of clinical benefit, response rate, PFS and OS than standard gemcitabine treatment

Effects of ghrelin upon gonadotropin-releasing hormone and gonadotropin secretion in adult female rats: in vivo and in vitro studies.

A reproductive facet of ghrelin, a stomach-derived orexigenic peptide involved in energy homeostasis, has been recently suggested, and predominantly inhibitory effects of ghrelin upon luteinizing hormone (LH) secretion have been demonstrated in rat models. Yet, the modulatory actions of ghrelin on the gonadotropic axis remain scarcely evaluated. We report herein a detailed analysis of the effects of ghrelin upon LH and follicle-stimulating hormone (FSH) secretion in the female rat, using a combination of in vivo and in vitro approaches. Intracerebroventricular administration of ghrelin (3 nmol/rat) evoked a significant inhibition of LH secretion in cyclic female rats throughout the estrous cycle (proestrus afternoon, estrus, metestrus), as well as in ovariectomized females. In good agreement, gonadotropin-releasing hormone (GnRH) secretion by hypothalamic fragments from ovariectomized females was significantly inhibited by ghrelin. In contrast, ghrelin dose-dependently stimulated basal LH and FSH secretion by pituitary tissue in vitro; a phenomenon that was proven dependent on the phase of estrous cycle, as it was neither detected at estrus nor observed after ovariectomy. Conversely, GnRH-stimulated LH secretion in vitro was persistently inhibited by ghrelin regardless of the stage of the cycle, whereas stimulated FSH secretion was only inhibited by ghrelin at estrus. In addition, cyclic fluctuations in mRNA levels of growth hormone secretagogue receptor (GHS-R)1a, i.e. the functional ghrelin receptor, were observed in the pituitary, with low values at estrus and metestrus. GHS-R1a mRNA levels, however, remained unchanged after ovariectomy. In summary, our data illustrate a complex mode of action of ghrelin upon the gonadotropic axis, with predominant inhibitory effects at central (hypothalamic) levels and upon GnRH-induced gonadotropin secretion, but direct stimulatory actions on basal LH and FSH secretion. Overall, our results further document the reproductive role of ghrelin, which might be relevant for the integrated control of energy balance and reproduction.

Ghrelin inhibits prolactin secretion in prepubertal rats.

Ghrelin, a novel 28-amino-acid peptide primarily expressed in stomach and hypothalamus, has recently emerged as the endogenous ligand for the GH-secretagogue receptor with ability to stimulate GH secretion in humans and rats. In addition, ghrelin also stimulates prolactin (PRL) secretion in humans. However, its role in the regulation of PRL secretion in rats remains largely unknown. In this context, the present experiments were carried out to analyze the effects of ghrelin on PRL secretion in male and female rats. In detail, the ontogeny and potential sexual dimorphism in the PRL response to ghrelin was evaluated. In addition, the hypothalamic and/or pituitary site of primary action of ghrelin, as well as the possible interactions between ghrelin and other neurotransmitters, as nitric oxide, dopamine, serotonin or excitatory amino acids, in the precise control of PRL secretion were assessed. Experiments were conducted in prepubertal male and female animals. Systemic (i.p.) and central (i.c.v.) administration of ghrelin significantly inhibited PRL secretion. Such an inhibitory effect became evident after day 10 of age, was similar in males and females, and was also observed in hyperprolactinemic aged female rats. In contrast, however, challenge of pituitary samples in vitro with increasing doses of ghrelin (10(-9)-10(-7)M) failed to inhibit PRL secretion. Analysis of interactions between ghrelin and other systems involved in the control of PRL secretion revealed that neither blockade of dopaminergic receptors with domperidone, nor enhancement of serotoninergic tone with fluoxetine + 5-hydroxytryptophan altered the inhibitory response to ghrelin in terms of PRL secretion. Similarly, blockade of nitric oxide synthases with L-nitro-arginine-methyl ester failed to modify the magnitude of ghrelin-induced inhibition of PRL secretion, whereas ghrelin was unable to further decrease serum PRL levels after activation of ionotropic excitatory amino acid receptors by administration of NMDA or AMPA. In conclusion, our data indicate that ghrelin is able to inhibit PRL secretion in male and female rats, likely through an extrapituitary primary site of action that is independent of nitric oxide, dopamine, and serotonin systems.

Role of ghrelin in the control of growth hormone secretion in prepubertal rats: interactions with excitatory amino acids.

Ghrelin is a 28-amino-acid peptide, with an essential n-octanoyl modification at Ser3, that elicits growth-hormone (GH) secretion in rats and humans. At present, the mechanisms of ghrelin action and its interactions with other systems controlling GH secretion remain poorly characterized. In this context, the present study was undertaken to obtain information about ontogeny and possible gender differences in the GH-releasing activity of ghrelin, and to delineate its primary site(s) of action at the hypothalamus and/or pituitary. In addition, the interactions between ghrelin and other relevant signals in the control of GH secretion, such as excitatory amino acids (EAAs), nitric oxide (NO) and serotonin, were assessed. Experiments were carried out in infantile-prepubertal animals, when GH pulsatility is not yet established. Systemic administration of ghrelin (25 nmol/rat, i.p.) to 5-, 10- and 23-day-old male and female rats increased plasma GH levels from day 10 onwards. This action was NO dependent, since it disappeared in 23-day-old males after pretreatment with an inhibitor of NO synthase (NAME). Similarly, central infusion of ghrelin (3 nmol/rat, i.c.v.) elicited GH responses in 10- and 23-day-old animals significantly higher than after systemic administration. By contrast, in vitro challenge of pituitary tissue with increasing doses of ghrelin (10(-9)-10(-7) M) failed to enhance GH release into the incubation medium, whereas stimulation with GH-releasing hormone (GHRH; 10(-7) M) or GHRP-6 (10(-7) M) was effective. Finally, effects of ghrelin were blocked by pretreatment with MK-801 and NBQX antagonists of EAA ionotropic receptors and after manipulation of endogenous serotoninergic tone. In addition, the potent releasing activity of EAA agonists NMDA and AMPA was blunted by pretreatment with D-Lys3-GHRP-6, a selective antagonist of the cognate ghrelin receptor, i.e. the GH-secretagogue receptor. In conclusion, our results demonstrate that GH-releasing activity of ghrelin appears early in the infantile period, is NO dependent and involves a primary hypothalamic site of action. The data also demonstrate for the first time the existence of a cross-talk between ghrelin and other neurotransmitter systems, such as EAAs and serotonin, in precise control of GH secretion.