In the Pursuit of Metabolic Markers of Systemic Sclerosis-Plasma Adiponectin and Omentin-1 in Monitoring the Course of the Disease.

Systemic sclerosis (SSc) is a connective tissue disease leading to cutaneous and visceral fibrosis. Pathological features of SSc include immune dysregulation, vasculopathy, and impaired angiogenesis. Adipokines act as cytokines and hormones and are involved in various pathological processes, including metabolic disorders, inflammation, vasculopathy, and fibrosis. This study aimed to determine the level of omentin-1 and adiponectin to evaluate their potential role in the pathogenesis of SSc. We assessed serum omentin-1 and adiponectin as well as metabolic parameters in 58 patients with SSc and 30 healthy controls. The follow-up was performed in SSc individuals. Omentin-1 levels were significantly higher in SSc individuals as compared to the controls. In post-hoc analysis, omentin-1 was higher in the group with disease duration ≥7 years than in the control group. A positive correlation was noted between disease duration and both adipokines and increased with longer disease duration. However, there were no correlations between selected adipokines and metabolic parameters. Enhanced omentin-1 levels and higher levels of omentin-1 in patients with longer disease duration may suggest that omentin-1 is involved in the pathomechanisms of SSc as its concentrations are not directly related to BMI, age, and insulin resistance.

Obesity as a Risk Factor for Breast Cancer-The Role of miRNA.

Breast cancer (BC) is the most common cancer diagnosed among women in the world, with an ever-increasing incidence rate. Due to the dynamic increase in the occurrence of risk factors, including obesity and related metabolic disorders, the search for new regulatory mechanisms is necessary. This will help a complete understanding of the pathogenesis of breast cancer. The review presents the mechanisms of obesity as a factor that increases the risk of developing breast cancer and that even initiates the cancer process in the female population. The mechanisms presented in the paper relate to the inflammatory process resulting from current or progressive obesity leading to cell metabolism disorders and disturbed hormonal metabolism. All these processes are widely regulated by the action of microRNAs (miRNAs), which may constitute potential biomarkers influencing the pathogenesis of breast cancer and may be a promising target of anti-cancer therapies.

Inflammasome NLRP3 Potentially Links Obesity-Associated Low-Grade Systemic Inflammation and Insulin Resistance with Alzheimer's Disease.

Alzheimer's disease (AD) is the most common form of neurodegenerative dementia. Metabolic disorders including obesity and type 2 diabetes mellitus (T2DM) may stimulate amyloid ß (Aß) aggregate formation. AD, obesity, and T2DM share similar features such as chronic inflammation, increased oxidative stress, insulin resistance, and impaired energy metabolism. Adiposity is associated with the pro-inflammatory phenotype. Adiposity-related inflammatory factors lead to the formation of inflammasome complexes, which are responsible for the activation, maturation, and release of the pro-inflammatory cytokines including interleukin-1ß (IL-1ß) and interleukin-18 (IL-18). Activation of the inflammasome complex, particularly NLRP3, has a crucial role in obesity-induced inflammation, insulin resistance, and T2DM. The abnormal activation of the NLRP3 signaling pathway influences neuroinflammatory processes. NLRP3/IL-1ß signaling could underlie the association between adiposity and cognitive impairment in humans. The review includes a broadened approach to the role of obesity-related diseases (obesity, low-grade chronic inflammation, type 2 diabetes, insulin resistance, and enhanced NLRP3 activity) in AD. Moreover, we also discuss the mechanisms by which the NLRP3 activation potentially links inflammation, peripheral and central insulin resistance, and metabolic changes with AD.

The role of leptin in selected skin diseases.

Leptin is an adipokine, adipocyte-derived compound, which acts both as a hormone and cytokine. It is mainly synthesized by adipocytes of white adipose tissue. Leptin possesses pleiotropic functions including, among others, stimulation of angiogenesis and production of proinflammatory cytokines. The various types of leptin activity are related to the wide distribution of leptin receptors. This adipokine acts by activating intracellular signaling cascades such as JAKs (Janus kinases), STATs (signal transducers and activators of transcription), and others.In a course of obesity, an increased serum level of leptin coexists with tissue receptor resistance. It has been reported that enhanced leptin levels, leptin receptor impairment, and dysfunction of leptin signaling can influence skin and hair. The previous studies revealed the role of leptin in wound healing, hair cycle, and pathogenesis of skin diseases like psoriasis, lupus erythematosus, and skin cancers. However, the exact mechanism of leptin's impact on the skin is still under investigation. Herein, we present the current knowledge concerning the role of leptin in psoriasis and selected skin diseases.

Bridging the Gap between Alzheimer's Disease and Alzheimer's-like Diseases in Animals.

The average life span steadily grows in humans and in animals kept as pets or left in sanctuaries making the issue of elderly-associated cognitive impairment a hot-spot for scientists. Alzheimer's disease (AD) is the most prevalent cause of progressive mental deterioration in aging humans, and there is a growing body of evidence that similar disorders (Alzheimer's-like diseases, ALD) are observed in animals, more than ever found in senescent individuals. This review reveals up to date knowledge in pathogenesis, hallmarks, diagnostic approaches and modalities in AD faced up with ALD related to different animal species. If found at necropsy, there are striking similarities between senile plaques (SP) and neurofibrillary tangles (NFT) in human and animal brains. Also, the set of clinical symptoms in ALD resembles that observed in AD. At molecular and microscopic levels, the human and animal brain histopathology in AD and ALD shows a great resemblance. AD is fatal, and the etiology is still unknown, although the myriad of efforts and techniques were employed in order to decipher the molecular mechanisms of disease onset and its progression. Nowadays, according to an increasing number of cases reported in animals, apparently, biochemistry of AD and ALD has a lot in common. Described observations point to the importance of extensive in vivo models and extensive pre-clinical studies on aging animals as a suitable model for AD disease.

Insulin and brain aging.

The world's population is living much longer than in the past. It is crucial to find as many pathological factors that deteriorate the health condition and well-being of elderly people as possible. Loss of activity and functions over time is typical for elderly people. Aging affects brain function, metabolism and structure in different ways, and these effects have multiple etiologies. Cognitive impairment, impaired neurotransmitter activity and reduction of brain volume are observed in the elderly population. The process of brain aging is associated with a decrease of central insulin concentration as well as impairment of insulin receptor binding ability, resulting in deterioration of glucose homeostasis in the brain. Peripheral insulin resistance is a typical feature of older age. Data from the literature suggest that high circulating insulin and insulin resistance are important contributors to progressive cognitive impairment and neurodegenerative processes. The maintenance of insulin sensitivity and proper insulin signaling may lead to preserved cognition that results in well-being of elderly people.

Decreased endothelin-1 plasma levels in multiple sclerosis patients: a possible factor of vascular dysregulation?

BACKGROUND: Multiple sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system with possible involvement of vascular dysregulation secondary to endothelial dysfunction caused by destruction of the vessel wall. Vascular dysregulation leads to excessive vasoconstriction or insufficient vasodilatation, resulting in vasospasm mediated by endothelin-1 (ET-1), the most potent and long-lasting mediator. Vascular dysregulation can play an important role in the pathogenesis of some eye disorders and it has been hypothesized that it is a vascular risk factor for glaucomatous optic neuropathy. The aim of this study was to estimate endothelin-1 (ET-1) plasma levels in patients with MS. MATERIAL AND METHODS: The MS group consisted of 39 patients (9 males, 30 females), mean age: 38.8 ± 10.02 years, range: 22-62. The control group consisted of 27 healthy volunteers (3 males and 24 females), mean age: 37.4 ± 10.88 years, range: 20-62; clinically, in a non-active stage of the disease. ET-1 plasma levels were measured using the Endothelin-1 ELISA Kit (Immuno-Biological Laboratories Co., Japan). Statistical analysis was performed with the nonparametric Mann-Whitney U test for independent groups. RESULTS: Endothelin-1 (ET-1) plasma levels were significantly lower in MS patients compared to healthy controls: mean value 0.55 ± 0.44 pg/ml (146.05 ± 118.27 fmol/ml) vs. 0.95 ± 0.48 pg/ml (252.83 ± 127.16 fmol/ml); P=0.012. CONCLUSIONS: Significantly decreased ET-1 plasma levels in the MS patients could reflect the non-active disease at the time of ET-1 measurements or the effects of immunomodulatory treatment, but it cannot be excluded that decreased ET-1 plasma levels in these patients might result from vascular dysregulation.

Assessment of plasma brain-derived neurotrophic factor (BDNF), activity-dependent neurotrophin protein (ADNP) and vasoactive intestinal peptide (VIP) concentrations in treatment-naïve humans with multiple sclerosis.

OBJECTIVE: Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS) characterized by coexisting processes of inflammation, demyelination, axonal neurodegeneration and gliosis. Autoimmune processes play a pivotal role in the disease. The immune system may be modulated by neurotrophins and neurotrophin factors. Aim of the study was to assess plasma levels of brain-derived neurotrophic factor (BDNF), activity-dependent neurotrophin protein (ADNP) and vasoactive intestinal peptide (VIP) in treatment-naïve humans with newly diagnosed multiple sclerosis. We also elucidated the potential influence of selected inflammatory agents on peripheral concentration of BDNF and ADNP. MATERIAL AND METHODS: The study population comprised of 31 untreated patients with MS and 36 controls from a single hospital centre. Assessment of BDNF and ADNP was performed with use of ELISA methods. VIP was measured with RIA. Selected cytokine levels (IL 6, IL 10, and TNF α) were evaluated with ELISA tests. Statistical analyses were performed. RESULTS: We failed to find any significant differences between ADNP, BDNF, VIP, CRP levels and concentration of cytokines between individuals with MS and the controls. No correlation was observed between ADNP, BDNF and VIP as the first parameter and CRP, IL 6, IL 10, TNFα levels and the Expanded Disability Status Scale score in MS. CONCLUSIONS: Newly diagnosed, treatment-naïve patients with MS have comparable levels of plasma BDNF, ADNP and VIP to those of healthy controls.

Plasma chemerin levels in patients with multiple sclerosis.

OBJECTIVES: Chemerin, a novel adipokine produced by adipose tissue and liver, is associated with markers of metabolic syndrome, and additionally, acting as chemoattractant for cells of immune system it may regulate immune cell properties. MATERIAL AND METHODS: In order to evaluate plasma chemerin concentration in multiple sclerosis (MS) individuals we investigated 39 MS patients (among them 23 subjects were lean and 16 were overweight or obese) and 42 controls with tension headaches (29 of them were lean and 13 were overweight or obese). All patients had a brain MRI scan with gadolinium contrast as well as an assessment of the presence of oligoclonal bands in cerebrospinal fluid (CSF) and estimation of the CSF IgG index. The neurologic status was evaluated with use of the Expanded Disability Status Scale. Chemerin levels in plasma were measured using ELISA kit. Lipid profile, glucose and insulin levels, CRP and selected cytokine concentrations were also determined. RESULTS: Plasma chemerin concentrations in overweight/obese MS subjects were higher when comparing to lean MS individuals and the controls, both from lean and overweight/obese subgroups. Significant difference was found between the results of overweight/obese MS and lean controls. CONCLUSIONS: An increase of chemerin levels in patients with multiple sclerosis is associated with overweight and obesity.

Nicotinic acid attenuates amyloid ß1-42-induced mitochondrial dysfunction and inhibits the mitochondrial pathway of apoptosis in differentiated SH-SY5Y cells.

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive memory loss and behavioral disorders. The excessive accumulation of amyloid ß (Aß) and the formation of neurofibrillary tangles (NFTs) damage synaptic connections and the death of neurons. However, the underlying mechanisms of pathogenesis of AD remain unclear. Growing evidence indicates that impaired mitochondrial function may play a crucial role in the development of AD. In the current study, we investigated whether nicotinic acid (NA) could protect against amyloid ß1-42-induced cytotoxicity in differentiated SH-SY5Y cells. Our results revealed the neuroprotective effects of NA on the differentiated SH-SY5Y cells treated with Aß1-42. In detail, the 1-h pre-incubation with NA increased cell viability and lowered LDH levels. NA pre-incubation abolished Aß1-42 treatment-associated alterations of mRNA levels of synaptic genes and enhanced the relative ß3 Tubulin fluorescence intensity. NA eliminated the Aß1-42-induced mitochondrial dysfunction by increasing the potential of mitochondrial membranes and maintaining a balance between the fusion and fission of mitochondria. Moreover, Aß1-42 decreased mRNA levels of anti-apoptotic bcl2 and increased mRNA levels of pro-apoptotic: bim, bak, cytochrome c, and caspase 9. At the same time, the NA pre-treatment reduced Aß1-42-dependent apoptotic death of differentiated SH-SY5Y cells. The above data suggest that NA presents a protective activity against Aß1-42-induced cytotoxicity in differentiated SH-SY5Y cells by inhibiting the mitochondrial pathway of apoptosis and restoring the proper function of mitochondria.

Plasma NPY concentrations in women with acute ischemic stroke.

OBJECTIVE: It has been reported that plasma NPY levels were increased in obesity, type 2 diabetes mellitus and hypertension. The symptoms of metabolic syndrome frequently appear in patients with acute ischemic stroke. The association between plasma NPY levels and metabolic markers in women with acute ischemic stroke was investigated in the current study. METHODS: Plasma NPY concentrations were determined using radioimmunoassay in 58 women aged 60-85 (mean age: 76.5±0.8) with acute ischemic stroke and in 24 women aged 63-67 (mean age: 65.6±0.6) of the control group. Stroke was defined according to the NIHSS (National Institute of Health Stroke Scale) and was confirmed using CT or MR scan. RESULTS: The prevalence of type 2 diabetes, hypertension and insulin resistance was higher in the group of patients with stroke. Plasma NPY levels measured during the 1st day and 10 days after the acute phase of stroke were significantly lower (p<0.001) compared to the control group. CONCLUSION: In women with acute ischemic stroke plasma NPY concentrations were decreased in spite of higher frequency of the occurrence of the symptoms of metabolic syndrome.

Do novel adipokines play a causative or only modulating role in the pathogenesis of obesity and metabolic disorders?

Adipose tissue is an endocrine and paracrine organ that releases a large number of bioactive mediators. Approximately 100 adipokines have been identified including cytokines, chemokines, growth factors and enzymes. The use of adipoproteomic analyses resulted in new findings and, in consequence, the number of new adipokines is rising rapidly. Novel adipokines such as visfatin, vaspin and omentin were discovered about five years ago. Visfatin and vaspin production and secretion take place in adipocytes, but omentin comes from the stromal cells of adipose tissue. Several differences are noticeable between these adipokines especially in correlation with obesity as visfatin and vaspin serum levels increase in obese subjects while omentin serum levels decrease. It has been suggested that these adipokines act as insulin-sensitizers/insulin-mimetics. Increasing number of publications reporting the role of new adipokines does not allow to assess clearly the influence of those adipokines on the pathogenesis of obesity.

Resistin levels in women with ischemic stroke.

OBJECTIVES: Resistin may be an independent inflammatory marker of atherosclerosis. Therefore, its circulating level might be important prognostic factor of cardiovascular disease in humans. We aimed in this study to assess plasma resistin concentration in Polish women with acute ischemic stroke, who additionally suffer from chronic diseases: diabetes, hypertension and/or obesity. The changes of resistin levels after 10 days from the onset of stroke and possible associations between resistin and pro-inflammatory cytokine TNFα were also evaluated. MATERIAL AND METHODS: Material consisted of 41 women with ischemic stroke (aged 60-85 years) and 64 controls (aged 60-85 years). Circulating resistin and TNFα concentrations were measured using ELISA. Blood was taken twice in the stroke group, in the first and tenth day from the onset of clinical symptoms, and only once in the controls. Clinical and biochemical data (blood pressure, weight, height, glucose, insulin, lipid profile) were collected. RESULTS: Higher concentrations of resistin and TNFα were observed in ischemic stroke patients at the first day comparing to the controls. Second evaluation after 10 days in comparison with the first measurement revealed significantly higher TNFα levels and non-significant lower values of resistin. Resistin positively correlated with TNFα and stroke severity. CONCLUSIONS: Changes in resistin and TNFα concentrations were observed in the course of stroke. Further investigations are required to assess the implication of these findings. Higher resistin concentration might be associated with worse neurological deficits.

The evaluation of estradiol and leptin action on the activity of the somatotropic and gonadotropic axes in peripubertal female rats.

OBJECTIVE: Available data suggest that estrogens and leptin play a role in the control of the pubertal process. In humans and some mammal species the increase of the activity of gonadotropic axis accompanies the decrease in the rate of growth at puberty. The effect of 17ß-estradiol and/or leptin administration on the somatotropic and gonadotropic axes was studied using prepubertal female rats as an animal model. MATERIAL AND METHODS: Prepubertal female rats received estradiol/saline, estradiol/leptin, oil/leptin or oil/saline (vehicles) respectively. The changes of growth rate, and serum 17ß-estradiol, leptin, GH, IGF-I and gonadotropins levels as well as LHRH and estrogen receptor (ER) concentrations in the medial basal hypothalamus (MBH) and the pituitary were determined. All hormones concentrations were measured by radioimmunoassay and ER by radioligand methods . RESULTS: In estradiol and/or leptin treated animals noticeable reduction of rate of growth was found. The decrease of growth in response to estradiol treatment accompanied the increase GH level and the decrease of IGF-I concentration in the circulation. Both hormones operating together activated reproductive axis, what was manifested by a significant increase of LHRH abundant in the hypothalamus as well as elevated LH and FSH levels in the circulation. In these rats a significant decrease of the estrogen receptor concentrations in the pituitary was observed. CONCLUSION: The role of estradiol and leptin in the control of growth and reproduction seems to overlap only partially. Estradiol plays a significant role in the activation of the reproductive axis, and leptin takes part as a permissive factor in pubertal process.

Evaluation of orexin A activity on LH and FSH release from primary culture pituitary cells in immature and mature female rats.

OBJECTIVES: Orexin A (OxA) is a regulatory neuropeptide which is involved in the control of various autonomic and neuroendocrine functions. It regulates sleep-wake cycle, food intake and modulates the hypothalamic and pituitary hormones secretion. Orexin A acts through two types of receptors, which proved to exist in the pituitary. This may indicate the possibility of direct action of OxA on the adenohypophysis level. The aim of this study was to evaluate the direct effect of orexin A on gonadotropin (LH and FSH) release from cultured pituitary cells of immature female rats as well as mature female rats (ovariectomized and ovariectomized and estradiol treated rats). MATERIAL AND METHODS: The effect of 0.1 nM and 100 nM orexin A on LH and FSH release from anterior pituitary cells after 1 h of incubation was examined in immature female rats (IM) as well as mature female (ovariectomized - M/OVX; and ovariectomized and estradiol treated - M/OVX+E2) rats. The concentration of LH and FSH in medium was determined by RIA method. RESULTS: Orexin A at a dose of 0.1 nM and 100 nM significantly stimulated LH secretion in IM group. In M/OVX group release of LH was inhibited by OxA only in higher dose (100 nM). No effect of orexin A on FSH secretion was found. CONCLUSIONS: OxA may directly modulate LH secretion from cultured pituitary cells and it has the contradictory effect on LH release in immature and ovariectomized mature female rats.

The influence of cocaine-amphetamine regulated transcript (CART) on pituitary hormones, corticosterone and leptin levels in starved rats.

OBJECTIVE: CART is involved in the control of food intake and hormonal secretion. We aimed to evaluate the effects of CART on hormonal profile in starved rats. METHODS: Study group included 100 male rats. Under conditions of food limitation CART (55-102) was given centrally (icv) or peripherally (iv). Non-starved animals underwent identical procedure. Vehicle (aCSF or saline)-injected rats served and as a controls. 60 minutes after CART or vehicle administration blood was collected to assess pituitary hormones (LH, FSH, PRL, GH, ACTH, TSH), corticosterone and leptin concentrations. RESULTS: Itracerebroventricular CART injection resulted in a significant increase in PRL, GH and corticosterone concentrations in non-starved rats compared with vehicle injected animals. However, in a group of starved animals only leptin levels were decreased in comparison with fasted controls. Peripheral CART administration caused a significant increase in PRL, GH and TSH levels in non-starved rats but no changes in investigated hormone levels were observed in starved animals when compared to saline injected controls. CONCLUSIONS: Our results indicate that CART is able to modulate hormonal profile in a non-starved rats. However, the modulatory effect depends on the CART administration method. Interestingly, CART administration, both icv and iv, does not have an impact on pituitary hormones and corticosterone levels in a course of food limitation.

Decreased total serum adiponectin and its isoforms in women with acute ischemic stroke.

OBJECTIVE: An association between cerebral infarct risk factors and serum adiponectin levels (both total and separate isoforms) has previously been identified. The aim of this study was to assess circulating levels of all forms of adiponectin in the course of an ischemic stroke. MATERIAL AND METHODS: Adiponectin and its isoforms (HMW, MMW and LMW) were measured in serum samples taken from 38 women in the first 24 hours of cerebral infarct and 38 controls matched for gender, body mass index (BMI) and age. In addition, biochemical parameters (glucose, insulin, lipid profile) and clinical data (blood pressure, weight, and height) were evaluated. RESULTS: A significant reduction in serum levels of adiponectin and all examined fractions of this adipokine was observed in women suffering from acute ischemic stroke, compared with the matched controls. CONCLUSIONS: Differences in the serum adiponectin array between stroke subjects and controls were identified and further studies are required to investigate the clinical implications of this finding.

Contribution of Mitochondrial Dysfunction Combined with NLRP3 Inflammasome Activation in Selected Neurodegenerative Diseases.

Alzheimer's disease and Parkinson's disease are the most common forms of neurodegenerative illnesses. It has been widely accepted that neuroinflammation is the key pathogenic mechanism in neurodegeneration. Both mitochondrial dysfunction and enhanced NLRP3 (nucleotide-binding oligomerization domain (NOD)-like receptor protein 3) inflammasome complex activity have a crucial role in inducing and sustaining neuroinflammation. In addition, mitochondrial-related inflammatory factors could drive the formation of inflammasome complexes, which are responsible for the activation, maturation, and release of pro-inflammatory cytokines, including interleukin-1ß (IL-1ß) and interleukin-18 (IL-18). The present review includes a broadened approach to the role of mitochondrial dysfunction resulting in abnormal NLRP3 activation in selected neurodegenerative diseases. Moreover, we also discuss the potential mitochondria-focused treatments that could influence the NLRP3 complex.

The Beneficial Role of Natural Endocrine Disruptors: Phytoestrogens in Alzheimer's Disease.

Alzheimer's disease (AD) is the most common form of dementia with a growing incidence rate primarily among the elderly. It is a neurodegenerative, progressive disorder leading to significant cognitive loss. Despite numerous pieces of research, no cure for halting the disease has been discovered yet. Phytoestrogens are nonestradiol compounds classified as one of the endocrine-disrupting chemicals (EDCs), meaning that they can potentially disrupt hormonal balance and result in developmental and reproductive abnormalities. Importantly, phytoestrogens are structurally, chemically, and functionally akin to estrogens, which undoubtedly has the potential to be detrimental to the organism. What is intriguing, although classified as EDCs, phytoestrogens seem to have a beneficial influence on Alzheimer's disease symptoms and neuropathologies. They have been observed to act as antioxidants, improve visual-spatial memory, lower amyloid-beta production, and increase the growth, survival, and plasticity of brain cells. This review article is aimed at contributing to the collective understanding of the role of phytoestrogens in the prevention and treatment of Alzheimer's disease. Importantly, it underlines the fact that despite being EDCs, phytoestrogens and their use can be beneficial in the prevention of Alzheimer's disease.

Exogenous orexin-A downregulates luteinizing hormone secretory activity in prepubertal female rats.

INTRODUCTION: Orexin-A is a neuropeptide synthesized in the lateral hypothalamus. Orexin-A immunoreactive fibres overlap distribution with GnRH neurons. In adult rats, orexin A is known to affect LH secretion via GnRH release modulation. Because data concerning the impact of orexin-A on the hypothalamo-pituitary axis activity are limited, we focused on the involvement of orexin-A and receptors of NPY in the modulation of LH release and LH subunit b (Lhb) mRNA expression in prepubertal female rats. MATERIAL AND METHODS: Forty immature female Wistar rats were divided into 4 groups and received 2 intracerebroventricular (icv) microinjections of: 1 - artificial cerebrospinal fluid (CSF) (controls); 2 - CSF followed by orexin A; 3 - selective NPY receptor antagonist (BIBP) followed by CSF; 4 - BIBP followed by orexin A. One hour after the last microinjection, all rats were decapitated. Trunk blood was collected, and serum was stored at -20°C for the LH RIA examination. The adenohypophysis was immediately excised, flash-frozen, and kept at -80°C for RNA extraction. Real-time PCR amplification was carried out, and relative Lhb gene expression was calculated. RESULTS: In comparison to the CSF-treated controls with a mean LH serum concentration of 0.40 ± 0.02 ng/mL, the mean LH serum level was diminished both after orexin-A (0.27 ± 0.01 ng/mL) and after BIBP (0.30 ± 0.02 ng/mL) icv microinjections. In the presence of BIBP, orexin-A more effectively inhibited LH release (0.20 ± 0.01 ng/mL) when compared to the BIBP-treated group. Orexin-A and BIBP exerted a consistent inhibitory effect on Lhb mRNA expression levels in the anterior pituitary gland. In comparison to the CSF-treated controls, orexin-A, and BIBP-treated females responded with, respectively, 35% and 40% reduction of Lhb mRNA expression. Orexin-A and BIBP co-administration evoked a further reduction of Lhb gene transcriptional activity. CONCLUSIONS: Orexin-A exerts a down-regulatory effect on LH synthesis and release in immature female rats. Considering that Y1R-oriented down-regulation of endogenous NPY activity did not reverse the suppressive effect of exogenous orexin-A, it might be suggested that NPY and orexin A systems can operate independently to affect gonadotropin activity in the anterior pituitary of the immature female rats.