Oestrogen-dependent stimulation of luteinising hormone release by galanin-like peptide in female rats

Study of failures in a rabbit line selected for growth rate

<p>Selection for growth rate is negatively related with reproductive fitness. The aim of this work was to analyse the causes of fertility failure in rabbit does selected for growth rate and characterised for reproductive deficiencies (line R). In the experiment, 82 does were divided into 2 groups: naturally mated (NM) and artificially inseminated (AI), to relate luteinizing hormone (LH) concentration with ovulation induction and pregnancy rate by laparoscopic determination. Additionally, in 38 of these females ovulation rate and metabolites determination (leptin, NEFA, BOHB and glucose) were analysed and perirenal fat thickness measurement and live body weight (LBW) determined. The results showed that all ovulated does (both NM and AI) presented higher concentrations of LH than non-ovulated females. In addition, non-ovulated females showed high levels of leptin and BOHB, as well as LBW. Females from line R have an inherit reduced fertility due to ovulation failure as a consequence of a reduction in LH release, which could be explained by a heavier body weight and higher leptin concentrations.</p>

The regulative effect of galanin family members on link of energy metabolism and reproduction

It is essential for the species survival that an efficient coordination between energy storage and reproduction through endocrine regulation. The neuropeptide galanin, one of the endocrine hormones, can potently coordinate energy metabolism and the activities of hypothalamic-pituitary-gonadal reproductive axis to adjust synthesis and release of metabolic and reproductive hormones in animals and humans. However, few papers have summarized the regulative effect of the galanin family members on the link of energy storage and reproduction as yet. To address this issue, this review attempts to summarize the current information available about the regulative effect of galanin, galanin-like peptide and alarin on the metabolic and reproductive events, with special emphasis on the interactions between galanin and hypothalamic gonadotropin-releasing hormone, pituitary luteinizing hormone and ovarian hormones. This research line will further deepen our understanding of the physiological roles of the galanin family in regulating the link of energy metabolism and reproduction.

Plasma galanin is a biomarker for severity of major depressive disorder

OBJECTIVE

This study investigated the association between plasma galanin level and depression severity.

METHODS

The severity of depression symptoms of 79 patients with major depressive disorder (MDD; 52 women and 27 men, 71 patients in onset, 8 in remission) was assessed using the 17-item Hamilton Depression Rating Scale. Venous fasting blood samples (5 mL) were taken from the 79 MDD patients, 35 healthy siblings, and 19 healthy controls, and plasma samples were prepared. Galanin levels in the plasma were measured by radioimmunoassay.

RESULTS

Plasma galanin in MDD patients was significantly higher than that of remission patients, healthy siblings, or healthy controls (P < 0.05) There was no significant difference between the healthy sibling and healthy control groups (P = 0.924). Plasma galanin of remission patients was also significantly higher than that of healthy controls (P < 0.05). There was no significant correlation between age and galanin levels in the 79 patients (r = 0.053, P = 0.646), nor was there a correlation between age and galanin levels when patients were stratified by gender (P > 0.05). There was a significant positive correlation between plasma galanin levels and depression severity in women MDD patients (r = 0.329, df = 42, P = 0.020), but not in men patients.

CONCLUSIONS

Plasma galanin levels may be an important biomarker for depression severity, especially in female patients.

When do we eat? Ingestive behavior, survival, and reproductive success

The neuroendocrinology of ingestive behavior is a topic central to human health, particularly in light of the prevalence of obesity, eating disorders, and diabetes. The study of food intake in laboratory rats and mice has yielded some useful hypotheses, but there are still many gaps in our knowledge. Ingestive behavior is more complex than the consummatory act of eating, and decisions about when and how much to eat usually take place in the context of potential mating partners, competitors, predators, and environmental fluctuations that are not present in the laboratory. We emphasize appetitive behaviors, actions that bring animals in contact with a goal object, precede consummatory behaviors, and provide a window into motivation. Appetitive ingestive behaviors are under the control of neural circuits and neuropeptide systems that control appetitive sex behaviors and differ from those that control consummatory ingestive behaviors. Decreases in the availability of oxidizable metabolic fuels enhance the stimulatory effects of peripheral hormones on appetitive ingestive behavior and the inhibitory effects on appetitive sex behavior, putting a new twist on the notion of leptin, insulin, and ghrelin "resistance." The ratio of hormone concentrations to the availability of oxidizable metabolic fuels may generate a critical signal that schedules conflicting behaviors, e.g., mate searching vs. foraging, food hoarding vs. courtship, and fat accumulation vs. parental care. In species representing every vertebrate taxa and even in some invertebrates, many putative "satiety" or "hunger" hormones function to schedule ingestive behavior in order to optimize reproductive success in environments where energy availability fluctuates.

High fat diet affects reproductive functions in female diet-induced obese and dietary resistant rats

The incidence of ovulatory disorders is common in obese animal models. The mechanism behind this effect is unclear. We hypothesised that a high-fat (HF) diet induces alterations in neuroendocrine mechanisms resulting in anovulation in diet-induced obese (DIO) animals. Adult female DIO and diet-resistant (DR) rats were fed either chow or a HF diet (45% calories from fat) for 6 weeks. Oestrous cyclicity and body weight were monitored regularly. At the end of treatment, rats were implanted with a jugular catheter to monitor luteinising hormone (LH) levels on the day of pro-oestrous. Rats were sacrificed on the next pro-oestrous, and their brains and ovaries were collected. Plasma from trunk blood was analysed for oestradiol and leptin concentrations. Ovaries were fixed and sectioned for histological analysis. Brains were removed, frozen and sectioned, and norepinephrine (NE) concentrations in discrete hypothalamic areas were measured using high-performance liquid chromatography with electrochemical detection. A HF diet exposure affected oestrous cyclicity in both DIO and DR rats, with the effect being more pronounced in DIO animals. HF diet exposure increased leptin levels in both DIO and DR rats. Oestradiol levels were low in the DIO-HF group. NE levels in the hypothalamus were unaffected by HF diet or genotype. A normal LH surge was observed in DR-Chow rats and LH levels were low in the remaining groups. These results lead to the conclusion that DIO rats have an inherently reduced reproductive capacity and exposure to a HF diet decreases it further. A reduction in oestradiol and LH surge levels could contribute to this effect; however, the underlying mechanisms need to be investigated further.

Alarin stimulates food intake in male rats and LH secretion in castrated male rats

Alarin is a newly identified member of the galanin family of neuropeptides that includes galanin-like peptide (GALP) and galanin. Alarin was discovered as an alternate transcript of the GALP gene in neuroblastoma cells, and subsequently alarin mRNA was detected in the brain of rodents. GALP and galanin are important central regulators of both feeding and reproductive behavior. We hypothesized, that, as a member of the galanin family of peptides, alarin would also have central effects on feeding and reproduction. To test this hypothesis, we treated male rats with alarin intracerebroventricularly (i.c.v.) and measured its effects on food intake and energy homeostasis as well as sexual behavior and luteinizing hormone (LH) secretion. We observed that i.c.v. injection of 1.0 nmol alarin significantly increased food intake (p<0.01) and body weight (p<0.05). Alarin did not affect sexual behavior in male rats; however, alarin did significantly (p<0.01) increase LH levels in castrated, but not intact, male rats. Alarin immunoreactive cell bodies were detected within the locus coeruleus and locus subcoeruleus of the midbrain, which is a brainstem nucleus involved in coordinating many physiological activities, including food intake and reproduction. Lastly, alarin stimulated Fos induction in hypothalamic nuclei, such as the paraventricular nucleus and the nucleus of the tractus solitarious. Our studies demonstrate that alarin, like other members of the galanin family, is a neuromediator of food intake and body weight.

Is the role of estrogens and estrogen receptors in epilepsy still underestimated?

The etiology of epilepsy still represents an open subject of discussions and research. Contrary to the majority of diseases for which drugs are developed following the origin of disease, epilepsy is treated symptomatically because it is perceived to have diverse causes. Recent results of oncological, neurological, developmental and biochemical studies suggest that the reproductive dysfunction in men and women, as a side effect related with antiepileptic therapy, points to the single origin of this disease. It seems that contrary to the present definition of estrogen as a compound affecting seizure susceptibility, based on causal chains: of increased estrogen levels (alcohol intake) and seizure, fact that all antiepileptic drugs are aromatase inhibitors or have estrogen binding properties, described cases of seizures in epileptic patients taking quinine as preventive therapy against malaria, impact of photic activation and sleep on estrogen level, it can be assumed that estrogen plays the leading role in the mutual origin of different types of epilepsy.