Central modifications of allopregnanolone and beta-endorphin following subcutaneous administration of Nestorone

The aim of the present study was to evaluate the potential action of Nestorone (alone or in combination with estradiol valerate) on the level of allopregnanolone and of the opioid beta-endorphin in selected brain areas. Wistar ovariectomized rats were given 0.05 mg/(kg day) of estradiol valerate (E2V) or subcutaneous Nestorone at three dose levels: low dose (10 microg/(kg day)), antiovulatory dose (50 micro/(kg day)) and high dose (250 microg/(kg day)) with and without E2V. E2V therapy reversed the reduction of allopregnanolone and beta-endorphin induced by ovariectomy anywhere was analyzed except for the adrenal gland. Nestorone showed no effect on allopregnanolone concentration in serum or any part of the brain tissue when given alone while it had a synergistic increasing effect in allopregnanolone concentration in some parts of the brain (hippocampus, hypothalamus, anterior pituitary and serum) when given at high dose of 250 microg/(kg day) in combination with E2V. At lower doses it possesses a synergistic effect with E2V only in the hippocampus (at 50 microg/(kg day)) and in the anterior pituitary (at 10 and 50 microg/(kg day)). Nestorone administered alone at any dose led to significant increase in beta-endorphin levels in the hippocampus only while, in the high dose group, there was a significant increase in endorphin levels in anterior pituitary and hypothalamus in addition to hippocampus as compared to ovariectomized control rats. In addition, only the highest dose of Nestorone added to estrogen increased beta-endorphin levels of hippocampus and plasma. Thus the lower doses of Nestorone alone or in combination with estrogen do not seem to exert any great effect on both allopregnanolone and beta-endorphin. It is only the highest dose of Nestorone that increases allopregnanolone and beta-endorphin levels in selected brain areas, which are the hippocampus, the hypothalamus, the anterior pituitary and serum/plasma. This suggests that Nestorone at the antiovulatory dose levels may not alter the positive effects of estrogen treatment on mood and behaviour.

Brain derived neurotrophic factor circulating levels in patients undergoing IVF

PURPOSE

The aim of the study was to measure circulating BDNF levels, a neurotrophin recently identified in the ovary, in parallel with estradiol, to verify if assessing this factor could add any predictive value to the outcome of in vitro fertilization.

METHODS

Blood sampling for BDNF and estradiol was performed in 23 subjects undergoing IVF on day 1 (D1), day 8 (D8), day of HCG administration (DHCG) and day of oocyte retrieval.(DOR).

RESULTS

There was a positive correlation between BDNF and estradiol throughout the stimulation cycle in all subjects. In both pregnant and nonpregnant patients, the values of BDNF grew significantly only between D8 and DHCG and remained constant until DOR. Between-group comparisons showed no statistically significant differences in both BDNF and estradiol values throughout the IVF cycle.

CONCLUSION

Although BDNF plasma concentrations are not seemingly predictive of IVF outcome, this neurotrophin is highly correlated to estradiol levels and seems to be an important factor especially in the periovulatory period.

Influence of endogenous and exogenous sex hormones on plasma brain-derived neurotrophic factor

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is a mediator of neuronal plasticity and influences learning, memory and cognitive behaviour. The aim of this study is to assess plasma BDNF variations according to hormonal status.

METHODS

A total of 60 subjects were included: 20 fertile ovulatory women, 15 amenorrhoeic women and 25 postmenopausal women. Blood samples were collected after overnight fasting. For 5 out of the 20 fertile women, samples were collected every 2 days throughout the whole menstrual cycle. Following basal evaluation, 10 out of 25 postmenopausal women were administered a hormone replacement therapy (HRT) and reevaluated after 6 months of treatment. Plasma BDNF concentrations were measured by enzyme-linked immunosorbent assay. In fertile women, estradiol (E(2)), progesterone and gonadotrophins were also assessed.

RESULTS

In fertile women, luteal phase levels of plasma BDNF were significantly higher than follicular phase levels (P < 0.001). BDNF increased from early follicular phase up to Day 14 of the cycle, reaching a pre-ovulatory peak, similar to E(2). A second rise took place during mid-luteal phase, with a peak on Day 24. Amenorrhoeic subjects, as well as postmenopausal women, showed significantly lower plasma BDNF levels compared with fertile females (P < 0.001). BDNF was positively correlated with E(2) and progesterone and negatively correlated with menopausal age. HRT restored BDNF levels to those present in fertile women during the follicular phase.

CONCLUSIONS

Plasma BDNF levels are influenced by hormonal status. Modifications in BDNF circulating levels during the menstrual cycle suggest a potential role for gonadal sex hormones (E(2) and progesterone) in regulating neurotrophin expression.

Progesterone and progestins: effects on brain, allopregnanolone and beta-endorphin

The increased use of hormonal therapies over the last years has led to improve the knowledge of pharmacological, biochemical and metabolic properties of several progestins and their effects in target tissues, such as the central nervous system. Progesterone and synthetic progestational agents are able to modulate the synthesis and release of several neurotransmitters and neuropeptides in response to specific physiological and pathological stimuli. While these actions may relay on differential activation of progesterone receptor or recruitment of intracellular pathways, some of the differences found between synthetic progestins may depend on the specific conversion to neuroactive steroids, such as the 3-alpha, 5-alpha reduced metabolite, allopregnanolone. This is a potent endogenous steroid that rapidly affects the excitability of neurons and glia cells through direct modulation of the GABA-A receptors activity exerting hypnotic/sedative, anxiolytic, anaesthetic and anticonvulsive properties. Estrogens increase the CNS and serum levels of allopregnanolone and the addition of certain but not all synthetic progestins determines a further increase in allopregnanolone levels, suggesting that the metabolism into this reduced product is related to the chemical structure of progestin molecule used. In addition, depending on specific progestin molecule used, different interaction are found with the estradiol-induced beta-endorphin synthesis and release, showing that diverse progestins have specific and divergent actions on the opiatergic system. These results highlight the concept that natural and synthetic progesterone receptor agonists may systematically induce different biological actions in CNS. This may have far-reaching implications for the clinical effects and related indications of each compound.

Disadaptive disorders in women: allopregnanolone, a sensitive steroid

Allopregnanolone, a neurosteroid acting as a potent anxiolytic agonist of the gamma-aminobutyric acid A receptor, has been shown in animal models to modify its concentrations at central and peripheral levels according to the estrous cycle. Moreover, it modulates behavioral and biochemical responses to acute and chronic stress, anxiety, depression, aggressiveness, convulsions, anesthesia, sleep, memory, pain and feeding. These observations suggest that fluctuations of allopregnanolone might be involved in the development, course and prognosis of some mental disorders in humans. This has been hypothesized for depressive disorders, premenstrual dysphoria, anorexia and bulimia nervosa and Alzheimer's disease, where increased, decreased or dysregulated secretion of the main neurosteroids and their metabolites has been observed. Women show a marked gender-related sensitivity to disadaptive disorders. In addition to the well-studied role of sex steroids in modulating mood and behavior, a putative involvement of neurosteroid fluctuations, and in particular of allopregnanolone, has recently been hypothesized. In fact, several paraphysiological events and various disadaptive disorders in women are associated with modifications of circulating levels of this neurosteroid that might associated with a certain vulnerability to an altered adaptation to stressful life events.