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The aim of the present experiment was to study the effects of early postnatal maternal separation on behavioural and adrenocortical responses to novelty in rats tested as adults. Sprague-Dawley rat pups were exposed to daily maternal separation (5 h/day) from postnatal day 2 to 6, during the stress hyporesponsive period. Since this procedure requires physical contact with the animals, a first control group of daily handled pups was introduced. A second control group, consisting of pups never handled or separated from the mother, was also considered. At postnatal day 45, the rats were tested in a two-compartment exploratory apparatus: the maternally separated and the non-handled rats, whose behavioural performance did not differ, showed higher emotional behaviour when compared with the handled rats (P < 0.05), suggesting that the handling procedure but not maternal separation improved the capacity to cope with novelty. Corticosterone plasma levels were found to be higher in the maternally separated rats than in the other two groups (P < 0.05), either at resting conditions or at 30 min after novelty exposure (P < 0.05). Levels of nuclear glucocorticoid receptor immunoreactivity in the CA1 hippocampal field were shown to be regulated by novelty exposure, as expected, in both the handled and the non-handled rats but not in the maternally separated rats. In conclusion, repeated maternal separation periods of 5 h/day during the first week of life produced long-lasting effects on the hippocampal regulation of the hypothalamic-pituitary-adrenocortical axis, which appear to be associated with increased responsiveness to stress stimuli in adulthood.

Neuropeptide Y (NPY) plays an important role in stress, anxiety, obesity, and energy homeostasis via activation of NPY-Y1 receptors (Y1Rs) in the brain. However, global knockout of the Npy1r gene has low or no impact on anxiety and body weight. To uncover the role of limbic Y1Rs, we generated conditional knockout mice in which the inactivation of the Npy1r gene was restricted to excitatory neurons of the forebrain, starting from juvenile stages (Npy1r rfb ). Npy1r rfb mice exhibited increased anxiety and reduced body weight, less adipose tissue, and lower serum leptin levels. Npy1r rfb mutants also had a hyperactive hypothalamic-pituitaryadrenocortical axis, as indicated by higher peripheral corticosterone and higher density of NPY immunoreactive fibers and corticotropin releasing hormone immunoreactive cell bodies in the paraventricular hypothalamic nucleus. Importantly, through fostering experiments, we determined that differences in phenotype between Npy1r rfb and Npy1r 2lox mice became apparent when both genotypes were raised by FVB/J but not by C57BL/6J dams, suggesting that limbic Y1Rs are key targets of maternal care-induced programming of anxiety and energy homeostasis. where it is involved in the regulation of anxiety, stress reactions, energy balance, circadian rhythms, and cognition (1-3). Clinical studies suggest that NPY plays an important role in the response to stress and in psychiatric disorders (4). In humans, NPY haploinsufficiency is correlated with characteristic brain responses to emotional and stress challenges and with trait anxiety (5). Intracerebroventricular injection of NPY reduces both anxiety-and stress-related behavior in several animal models, an effect that is primarily mediated by Y1 receptors (Y1Rs) expressed in amygdala, hippocampus, and locus coeruleus (6-9). The implications of a role of endogenous NPY in acting via Y1R to control emotionality, mood, and stress reactions have been probed with Y1R-selective antagonists and antisense oligonucleotides (1). NPY exerts its anxiolytic-like effect in the brain via interactions with the hypothalamic-pituitaryadrenocortical (HPA) axis and corticosteroids. Indeed, a functional antagonism between NPY and corticotropin releasing hormone (CRH) has been demonstrated in various CNS nuclei along the stress/anxiety circuits (10).In addition to its crucial role in emotional behavior, NPY potently stimulates feeding, reduces energy expenditure, and induces obesity via the activation of Y1R expressed in the hypothalamus (1). However, global Npy1r gene knockout mice showed only minor deficiencies in energy homeostasis, feeding, and anxiety (11)(12)(13)(14).To study the function of Y1R expressed in the limbic system and to exclude effects induced by the Npy1r gene inactivation in early development, we restricted the ablation of Y1R to excitatory neurons in the postnatal forebrain of mice by using the Cre-loxP system (Fig. 1A). In addition, because early postnatal environment can modulate NPY levels (15), gene-targeted pups were reared by two diffe...

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The circadian rhythms of serum luteinizing hormone, follicle-stimulating hormone, testosterone (T), free testosterone (fT), sex hormone-binding globulin (SHBG), oestradiol, cortisol and dehydroepiandrosterone sulphate (DHA-s) have been investigated in 5 normal male adults and 6 elderly men. Circadian rhythms were detected statistically significant (p < 0.05) by population mean cosinor analysis, for T, fT, cortisol and DHA-s in the young group. In the elderly population, serum cortisol showed a clear circadian rhythm, although with some phase modification, whereas DHA-s secretion lost its circadian rhythmicity. This demonstrates that ageing differently affects the two major adrenal functions, glucocorticoid and androgenic; further, the data suggest that an independent adrenal androgen-regulating system could be selectively impaired in the older subjects. In the elderly group the loss of T circadian rhythm was confirmed, but a statistically significant circadian rhythm of fT was recorded. It was characterized by a marked phase advance and not related with the SHBG modifications found in elderly men. This finding leads us to reconsider the role of fT, which appears more sensitive than total T, in studying circadian rhythm of gonadal androgen secretion.

The relation between sexual function and serum free testosterone (fT) levels, which represent the active fraction of circulating testosterone, was evaluated. Two groups of impotent male subjects with mild hypogonadism were treated with oral testosterone undecanoate (TU); these men presented with tT/luteinizing hormone (LH) ratio and tT levels at the lower limits of normal. The first group had serum fT below 6.6 ng/ml, considered the lower normal value, according to our laboratory method, whereas the second group had normal fT limits. Administration of TU improved sexual function only in impotent men with low fT levels, but not in subjects with normal fT levels, even though the tT levels and the tT/LH ratio of the two groups were not significantly different. The results of our study suggest the presence of a minimum serum fT threshold, lying near the lower normal range, which determines the male sexual function. Moreover, serum fT levels were a more sensitive index than tT for identifying impotent men who can be successfully treated with androgens.

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Eleven adult males, previously submitted to neurosurgery because of a pituitary lesion (three with craniopharyngioma, three with clinically non-functioning adenoma and five with macroprolactinoma) were treated with recombinant GH for 12 months after the diagnosis of GH deficiency was made. Circulating FSH, LH, prolactin, testosterone, 17b-estradiol (E 2 ), dehyroepiandrosterone (DHEA-S), androstenedione, 17-OH-progesterone (17OHP), IGF-I, and steroid hormone-binding protein (SHBG) levels were assayed before and after CG test at study entry and 6 and 12 months after GH treatment.A significant increase in plasma IGF-I levels was obtained after 6 and 12 months of GH treatment. In addition, CG-stimulated, but not baseline, testosterone levels showed a significant increase after 6 and 12 months of GH treatment when compared with study entry (9.6Ϯ0.5 and 9.9Ϯ0.5 vs 7.9Ϯ0.5 ng/ ml; P<0.05). Baseline, but not CG-stimulated, serum 17OHP levels were significantly increased only after 12 months of GH treatment (1.7Ϯ0.1 vs 1.4Ϯ0.1 ng/ml; P<0.05). No significant difference was found as far as both basal and CG-stimulated E 2 , androstenedione, DHEA-S and SHBG were concerned. With regards to the semen analysis, only seminal plasma volume was significantly increased after 12 months of GH treatment (2.9Ϯ0.3 vs 1.7Ϯ0.3 ml; P<0.05). No significant change in sperm count, motility and abnormal forms was observed.These data show that GH treatment displays a clear-cut effect upon Leydig cell function and increases the production of seminal plasma volume in fertile adult males with isolated GH deficiency.