Hormones and behavior
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Hormones and behavior · Jan 2013
Voluntary exercise does not ameliorate spatial learning and memory deficits induced by chronic administration of nandrolone decanoate in rats.
Chronic exposure to the anabolic androgenic steroids (AAS) nandrolone decanoate (ND) in supra-physiological doses is associated with learning and memory impairments. Given the well-known beneficial effects of voluntary exercise on cognitive functions, we examined whether voluntary exercise would improve the cognitive deficits induced by chronic administration of ND. We also investigated the effects of ND and voluntary exercise on hippocampal BDNF levels. ⋯ These results seem to indicate that voluntary exercise is unable to improve the disruption of cognitive functions by chronic ND. Moreover, increased levels of BDNF may play a role in ND-induced impairments in learning and memory. The harmful effects of ND and other AAS on learning and memory should be taken into account when athletes decide to use AAS for performance or body image improvement.
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Hormones and behavior · Jan 2013
17β-Estradiol, but not estrone, increases the survival and activation of new neurons in the hippocampus in response to spatial memory in adult female rats.
Estrogens fluctuate across the lifespan in women, with circulating 17β-estradiol levels higher pre-menopause than estrone and circulating estrone levels higher postmenopause than 17β-estradiol. Estrone is a common component of hormone replacement therapies, but research shows that 17β-estradiol may have a greater positive impact on cognition. Previous studies show that acute estrone and 17β-estradiol impact hippocampus-dependent learning and cell proliferation in the dentate gyrus in a dose-dependent manner in adult female rats. ⋯ However, the 17β-estradiol group had significantly higher, while the estrone group had significantly lower, levels of cell survival (BrdU-ir cells) in the dentate gyrus compared to controls. Furthermore, rats injected with 17β-estradiol showed significantly higher levels of activation of new neurons in response to spatial memory compared to controls. These results provide insight into how estrogens differentially influence the brain and behavior, and may provide insight into the development of hormone replacement therapies for women.
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Hormones and behavior · Sep 2012
Controlled Clinical TrialSocial subordination impairs hypothalamic-pituitary-adrenal function in female rhesus monkeys.
Linear dominance hierarchies organize and maintain stability in female rhesus macaque (Macaca mulatta) social groups regardless of group size. As a consequence of their low social status, subordinate females suffer from an array of adverse outcomes including reproductive compromise, impaired immune function, and poor cardiovascular health. However, data that differentiate limbic-hypothalamic-pituitary-adrenal axis (LHPA) parameters between dominant from subordinate female monkeys are inconsistent, bringing into question whether social subordination alters the LHPA axis in female macaques. ⋯ Compared to dominant females, subordinate females showed diminished morning peak cortisol secretion, weakened glucocorticoid negative feedback, and decreased adrenal cortisol response to an ACTH challenge as well as a restrained cortisol response following social isolation. However, the metabolism of Dex did not account for differences in Dex suppression between dominant and subordinate females. These results indicate that the ability to mount and limit glucocorticoid release is significantly reduced by psychosocial stress in female rhesus macaques, suggesting a hyporesponsive LHPA phenotype which resembles that observed in several human psychopathologies.
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Hormones and behavior · Jun 2012
Concurrent attenuated reactivity of alpha-amylase and cortisol is related to disruptive behavior in male adolescents.
Attenuated reactivity of salivary alpha-amylase has been proposed as a specific sympathetic marker of disruptive behavior in juveniles and may have additional value to studying other autonomic parameters and hypothalamic-pituitary-adrenal axis activity. Investigating the interrelationships between neurobiological parameters in relation to juvenile disruptive behavior may enhance insight into the complex mechanisms at play. We investigated salivary alpha-amylase, cortisol, heart rate (HR), and heart rate variability (HRV) in response to a standardized public speaking task, and examined interactions between these parameters in relation to disruptive behavior. ⋯ Attenuated alpha-amylase responsivity to stress is a correlate of disruptive behavior in late-adolescent males. Although nicotine use explains a considerable part of the variance of disruptive behavior, both alpha-amylase and cortisol are related to disruptive behavior, over and above the effect of nicotine use. Combining alpha-amylase and cortisol improved insight into neurobiological mechanisms involved with disruptive behavior; concurrent low reactivity of both parameters was related to higher levels of disruptive behavior.
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Hormones and behavior · Jun 2012
Genetic and environmental influences on individual differences in cortisol level and circadian rhythm in middle childhood.
Individuals differ widely in cortisol output over the day, but the etiology of these individual differences remains poorly understood. Twin studies are useful for quantifying genetic and environmental influences on the variation in cortisol output, lending insight into underlying influences on the components of Hypothalamic-Pituitary-Adrenal (HPA) axis functioning. Salivary cortisol was assayed on 446 twin pairs (157 monozygotic, 289 dizygotic; ages 7-8). ⋯ In contrast, additive genetic variation did not significantly contribute to variation in afternoon-to-evening slope. Third, the majority of variance in cortisol concentration was associated with shared family environments. In summary, both genetic and environmental factors influence cortisol's circadian rhythm, and they do so differentially across the day.