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The cyclic AMP-dependent protein kinase (PKA) has been involved in the brain aging process and recent papers have reported age-associated changes in enzyme activity in rat brain. The present study was undertaken to assess simultaneously PKA activity and regulatory (R) subunit levels during maturation and aging. Five cohorts of rats of different ages were(More)
Estrogen formed by aromatization of testosterone (T) is involved in the activation of sexual behavior and control of the neuroendocrine system in the male Syrian hamster. Our study examined whether daylength influences formation of estrogen in the preoptic area (POA) and other neuroendocrine areas (anterior hypothalamus, AHT, and medial amygdala, MA) which(More)
The preoptic area (POA) of the male dove is a known target area for separable behavioral actions of testosterone and 17 beta-estradiol (E2) and contains an active aromatase system. We have examined the regulatory influence of gonadal hormones on aromatase using an in vitro microassay that measures conversion of [1 alpha, 2 alpha-3H]testosterone to E2 in(More)
In vitro experiments were conducted to compare the steroid regulation of aromatase in preoptic and posterior hypothalamic areas. Kinetic analysis of aromatase activity in the preoptic area (POA) and posterior hypothalamus (AHP) of castrated and intact doves indicate that both areas have a similar, high substrate affinity (apparent Km less than 15 nM), but(More)
The preoptic area (POA) of the male ring dove is a target for specific behavioral effects of estrogen that are separable from those of androgen. Activity of the aromatase system in the POA, which converts testosterone to 17 beta-estradiol (E2), is increased by systemic androgen. Using crystalline steroid implants positioned stereotaxically in the brain, we(More)
In vitro study of testosterone (T) metabolism shows that formation of 17 beta-oestradiol (E2) in the preoptic area is higher in male doves exposed to behavioural stimuli from interacting pairs than in visually isolated males or males that have interacted with females. Formation of 5 alpha-dihydrotestosterone, 5 beta-dihydrotestosterone and 5(More)
The aim of the study was develop to an animal model that links coping style to insulin resistance. We hypothesized that the psychogenetically selected Roman Low Avoidance (RLA) rats may serve as such a model. To test this hypothesis, we submitted both RLA and Roman High avoidance (RHA) rats to a series of intravenous glucose tolerance tests (IVGTT). These(More)
Testosterone is converted in the dove (Streptopelia risoria) brain to 5 beta-reduced metabolites that do not affect behavior. In long-term castrated birds, which are relatively insensitive to the behavioral effects of testosterone, the activity of preoptic 5 beta-reductase is increased. The increase, which is specific to the preoptic area, is reversed by(More)