RESUMO
Two weeks after bilateral lesions in the dorsal and ventral hippocampus, septum, and basolateral amygdala, plasma concentrations of ACTH, TSH, corticosterone, aldosterone, and thyroxine were determined in 5-6 month-old (adult) and 24-26-month-old (aged) male Wistar rats. The results indicate that with age, limbic system control over the hypothalamic-pituitary- adrenal/thyroid axes changes, although these changes are not uniform. Thus, the inhibitory influences of the dorsal/ventral hippocampus and septum on ACTH release tend to diminish as age increases. However, the inhibitory influence of the amygdala on ACTH appears to become enhanced during the aging process. The data also support an enhanced sensitivity of the adrenal cortex to ACTH during aging. In adult animals, lesions of the dorsal/ventral hippocampus and amygdala result in significantly decreased plasma concentrations of TSH consistent with a stimulatory influence of these regions on TSH release. Lesions in the septum, however, lead to significantly increased TSH secretion in these animals. To these finding, lesions of the dorsal/ventral hippocampus and amygdala in aged animals resulted in significantly increased TSH secretion, while results of septal lesions were not significant.
Assuntos
Envelhecimento/fisiologia , Glândulas Endócrinas/fisiologia , Sistema Límbico/fisiologia , Hormônio Adrenocorticotrópico/metabolismo , Aldosterona/metabolismo , Tonsila do Cerebelo/fisiologia , Animais , Corticosterona/metabolismo , Hipocampo/fisiologia , Sistema Hipotálamo-Hipofisário/fisiologia , Masculino , Sistema Hipófise-Suprarrenal/fisiologia , Ratos , Ratos Wistar , Septo Pelúcido/fisiologia , Glândula Tireoide/fisiologia , Tireotropina/metabolismo , Tiroxina/metabolismoRESUMO
The concentration of sex and gonadotropic hormones in blood plasma of 280 reasonably healthy men aged 20-105 was determined using radioimmunoassay kits. Compared to men aged 20-39, the statistically significant decrease in testosterone level was registered in men aged 55-59, the increase in oestradiol in men aged 60-64, progesterone in men aged 55-59, and in LH and FSH in the group aged 65-69. The reactivity of central and peripheral links of the hypothalamic-gonadal system to direct and feed-back control influences alters with age.
Assuntos
Envelhecimento , Hormônios Esteroides Gonadais/sangue , Gonadotropinas Hipofisárias/sangue , Adulto , Idoso , Gonadotropina Coriônica/farmacologia , Estradiol/sangue , Hormônio Foliculoestimulante/sangue , Humanos , Hormônio Luteinizante/sangue , Masculino , Pessoa de Meia-Idade , Testes de Função Hipofisária , Progesterona/sangue , Testículo/efeitos dos fármacos , Testosterona/sangueAssuntos
Acetilcolina/metabolismo , Envelhecimento , Animais , Pré-Escolar , Humanos , Lactente , RatosRESUMO
The experiments on adult (4-6 months) and old (28-30 months) rats revealed changes that develop in old age in various links of the regulatory system of aldosterone secretion: the hypothalamic-hypophyseal control of mineralocorticoid secretion decreased, and the sensitivity of the glomerular zone to ACTH, vasopressin, and K+, as well as that of the myocardium, skeletal muscle and kidney to aldosterone increased. Changes in tissue sensitivity to aldosterone may be due to the increased affinity of mineralocorticoid receptors to aldosterone in old age.
Assuntos
Envelhecimento , Aldosterona/metabolismo , Córtex Suprarrenal/fisiologia , Animais , Feminino , Sistema Hipotálamo-Hipofisário/fisiologia , Rim/citologia , Rim/metabolismo , Masculino , Mineralocorticoides/fisiologia , Potássio/metabolismo , Ratos , Ratos Endogâmicos , Receptores de Glucocorticoides/metabolismo , Receptores de Mineralocorticoides , Fatores Sexuais , Sódio/metabolismoRESUMO
Changes in hemodynamics and myocardial contractile capacity following the stimulation of extracardial nerves and administration of various doses of acetylcholine, norepinephrine, propranolol, phentolamin, atropine, serpasil and benzohexonium were studied in albino rats, rabbits and cats of various age. The shifts in cardiac acetylcholine and norepinephrine content and the activity of some enzymes of their catabolism were determined as well. Functional changes were compared with the structural shifts in intramural nervous system. In old animals there was a rise in threshold of voltage, which induced threshold reaction at stimulation of n. vagus and n. sympaticus and there was a change in heart sensitivity to acetycholine and norepinephrine, propranolol, atropine, serpasil and benzohexonium. A relationship was shown between age changes in nervous regulation of heart and transmitter metabolism. The intensity of acetylcholine and norepinephrine synthesis was decreased in old age, the transmitter metabolism in various parts of the heart was not uniformly altered, the sensitivity of epicardial chemoreceptors to nicotine, veratrum, acetylcholine was increased. The reflexes from cardiac mechanoreceptors were diminished.
Assuntos
Envelhecimento , Coração/fisiologia , Neurotransmissores/metabolismo , Acetilcolina/metabolismo , Acetilcolina/farmacologia , Animais , Gatos , Células Quimiorreceptoras/fisiologia , Coração/inervação , Sistema de Condução Cardíaco/anatomia & histologia , Sistema de Condução Cardíaco/fisiologia , Hemodinâmica/efeitos dos fármacos , Mecanorreceptores/fisiologia , Contração Miocárdica/efeitos dos fármacos , Miocárdio/metabolismo , Norepinefrina/metabolismo , Norepinefrina/farmacologia , Coelhos , Ratos , Sistema Nervoso Simpático/fisiologia , Nervo Vago/fisiologiaRESUMO
Experiments on adult (6-8 months) and old (24-28 months) male rats under chronic emotional-pain stress showed that in aging the reliability of the control system of corticosterone secretion remains unchanged while that of aldosterone secretion decreased.