Adrenocortical influence on histokinetics and lipid components of uropygial gland of immature chick.

Adrenocortical influence on uropygial gland of 10-day old male white leghorn chicken was assessed by suppressing glucocorticoid level with metyrapone and following corticosterone and deoxycorticosterone acetate (DOC) treatments (im), 100 micrograms each on alternate day for a period of 15 days. Metyrapone treatment resulted in significant atrophy of the uropygial gland with a severe regression of the glandular alveoli due to cytopycnosis, cellular disintegration and drastic cell loss. Concomitantly, there was a depletion of glandular lipid and its diester wax fraction. Corticosterone, administered simultaneously with metyrapone, counteracted severe adverse effects of the latter on the uropygial gland. In the normal chicken also corticosterone alone caused glandular hypertrophy with increased rate of cell renewal and cell growth within the alveoli and, to a lesser extent, augmented output of the glandular lipids. Simultaneous administration of corticosterone and testosterone propionate (TP), on the other hand, caused a moderate suppressive influence on this gland. DOC treatment alone or with metyrapone and TP failed to exert any noteworthy change in the uropygial gland excepting a moderate reduction of gland weight and a rise of glandular lipids observed after combined injections of DOC with TP and with metyrapone respectively.

ß-Lipotropin/adrenocorticotropic hormone responses to corticotropin releasing hormone, hypoglycemia, metyrapone and dexamethasone in normal human subjects

1. The possible correlation between secretions of adrenocorticotropic hormone (ACTH) and of ß-lipotropin (ß-LPH), two pro-opiomelanocortin (POMC)-derived peptides, was investogated in 27 normal subjects under basal conditions (circadian rhythmz0, after the administration of 1 mg dexamethasone and in tests involving acute (human corticotropin releasing hormone, hCRG, and insulin tolerance test, ITT) and chronic (metyrapone) simulation. 2. All subjects presented circadian rhythm and an operating negative feedback mechanism. Plasma ACTH and ß-LPH concnetrations were correlated in al tests. The increase in ACTH and ß-LPH levels after hCRH was lower than that detected after ITT, though both increases were more discrete than those detected after stimulation with metyrapone. 3. The data suggest that, under hypoglycemic conditions, ACTH and ß-LPH secretion involves other POMC secretagogues in addition to endogenous CRH. The batyre of these factore remains undefined. The greater efficacy of metyrapone treatment in elevating ACTH and ß-LPH levels is most likely mediated by sustained reduction in cortisol production and interrruption of the rapid steroid feedback on the pituitary. The molar peak ratios of the acute tests, vere similar to one another, differed from the peak ratio obtained during the metyrapone test, suggesting that corticotrophs may present polls with differentiated ACTH and ß-LPH content and release according to the type and/or duration of the stimulus

Effect of dexamethasone and metopirone on hypothalamic gamma-aminobutyric acid (GABA) and plasma cortisol levels in the female catfish, Clarias batrachus (L.)

Em C. batrachus, o GAMA hipotalâmico aumentou significativamente em resposta ao tratamento durante 7 dias com dexametasona (50 ug/peixe/dia : i.p.). Entretanto, a metopirona (CIBA, 50 ug/peixe/dia : i.p.) baixou acentuadamente o conteúdo do GABA hipotalâmico já a partir do 3. dia de tratamento. Nos peixes submetidos a tratamentos com dexametasona e metopirona o nível de cortisol plasmático apresentou-se significativamente menor. Estes resultados sugerem que o aumento e decréscimo dos níveis do GABA hipotalâmico podem ter um papel estimulador ou inibidor em resposta aos tratamentos com dexametasona ou metopirona