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Evidence that long-term methionine-enkephalin administration stimulates rat adrenal zona fasciculata
Abstract:
Short-term methionine-enkephalin (DALA) treatment did not induce evident changes in the adrenal zona fasciculata and in the basal corticosterone output of dexamethasone-treated rats administered with maintenance doses of ACTH. Conversely, prolonged (5 days) DALA treatment caused a notable hypertrophy of zona fasciculata cells, along with a significant increase in the plasma concentration of corticosterone. It is suggested that enkephalins exert a trophic action on the rat zona fasciculata.
Insights
Short-term methionine-enkephalin (DALA) did not affect adrenal cells or corticosterone. However, prolonged DALA treatment led to adrenal zona fasciculata cell growth and increased corticosterone levels in rats.
Area of Science:
- Endocrinology
- Neuroscience
- Cell Biology
Background:
- The adrenal zona fasciculata produces corticosterone.
- Enkephalins are endogenous opioid peptides with various physiological roles.
- The effect of enkephalins on the adrenal cortex is not fully understood.
Purpose of the Study:
- To investigate the short-term and prolonged effects of methionine-enkephalin (DALA) on the rat adrenal zona fasciculata and corticosterone production.
Main Methods:
- Rats were treated with dexamethasone and ACTH to establish basal conditions.
- Short-term and prolonged (5 days) administration of DALA was performed.
- Adrenal zona fasciculata morphology and plasma corticosterone concentrations were assessed.
Main Results:
- Short-term DALA treatment showed no significant changes in zona fasciculata or basal corticosterone.
- Prolonged DALA treatment resulted in significant hypertrophy of zona fasciculata cells.
- Prolonged DALA treatment led to a significant increase in plasma corticosterone concentrations.
Conclusions:
- Enkephalins may exert a trophic action on the rat adrenal zona fasciculata.
- Prolonged exposure to enkephalins can stimulate corticosterone production.
- These findings suggest a potential role for enkephalins in regulating adrenal function.