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INFLUENCE OF CHLORDIMEFORM ON ALPHA-ADRENERGIC RECEPTOR-ASSOCIATED MECHANISMS OF HORMONAL REGULATIONS: PITUITARY AND ADRENOCORTICAL SECRETION
Citation:
Stoker, T., J. Goldman, R. Cooper, AND W. McElroy. INFLUENCE OF CHLORDIMEFORM ON ALPHA-ADRENERGIC RECEPTOR-ASSOCIATED MECHANISMS OF HORMONAL REGULATIONS: PITUITARY AND ADRENOCORTICAL SECRETION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/018.
Description:
The acaricide chlordimeform (CDF) has been reported to have effects on the central nervous system that appear to involve an interaction with adrenergic receptor mediated mechanisms of neurotransmission. The present study examined the influence of CDF on pituitary-adrenocortical hormonal secretion, since there is a well-established a-adrenoceptor component to this activity. ffects on prolactin (PRL) were also evaluated, as its release is often concurrent with adrenocortical hormonal secretion and may involve an adrenergic contribution. DF-injected (20 or 50mg/kg) male Long-Evans rats were killed after 1,4,8 or 24 hrs. oth non-injected and saline-injected controls were included. osing was structured so that trunk blood could be collected during the morning nadir of circulating corticosterone (CORT). Plasma adrenocorticotropic hormone (ACTH), CORT, and PRL all increased sharply by 1 hr following 50mg/kg CDF. ORT increased in a dose-dependent fashion and declined over the ensuing 8 hrs. Separate groups of animals were also pre-treated with the adrenoceptor antagonist phenoxybenzamine (PBZ 20mg/kg) or the a-receptor against clonidine (CLON, 0.6mg/kg) 40 min before and killed 1 hr after CDF (25mg/kg) injection. LON completely suppressed the CDF-induced rise in CORT, while PBZ enhanced the CORT/ACTH response to CDF. LON also significantly elevated EEL an alteration not seen in the CLON-pretreated CDF rats.