EFFECTS OF PHENOLIC MONOAMINES ON RELEASE OF LUTEINIZING-HORMONE STIMULATED BY GONDATROPIN-RELEASING HORMONE AND ON PLASMA ADRENOCORTICOTROPIC HORMONE, NOREPINEPHRINE, AND CORTISOL CONCENTRATIONS IN WETHERS

Eighteen Suffolk and Suffolk x Hampshire wethers (56.3 +/- 1.3 kg) were used to determine the effects of naturally occurring amines, N-methyl-beta-phenethylamine (NMP) and tyramine CT), on plasma cortisol; norepinephrine (NE), ACTH, and GnRH-stimulated LH concentrations. In each experiment, wethers were assigned randomly to treatments with six replicates/treatment. In Exp. 1, treatments consisted of saline, 2 mg of NMP/kg BW (NMP2), or 4 mg of NMP/kg BW (NMP4). In Exp. 2, treatments consisted of saline, 4 mg of NMP/kg BW (N), or 2 mg of NMP + 4 mg of T/kg BW (NT). Al treatments were given via indwelling jugular catheters in single doses of 2 mt. In Exp. 1, no effects of time after treatment on response were detected. The NMPB wethers had lower cortisol and LH peak amplitudes (PKAMP) than other wethers (P <.03 and.05, respectively). Time to peak (PKT) concentration of NE was significantly shorter in NMP4-treated wethers (P < .004). In Exp. 2, significant interactions between time and treatment were detected for cortisol, NE, and LH. Cortisol and NE concentrations were increased (P < .0001 and P <.03, respectively) in N- and NT-treated wethers compared with controls, whereas LH was reduced (P <.003). The N and NT treatments increased cortisol PKT, peak height (PKHT), and PKAMP above that of controls (P <.02, <.006, and < .02, respectively). Time to LH peak did not differ between groups (P <.09), but PKHT and PKAMP were increased in control wethers (P <.001 and < .0001, respectively). Treated wethers had reduced NE PKT (P <.06). We conclude that there is a direct response to amine administration that occurs at the adrenal gland rather than indirectly via release of pituitary ACTH or stimulation of higher brain areas.