Journal of Animal Science, Vol 72, Issue 2 464-469, Copyright © 1994 by American Society of Animal Science

JOURNAL ARTICLE

Effects of phenolic monoamines on release of luteinizing hormone stimulated by gonadotropin-releasing hormone and on plasma adrenocorticotropic hormone, norepinephrine, and cortisol concentrations in wethers

T. D. Forbes, B. B. Carpenter, R. D. Randel and D. R. Tolleson
Texas Agricultural Experiment Station, Uvalde 78801.

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 (T), 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). All treatments were given via indwelling jugular catheters in single doses of 2 mL. In Exp. 1, no effects of time after treatment on response were detected. The NMP2 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).(ABSTRACT TRUNCATED AT 250 WORDS)