Effects of Substance P on Anterior Pituitary Secretion in the Female Rhesus Monkey

Abstract

The effects of substance P on anterior pituitary secretion were studied in 3 female rhesus monkeys. In 9 experiments, 100 .mu.g substance P was injected intraventricularly, and the results were compared to those obtained following intraventricular injection of the control vehicle. In 7 of 9 experiments, substance P induced a significant increase in prolactin secretion within 5 min. Peak levels at 10 min were .apprx. 15-20 times those of the baseline control. Substance P also induced a slight but significant decrease in GH [growth hormone] secretion 20 min following injection, but at other times GH levels were not significantly changed. Lutropin, follitropin and cortisol concentrations remained unaltered. In 2 monkeys a decrease in systolic pressure of 40-70 mm Hg within 10-60 s and lasting 180-300 s was observed following the administration of substance P but not the control vehicle. Substance P, which in the monkey was associated with hypothalamic regions, implicated in the control of anterior pituitary secretion, apparently can alter prolactin and GH release.