Role of the Gonads in Control of Blood Pressure in Chickens

Blood pressure changes in gonadectomized and gonadotrophin-treated chicks were utilized to determine the role of the gonads in establishing and maintaining the sex difference in pressure of the adult chicken. By the 23rd week, 4–5 weeks after the normal rise in male pressure, both capon and poulard pressures had climbed to near the male level and significantly above the female. This confirms that androgen is not essential to the rise in pressure, and indicates that other than ovarian activity, nothing inherent in the female prevents the rise. Furthermore, elevated poulard pressures could be depressed to near female levels with estrogen or 2-amino,5-nitrothiazole, presumably through suppression of pituitary gonadotrophin secretion. Exogenous gonadotrophin failed to change the pressure of the chick prematurely, despite marked sexual stimulation, suggesting that chronological maturation, possibly independent of the pituitary-gonad interrelationship, is a prerequisite.