Effects of LH, FSH, Prolactin and PGF2α on Testicular Blood Flow and Testosterone Secretion in the Ram

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Abstract
Five unilaterally castrated rams had Doppler blood flow transducers fitted onto the testicular artery. All rams were injected with saline, LH, FSH, prolactin and prostaglandin (PG)F2α in an experiment with a Latin square design. On each test day, measurements of blood flow in the testicular artery and samples of jugular venous blood for hormone analyses were taken at 15-min intervals for 2 hr before and 4 hr after the first injection. No treatment affected blood flow in the testicular artery although blood levels of LH, testosterone, FSH and prolactin were greatly increased. Injection of PGF2α had a variable effect on LH release; if LH concentration increased, a release of testosterone was detected. Blood flow also was unaltered during spontaneous, episodic increases of serum testosterone concentration. Thus, we conclude that changes in production and secretion of testosterone following LH stimulation of Leydig cells are not associated with changes in total blood flow to the testis. Rams were exposed to estrous ewes and flow in the testicular artery was monitored continuously. There was an increase in testicular blood flow associated with mounting, intromission or ejaculation. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.