Testosterone-dependent primer pheromone production in the sebaceous gland of male goat

To test the hypothesis that the primer pheromone responsible for inducing t he "male effect" is produced in the sebaceous gland androgen dependently, w e examined the correlation between morphological changes of sebaceous gland s and the pheromone activity in skin samples taken from castrated goats tha t had been treated with testosterone. Five castrated goats were implanted s .c. with testosterone capsules to maintain physiological levels of plasma t estosterone for four weeks. Skin samples were obtained from the head region on Day 0 (the day of testosterone implant), Day 7, Day 14, Day 28 (the day of testosterone removal), Day 36, Day 42, and Day 56, Matched blood sample s were also collected for measurement of testosterone concentration. The ph eromone activity of the ether-extracts of the upper dermal layer containing sebaceous glands was assessed by its stimulatory effect on the hypothalami c GnRH pulse generator, which was monitored for changes of specific multipl e unit activity (MUA) in ovariectomized estradiol-primed goats as described previously. The sebaceous gland enlarged during the testosterone treatment but reduced in size after testosterone removal. The pheromone activity fir st appeared in 2 out of 5 goats on Day 7 and in all the 5 goats by Day 28. Fourteen days after testosterone removal (Day 42), the pheromone activity w as no longer detectable in any of the 5 goats. In short, the sebaceous glan d size and the pheromone activity shifted almost in parallel. The present r esults provide strong support for the view that the primer pheromone is pro duced testosterone dependently in the sebaceous gland of the male goat.