To test the hypothesis that the primer pheromone responsible for inducing the "male effect" is produced in the sebaceous gland androgen dependently, we examined the correlation between morphological changes of sebaceous glands and the pheromone activity in skin samples taken from castrated goats that had been treated with testosterone. Five castrated goats were implanted s.c. with testosterone capsules to maintain physiological levels of plasma testosterone 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 samples were also collected for measurement of testosterone concentration. The pheromone activity of the ether-extracts of the upper dermal layer containing sebaceous glands was assessed by its stimulatory effect on the hypothalamic GnRH pulse generator, which was monitored for changes of specific multiple 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 first 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 was no longer detectable in any of the 5 goats. In short, the sebaceous gland size and the pheromone activity shifted almost in parallel. The present results provide strong support for the view that the primer pheromone is produced testosterone dependently in the sebaceous gland of the male goat.
The community cats program (CCP), which includes trap–neuter–return activities, has been promoted in Japan to reduce the population of free-roaming cats without harmful effects on their welfare. To ascertain the effects of the CCP, a two-year route census of free-roaming cats was conducted in an area with CCP and the other area without CCP in urban Tokyo, Japan. The estimated number of cats was lower in the CCP area than the non-CCP area, but there was no difference in the rate of decline in cat populations between areas. More cats emigrated or disappeared rather than immigrated in both areas in the second year and more males tended to immigrate into the CCP area. There was no difference in the behavior of cats between areas and among seasons. The proportion of cats with poor health was lower in the CCP area than the non-CCP area. These results suggest that the CCP may improve the welfare of free-roaming cats. As the effect of CCP was restrictive in reducing the population of free-roaming cats, the further promotion of neutering of cats may be necessary to reduce the population density of cats.
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