HORMONES AND MATING BEHAVIOR 



1205 



synergism between the estrogens and pro- 

 gesterone is encountered in both types of 

 tissue, and there is a consistency of species 

 differences in certain behavioral and tissue 

 responses to androgens (Gerall, 1958). To 

 the writer, one of the most impressive ex- 

 amples of this parallelism is the responses 

 of vaginal epithelium and the neural tissues 

 mediating mating behavior. In the guinea 

 |)ig, normal-appearing vaginal cornification 

 (Ford and Young, 1951 ) and normal mating 

 behavior are induced only when the ad- 

 ministration of an estrogen is followed by 

 progesterone. In the ewe, on the other hand, 

 there is a reversal of this relationshij). Nor- 

 mal vaginal responses are induced only 

 when an estrogen is preceded by progester- 

 one, and normal behavioral responses de- 

 lU'nd on the same sequence of hormonal ac- 

 tion (Robinson, Moore and Binet, 1956; 

 jNloore and Robinson, 1957). 



At the molar level we may be somewhat 

 l)etter off, because the search for the neural 

 correlates of sexual behavior has been a sub- 

 ject of research in many laboratories (see 

 reviews by Beach, 1942e,"j, 1943, 1947, 1948, 

 1951, 1958; and the recent articles by Harris, 

 Michael and Scott, 1958; Kawakami and 

 Sawyer, 1959a; Sawyer and Kawakami, 

 1959). In considering what has been accom- 

 plished and the problems, it is well to start 

 with the suggestion contained in a number 

 of the articles cited above that in the male 

 and female two different mechanisms are in- 

 volved. The significance of this fact, if it 

 may be so regarded, is that the emergence 

 of a single explanation, applicable to the 

 two sexes, for the mechanism of action of 

 the gonadal hormones in bringing sexual be- 

 havior to expression is unlikely. 



The evidence for the suggestion that two 

 mechanisms are involved comes from many 

 sources. It has long been held that the neural 

 mediators of sexual behavior in male mam- 

 mals are different from those in females 

 (Beach, 1942e, 1943, 1951, 1958). The neo- 

 cortex is more heavily involved in mating 

 performance in the male than in the female. 

 As we noted earlier, the disappearance or 

 reduction of mating behavior after hormonal 

 withdrawal is gradual rather than abrupt 

 in the male, whereas it is abrupt in the fe- 

 male. When replacement therapy is given. 



the restoi'ation of mating behavior is slow in 

 the male rather than inmiediate, as it is in 

 the female. In males a single chemical sub- 

 stance, an androgen, is effective in maintain- 

 ing sexual behavior, but in females of many 

 species two substances, an estrogen and pro- 

 gesterone are involved. In the female ral)bit, 

 EEG arousal thresholds have been corre- 

 lated with mating behavior, but in males sex 

 drive could not be correlated with arousal 

 thresholds (Kawakami and Sawyer, 1959). 

 Whether the female or male is being in- 

 vestigated, some knowledge of the time re- 

 quired for the hormones to exert their ef- 

 fects, coupled with information bearing on 

 the temporal and qualitative aspects of gon- 

 adal hormone metabolism would be impor- 

 tant in any analysis of the mechanisms of 

 hormonal action. When females were being 

 studied it became clear that up to 24 hours 

 elapse after the injection of an estrogen be- 

 fore the animals are conditioned to respond 

 to progesterone. The latter substance, on 

 the other hand, w^as effective in an average 

 of about 5 hours (Collins, Boling, Dempsey 

 and Young, 1938; Boling and Blandau, 1939; 

 Frank and Fraps, 1945). Inasmuch as both 

 hormones were contained in the same oily 

 vehicle and injection was subcutaneous, 

 more than a matter of transport from the site 

 of injection must be involved. This consider- 

 ation is emphasized by the results obtained 

 when estrogens were placed directly on the 

 reactive tissue in the case of the vagina, or 

 on what is believed to be the reactive tissue 

 in the case of the brain. After intravaginal 

 administration of estrone, the mitotic ac- 

 tivity of the epithelial cells did not begin 

 until after a latent period of 12 hours (Big- 

 gers and Claringbold, 1955). Whether the 

 administration of estrogen to female cats 

 was subcutaneous or direct in the posterior 

 hypothalamus, the latent period to mating 

 was at least 3 days (Harris, Michael and 

 Scott, 1958). The slower and more gradual 

 action of androgens might handicap a worker 

 seeking to learn something about the tem- 

 poral relationships between hormone and re- 

 sponse in the male. Nevertheless, in the male 

 as in the female the interval before overt 

 responses can be elicited may well exceed (1) 

 the time required for the transport of effec- 

 tive quantities of tlie hormones to the tissues 



