雌ザルの性行動およびgroomingに対する視床下部電気刺激の効果を調べた。視床下部腹内側核への1回のトレイン刺激(持続0.5 ms,頻度、50 Hz, パルス数125)に対応してpresentiR9が誘発できた。このトレイン刺激を10秒ごとに30回繰り返すと、視床下部腹内側核に加え、内側視束前野の刺激でもpresentingが誘発できた。一方、視束前野から視床下部後部のいくつかの部位の刺激により、雄に対するgroomingが誘発できた。以上の結果は、(1)視床下部の異なった部位が雌ザルのpresentingとgroomingに関与していること、(2)視束前野と視床下部腹内側核はpresentingの発現に異なった様式で関与していることを示す。
Koyama, Y.1*, Fujita, I.1, Nishino, H.1,2 and Oomura, Y1,3
1 Natl. Inst. Physiol. Sci., Okazaki 944;
2 Toyama Med. Pharmaceut. Univ., Toyama 930-01;
3 Dept. Pysiol., Fac. Med., Kyusyu Univ., Fukuoka 812 (Japan)
Proceptivity (active solicitation from female) and receptivity (passive response to male sexual behavior) are basic components of sexual behavior in female mammals. Although the neural mechanisms of the female receptivity were intensively studied, especially in rats, little is known about the neural mechanisms underlying proceptivity. Neural substrate of allogrooming, a type of social behaviors which has close relation to sexual behavior, also remains to be identified. In this experiment, we examined effects of electrical stimulation of the hypothalamus on proceptive presenting and allogrooming in ovariectomized, estrogen-treated female monkeys (Macaca mulatta) kept and used in accordance with the NIH Guide (1985). Cathodal rectangular pulses (0.5 ms, 50 Hz, 2.5 sec) were applied to various sites in the hypothalamus . Single train stimuli of 160 to 300 uA to the ventromedial hypothalamic nucleus (VMH) elicited presenting without the prior touching by the male. Similar single train stimuli up to 500 μA to the medial preoptic area (MPOA) did not evoke presenting. However, twenty to thirty repetitive train stimuli of 200 μA to this area elicited presenting . Single train stimuli of 30 to 300 μA to the lateral preoptic area (LPOA), lateral hypothalamic area (LHA) or dorsomedial hypothalamic nucleus (DMH) elicited allogrooming. These electrically evoked behaviors cannot be considered as simple somatic reflexes or arm extensions, because when the partner was separated, or replaced with a non-living object or an experimenter, neither presenting nor allogrooming was evoked. Our results provide the first evidence for hypothalamic involvement in proceptive presenting and allogrooming. The present findings indicate that the VMH and MPOA are involved, in different manner, in presenting of the female monkey, and that the LPOA, LHA and DMH regulate allogrooming. Thus, representations of these two behaviors are separeated in the hypothalamus of the female monkey.