The facilitatory effect of N-methyl-D-aspartate on sexual receptivity in female rats through GnRH release.
The purpose of this study was to examine whether N-methyl-D-aspartate affects the sexual receptivity of female rats. Monosodium L-glutamate was used as a neurotoxin to induce hypogonadal status. Matured normal and monosodium L-glutamate-treated rats were ovariectomized and implanted subcutaneously with estradiol capsules. One week later, lordosis responsiveness was observed before and 10 min after N-methyl-D-aspartate (40 mg/kg of BW, ip) administration. The results showed that N-methyl-D-aspartate caused a remarkable increase of lordosis quotient in control rats but not in monosodium L-glutamate-treated rats. Moreover, the possible action site of N-methyl-D-aspartate in the enhancement of receptivity was evaluated by the post-castrational LH rise, pituitary LH release in response to GnRH, and N-methyl-D-aspartate-evoked GnRH releasability. The results revealed that: (a) serum levels of LH in monosodium L-glutamate-treated rats were lower (p < 0.01) than those of control rats after ovariectomy; (b) there was no significant difference of pituitary LH release responsiveness to GnRH test between two groups; and (c) N-methyl-D-aspartate-evoked LH release in monosodium L-glutamate-treated rats was similar to that in the control rats. In conclusion, N-methyl-D-aspartate may facilitate the sexual receptivity through stimulating GnRH release. The failure of N-methyl-D-aspartate in enhancing receptivity in monosodium L-glutamate-treated rats is probably due to the cellular damage by monosodium L-glutamate on specific areas responsible for lordosis.
Department of Physiology, Kaohsiung Medical College, Taiwan, ROC.
C
C
Hsu
J N
JN
Lee
M L
ML
Ho
B H
BH
Cheng
P H
PH
Li
J Y
JY
Yu
D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis*; D007006:Hypogonadism / Q000097:blood / Q000139:chemically induced; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism; D016202:N-Methylaspartate / Q000494:pharmacology*; D010052:Ovariectomy; D010902:Pituitary Gland / Q000378:metabolism; D011187:Posture; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D012970:Sodium Glutamate
D007987:Gonadotropin-Releasing Hormone; D016202:N-Methylaspartate; D007986:Luteinizing Hormone; D012970:Sodium Glutamate