Influence of pinealectomy on sexual behavior of normal and monosodium L-glutamate-treated rats.
Subcutaneous injections of monosodium L-glutamate (MSG) were administered, as a neurotoxin, at a dose of 4 mg/g body weight to rat pups on days 1 and 3 postnatally. Pinealectomy was performed at 6 weeks of age, and animals were allowed to mature. The intact MSG-treated rats showed a decrease of lordosis quotient in females and a reduction of ejaculation frequency and an increase in mount frequency in males. Pinealectomy caused no significant improvement on sexual behavior of the saline-treated normal rats, but it caused a marked improvement of the sexual receptivity in MSG-treated female rats and reinstated ejaculation in MSG-treated males. The circulatory sex steroid levels, estrogen in females and androgen in males, were not significantly different between the intact and pinealectomized MSG-treated groups in the respective sexes, whereas the progesterone level in females was significantly elevated in the pinealectomized MSG-treated group compared with the intact MSG-treated group. These findings suggest that the pineal gland plays an inhibitory role on the sexual behavior of MSG-treated rats and the improvement of sexual behavior following pinealectomy may be dependent on certain mechanisms other than the actions of circulatory androgens or estrogens.
Hsu
C
C
Department of Physiology, Kaohsiung Medical College, Taiwan, Republic of China.
Huang
H T
HT
Hsu
H K
HK
Yu
J Y
JY
Peng
M T
MT
D000704:Analysis of Variance; D000728:Androgens / Q000097:blood; D000818:Animals; D003307:Copulation / Q000187:drug effects / Q000502:physiology; D004542:Ejaculation / Q000187:drug effects / Q000502:physiology; D004967:Estrogens / Q000097:blood; D005260:Female; D005971:Glutamates / Q000494:pharmacology*; D008297:Male; D010870:Pineal Gland / Q000502:physiology* / Q000601:surgery; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D012970:Sodium Glutamate / Q000494:pharmacology*
D000728:Androgens; D004967:Estrogens; D005971:Glutamates; D011374:Progesterone; D012970:Sodium Glutamate