ELECTRO-MYOGRAPHIC STUDY OF THE HUMAN ABDOMINAL MUSCLES AFFECTED BY SEXUAL HORMONES

Abstract

The action current of the abdominal muscles was studied with the technique of EMG, using diverse subjects-normal female and male adults, juveniles and castrated individuals. To supplement the observations, some animal experiments and the observation on the cases of Adison's disease were performed.
1. Normal female adults. They are the only subjects who show periodic changes in the discharge-occurring simultaneously with the menstruation cycle. The electrical discharges are very much weakened in a few day before and after the menstruation, or totally vanished during the menstruation proper. The active discharges in the mid menophase can very effectively be suppressed by progesterone, and less so by chorionic gonadotrophin. Following a pretreat ment with progesterone and the muscles made electrically silent, testosterone, estradiol or corticosterone brings about a new outburst of the electrical activity.
During the menstruation, the decreased or vanished discharges can be made active by estradiol or in lesser degree by the placental hormone, anterior pituitary hormone or chorionic gonadotrophin.
2. Prepuberal females. Juveniles, age over 7 years, show the inhibitory response to progesterone, but those age below 6 years indicate a faint response, if any.
3. Females in menopause. These show a distinct progesterone inhibition.
4. Totally oophorectomized females. No periodicity was detected. Progesterone inhibits effectively the discharges. Testosterone, estradiol, corticosterone, anterior pituitary or placental hormone revives the discharge which has been suppressed by progesterone.
5. Normal male adults. No periodicity was observed. Progesterone is nonreactive.
6. Juvenile males. Those age over 6 years can hardly respond to progesterone and those below show a faint response, if any.
7. Castrated males. No periodicity was observed. After the progesterone inhibition, testosterone, estradiol or anterior pituitary hormone brings back the electrical discharge.
Animal experiments. A large dose of progesterone given to the female or castrated male rabbit induces a decrease or totally suspension of the electrical discharge of the abdominal muscles. The male animal responses with much lesser degree.
A very large dose of progesterone administered to the female rat brings a quiet state or even stupor. The abdominal muscles decrease or loose the discharges faster than all the others.
Adison's disease. In severe cases, the disappeared electrical activity of the abdominal oblique muscles can be made active by the injection of estradiol or corticosterone.