ROLES OF MONOAMINES ON CENTRAL REGULATION OF THE PITUITARY LUTEOTROPHIC COMPLEX IN THE GOLDEN HAMSTER

PUTTIPONGSE VARAVUDHI

Summary: It is possible to suppress endogenous release of FSH component of the pituitary luteotrophic complex required for progesterone secretion and blastocyst implantation in the post coitus golden hamster by daily injection of 10-15 mg/kg of reserpine. Apparently, secretion of prolactin of these reserpinized animals was not disturbed since nidation could be stimulated by supplement treatment with daily 20 g FSH. Melatonin and inhibitor of brain monoamine oxidase, Marsilid at 4 mg/day and Marplan at 1 mg/day, are capable of reversing reserpine effect and induce normal nidation very similar to the effect of FSH. Melatonin could stimulate nidation in 15 mg/kg/day reserpinized animals at the dose as small as 100 mg/day but other monoamines and precursors are relatively ineffective even at far higher dose.

Both melatonin at 3x6 g/day and its related alkylamine serotonin at 3x 12 g/day could improve the incidence of blastocyst implantation in reserpinized animals by direct application into the lateral ventricle of the brain. No such effect is observed with 3x10 g/day of noradrenaline. These data favor the possible participation of the pineal hormone and possibly other related alkylamines including serotogenic neurohumor in central regulation of the release of pituitary FSH component of the luteotrophic complex at least during the progestational stage of pregnancy.

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Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok.

Received 23 February 1975