Endocrine Effects of Pineal Gland and of Melatonin

  title={Endocrine Effects of Pineal Gland and of Melatonin},
  author={Marcella Motta and Franco Fraschini and Luciano Martini},
  journal={Proceedings of the Society for Experimental Biology and Medicine},
  pages={431 - 435}
Summary 1. Pinealectomy when performed in male rats results in a significant increase in weight of the testes, the prostates and the seminal vesicles. This suggests that the pineal gland usually inhibits the secretion of LH and of FSH. 2. Melatonin administered to male rats diminishes the weights of prostates and of seminal vesicles, but does not change testicular weight, indicating that exogenous melatonin suppresses the secretion of LH, but does not interfere with FSH release. 3. In… Expand
Role of the pineal gland in the control of gonadotropins and androgen-reducing enzymes in the rat.
It is hypothesized that the antigonadotropic activity of melatonin and its antiandrogenic effect might be exerted either via an interference on specific testosterone receptors, or through an influence on the activity of the α-reductase. Expand
Effects of melatonin administration on the reproductive system of the male rat.
Results on sex behavior show that none of theMelatonin treatments had significant effects on the parameters measured, that is, the frequencies of mounting, intromissions, and ejaculations were very similar in the control and the melatonin-treated groups. Expand
Increase in pituitary levels of luteinizing hormone and follicle-stimulating hormone after pinealectomy in both intact and castrated male rats.
The pituitary content and concentration of LH and the content of FSH were increased by pinealectomy in both intact and castrated rats, which may suggest that the pineal gland exerts an inhibitory action on the hypothalamic-pituitary axis that seems to be independent of the testicular function. Expand
Differential effects of melatonin on the testes of photoperiodic and nonphotoperiodic rodents.
It is suggested that melatonin, and by implication the pineal gland, may play a more importent role in regulating testicular function of rodents whose reproductive activity is markedly dependent upon seasonal changes in day length than of rodent whose reproductive performance is relatively insensitive to photoperiodic cues. Expand
The effect of the pineal gland on ovulation and pregnancy in the rat.
It appears, therefore, that under “normal” laboratory conditions the role that the pineal gland plays in ovulation and pregnancy is minimal at best. Expand
Brain Receptors Sensitive to Indole Compounds: Function in Control of Luteinizing Hormone Secretion
The placement of melatonin and of 5-hydroxytryptophol in the median eminence of castrated male rats is followed 5 days later by a significant decrease in pituitary stores of luteinizing hormone.Expand
Possible prolactin-mediated effects of melatonin on gonadotropin secretion in the rat
The existence of sex-dependent effects of melatonin on LH and FSH secretions is suggested and may be mediated by the different plasma prolactin levels in pituitary-grafted and sham-operated rats. Expand
Effect of Pineal Extracts and Hypothalamic Lesions on the Gonads of the Golden Hamster.
Implants of pineal powder or exogenous melatonin in the quantities employed did not significantly affect the weights of the testes, male accessory sex organs studied, or the uteri of females or their estrous cycles, unlike those in rats. Expand
Influence of exogenous melatonin on melatonin secretion and the neuroendocrine reproductive axis of intact male rats during sexual maturation.
It is demonstrated that exogenous melatonin can inhibit or delay sexual maturation in the male rat if administered between 20 and 40 days of age and suggested that this inhibitory action is exerted at the hypothalamic and/or pituitary level. Expand
Role of indoleamines and catecholamines in the control of gonadotrophin and growth hormone secretion.
This chapter investigates two hypotheses: that the administration of indoleamines, through the consequent inhibition of gonatrophins (GTH) could modify two GTH-dependent phenomena: puberty and ovulation and that the secretion of GH could also be under the antagonistic influence of catecholaminergic and indoleaminergic nervous pathways. Expand