Neural mechanism involved in the chronobiological activity of melatonin.

CARDINALI, DP; ROSENSTEIN, RE.; KANTEREWICSZ, BI; CUTRERA, R; FAILLACE, MP; DELLA MAGGIORE, VM; YANIELLI, PC

NEUROENDOCRINOLOGY LETTERS

The Pineal Gland, Brain Research Promotion

Lugar: London; Año: 1995 vol. 17 p. 103 - 114

0172-780X

Our perception of the function of the pineal gland and its hormone melatonin has attained a new dimension during the last decade. Through melatonin, the pineal is the principal organ present in vertebrates involved in the control of rhythmic adaptations to daily and seasonal cycles. Melatonin secretion occurs throughout the life, and is regulated not only by sympathetic nerve fibers but by other central pinealopetal projections also. Many neurotransmitter and neuromodulator receptor sites have been described in the pineal gland. The shape of the nocturnal melatonin signal is determined by the interactions of the afferent neural control and biochemical processes intrinsic to the pinealocytes. Modulation by hormonal signals also occurs (Reiter, 1991; Cardinali, 1995). Melatonin plays an established role in controlling reproduction and is involved in sexual maturation. It has a major influence on the circadian organization of vertebrates including human beings (Armstrong, 1991). The feasible nature of the effects of the melatonin signal on the circadian system is to influence the entrainment pathways of the oscillator. In the fetus, strong evidence exists for a physiological role of the maternal melatonin signal as an internal synchronizer (?zeitgeber?). The two central effects of melatonin, photoperiodic time measurement and circadian entrainment, are probably mediated through separate mechanisms. We will review data suggesting that γ-aminobutiric acid (GABA)-containing neurons play a significant role in melatonin-induced chronobiologicaal phenomena.