Vipergic innervation of the mammalian pineal gland

Abstract

The present article reviews the literature relative to VIP- and PHI-containing nerve fibers in the pineal gland of mammals. The article summarizes data on the presence and distribution of the two peptides in the brain of mammals, their role in neuronal metabolism, and the significance and origin of VIPergic and PHIergic cerebrovascular nerve fibers. Special emphasis is placed on VIP- and PHI-containing nerves in the pineal gland. The morphology of the fibers, the nature of the innervation, and the distribution of immunoreactive nerves within the pineal gland are examined. The review discusses the nature of the classical and "central" innervation of the pineal gland. The possible site of origin of pinealopetal VIPergic and PHIergic fibers is investigated, with special reference to ganglia of the head, and particularly to the pterygopalatine, otic, and trigeminal ganglia. The nature of VIP (and PHI) receptors is examined with reference to the most recent acquisitions in the field. Based on the data, a role for VIP (and PHI) in pineal metabolism is discussed.

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

“…The pineal gland of all mammalian species studied so far contains a VIPergic innervation (see Cozzi, 1999 for review). The species studied include rabbit, cat and pig (Uddman et al, 1980), rat (Mikkelsen et al, 1987), gerbil Shiotani et al, 1986), sheep (Cozzi et al, 1990), and mouse .…”

“…Shiotani et al (1986) have demonstrated, in the gerbil, that the VIP fibers originate from the parasympathetic pterygopalatine ganglia. In addition, some VIP fibers may originate from central structures that project to the pineal gland or from the trigeminal ganglia (in the sheep, Cozzi, 1999). VIPergic fibers of parasympathetic origin enter the pineal gland through the pial capsule, travel within the gland following the blood vessels, and end among clusters of pinealocytes; central VIPergic fibers enter via the deep pineal gland.…”