Light and electron microscopic immunocytochemical study on the innervation of the pineal gland of the tree shrew (Tupaia glis), with special reference to peptidergic synaptic junctions with pinealocytes

Central GABAergic innervation of the mammalian pineal gland: A light and electron microscopic immunocytochemical investigation in rodent and nonrodent species

“…Previous observations from our laboratory revealed that in the tree shrew abundant myelinated and unmyelinated fibers entered the pineal gland from the habenular and posterior commissures and that the fibers, which remained after superior cervical ganglionectomy, were mostly immunonegative for a number of peptides, TH, and ChAT (Kado et al, 1999). From the above data, the possibility that the central pinealopetal fibers of this animal are amino acidergic arose.…”

“…Light microscopic examinations of silverimpregnated or myelin sheath-stained sections and electron microscopic observations have shown that myelinated and unmyelinated fibers from the habenular and posterior commissures are found to enter the gland in various mammals (Vollrath, 1981;Møller, 1984, 1985). Recent immunohistochemical studies have suggested the existence of presumptive central pinealopetal fibers containing a variety of neuropeptides Møller, 1984, 1985;Møller et al, 1996), biogenic amines such as serotonin (Matsuura and Sano, 1983) and histamine , and neurotransmittersynthesizing enzymes including tyrosine hydroxylase (TH; Kado et al, 1999;Matsushima et al, 1999) and choline acetyltransferase (ChAT; Phansuwan-Pujito et al, 1999). Despite the considerable immunohistochemical data available, it has been impossible to identify putative neurotransmitter substances, which are commonly found in central pinealopetal fibers in many mammalian species.…”

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

“…An sPergic innervation was described in the pineal gland of the rat (Ronnekleiv and Kelly, 1984), gerbil (Shiotani et al, 1986), monkey (Ronnekleiv, 1988), cow , cotton rat (Matsushima et al, 1994), tree shrew (Kado et al, 1999), and pig (Przybylska-Gornowicz et al, 2000b). The sPergic innervation is dense, dispersed through the whole gland, and terminates in the perivascular space and between the pineal cells (see, for example, Ronnekleiv and Kelly, 1984).…”

“…The sPergic innervation is dense, dispersed through the whole gland, and terminates in the perivascular space and between the pineal cells (see, for example, Ronnekleiv and Kelly, 1984). The possibility that sPergic fibers originate from neurons of the habenular nuclei, at least in the rat and cow, rely on the following observations: 1) some sP-containing neurons of the habenular area project their axons via the habenular commissure toward the proximal part of the pineal gland (Ronnekleiv and Kelly, 1984;; 2) pineal sPergic innervation is not modified after SCGx (Ronnekleiv and Kelly, 1984;Matsuura et al, 1994;Kado et al, 1999); 3) a direct neural connection between the habenular nuclei and the pineal gland was demonstrated by lesion experiments (Ronnekleiv and Møller, 1979;Møller and Korf, 1983b), electrophysiology (Reuss et al, 1984), and tracing studies (Møller and Korf, 1983b). In addition, pineal sP is proposed to originate from the trigeminal ganglia (see Shiotani et al, 1986;Reuss et al, 1992a;Reuss, 1999 for review).…”

“…CGRP-containing fibers have been identified in the pineal gland of the gerbil (Shiotani et al, 1986), rat (Reuss et al, 1992a;Matsuura et al, 1994), cotton rat (Matsushima et al, 1994), and tree shrew (Kado et al, 1999). In the cotton rat, CGRP fibers arrive via the conarian nerve; they are largely spread out in the superficial pineal gland, being rare in the stalk and deep pineal gland, and absent in the habenular and posterior commissures (Matsushima et al, 1994).…”