Presence of oxytocinergic neuronal-like cells in the bovine pineal gland: an immunocytochemical and in situ hybridization study (original) (raw)
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The chemical neuroanatomy of the mammalian pineal gland: Neuropeptides
Neurochemistry International, 1996
The mammalian pineal gland contains multiple afferent peptidergic nerve fibres. Sympathetic nerve fibres, with their origin in the superior cervical ganglia, contain neuropeptide Y colocalized with norepinephrine. Other pinealopetal nerve fibres, probably originating in the pterygopalatine ganglion, contain vasoactive intestinal peptide and peptide histidine isoleucine. Fibres containing substance P and calcitonin gene-related peptide have also been demonstrated in pinealopetal nerve fibres. These fibres might originate in the trigeminal ganglion. The neurotransmitter content of the fibres of the central innervation, innervating the gland from the brain via the pineal stalk, has not been elucidated. However, strong indications for the presence of neuropeptide Y, substance P, somatostatin, and vasopressin in these fibres have been presented. Recent immunohistochemical studies have further shown the presence of subtypes of pinealocytes containing neuropeptides. Thus, pinealocytes containing fl-endorphin, leu-enkephalin, and somatostatin have been demonstrated in the gland. Immunohistochemistry at the electron microscopical level has shown, that in some species, leu-enkephalin containing pinealocytes make synaptic contacts with other pinealocytes indicating of paracrine regulation of the pineal gland. It must however be emphasized that large interspecies variations exist with regard to the peptidergic pineal innervation and its content of peptidergic cells.
Cell & Tissue Research, 1993
In addition to the stimulating influence of the sympathetic system on the function of the mammalian pineal gland, neuropeptides such as neuropeptide Y, vasoactive intestinal polypeptide and arginine-vasopressin (AVP) are thought to function as modulators. Since AVP has been shown to influence pineal melatonin synthesis, the aim of the present study was to investigate the possible effects of the second hypothalamic nonapeptide oxytocin (OT), which likewise has been detected in the pineal gland. We therefore studied "synaptic" ribbon (SR) numbers, N-acetyltransferase (NAT) activity and the intracellular concentration of cyclic guanosine monophosphate (cGMP) following in vitro incubation of rat pineals in media containing OT (10 5 M), noradrenaline (NA, 10 .5 M) or both NA and OT. Pineal glands were derived from rats of three different strains (Sprague-Dawley, Long-Evans and the AVP-deficient strain Brattleboro). Neither morphological nor biochemical analyses showed a difference between control and OT-incubated organs in any of the strains tested. In Brattleboro rats, but not in the other strains, noradrenaline slightly increased the number of SR which was not observed when NA and OT were combined. The addition of NA resulted in distinct augmentation of NAT activity and cGMP content, which were not affected by additional OT application. These results suggest that oxytocin is not crucially involved in the regulation of pineal gland function.
The anatomy and innervation of the mammalian pineal gland
Cell and Tissue Research, 2002
The parenchymal cells of the mammalian pineal gland are the hormone-producing pinealocytes and the interstitial cells. In addition, perivascular phagocytes are present. The phagocytes share antigenic properties with microglial and antigen-presenting cells. In certain species, the pineal gland also contains neurons and/or neuron-like peptidergic cells. The peptidergic cells might influence the pinealocyte by a paracrine secretion of the peptide. Nerve fibers innervating the mammalian pineal gland originate from perikarya located in the sympathetic superior cervical ganglion and the parasympathetic sphenopalatine and otic ganglia. The sympathetic nerve fibers contain norepinephrine and neuropeptide Y as neurotransmitters. The parasympathetic nerve fibers contain vasoactive intestinal peptide and peptide histidine isoleucine. Recently, neurons in the trigeminal ganglion, containing substance P, calcitonin gene-related peptide, and pituitary adenylate cyclaseactivating peptide, have been shown to project to the mammalian pineal gland. Finally, nerve fibers originating from perikarya located in the brain containing, for example, GABA, orexin, serotonin, histamine, oxytocin, and vasopressin innervate the pineal gland directly via the pineal stalk. Biochemical studies have demonstrated numerous receptors on the pinealocyte cell membrane, which are able to bind the neurotransmitters located in the pinealopetal nerve fibers. These findings indicate that the mammalian pinealocyte can be influenced by a plethora of neurotransmitters.
An immunohistochemical study of neuropeptide Y in the bovine pineal gland
Journal of Pineal Research, 1993
An immunohistochemical study of the bovine pineal gland was performed using rabbit polyclonal antibodies raised against neuropeptide Y (NPY) or against the C-terminal flanking peptide of proNPY (CPON). A large number of NPY/CPON-immunoreactive (IR) nerve fibers were demonstrated throughout bovine pineal gland. The IR-fibers were located in the capsule of the gland, usually piercing into the gland together with blood vessels. In the gland itself, the fibers were also located intraparenchymally between the pinealocytes. Within the rostral and caudal areas of the pineal stalk, NPY-IR fibers were also observed, and these fibers could be followed not only into the gland but also to the habenular and posterior commissures. The morphological localization of the NPY-IR nerve fibers in the bovine pineal gland indicate that the majority of fibers originate from the superior cervical ganglion. However, some fibers probably originate from the brain itself.
Anatomia Histologia Embryologia, 2007
The presence and co-localization of vasoactive intestinal polypeptide (VIP), peptide N-terminal histidine C-terminal isoleucine (PHI), pituitary adenylate cyclase-activating peptide (PACAP), somatostatin (SOM), calcitonin gene-related peptide (CGRP), substance P (SP) and the neuronal isoform of nitric oxide synthase (NOS) were studied in neuronal structures of the pig pineal gland. Paraformaldehyde-fixed pineals of 3-month-old gilts were sliced into serial cryostat sections, which were subjected to a set of double immunofluorescence stainings. Based on the co-existence patterns of neuropeptides, five populations of nerve fibres supplying the pig pineal were distinguished: (1) PHI-positive, (2) PACAP-positive, (3) SOM-positive, (4) SP/CGRP-positive and (5) SP-positive/CGRP-negative. Only a subpopulation of PHI-positive fibres contained VIP at the level detectable by immunofluorescence. NOS was found in some intrapineal PHI- and VIP-positive fibres. PHI-, VIP- and NOS-positive nerve fibres were more numerous in the peripheral than in the central part of the pineal. PACAP-positive fibres were equally distributed within the gland. The density of SOM-positive fibres was higher in the ventro-proximal than in the dorso-distal part of the pineal. SOM was also detected in some neuronal-like cells or specialized pinealocytes situated in the central region of the gland. Two populations of fibres containing SP were found: CGRP-positive, present in the distal and central parts of the pineal as well as CGRP-negative, localized in the proximal compartment of the gland.
Histology and histopathology, 2013
Innervation of the mammalian pineal gland during prenatal development is poorly recognized. Therefore, immunofluorescence studies of the pineals of 70- and 90-day-old foetuses of the domestic pig were performed using antibodies against tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DβH), neuropeptide Y (NPY) and C-terminal flanking peptide of NPY (CPON). The investigated glands were supplied by numerous nerve fibres containing TH and DβH. The density of these fibres was higher in the distal and middle parts of the gland than in the proximal one. NPY and CPON were identified in the majority of DβH-positive fibres as well as in a small population of DβH-negative fibres localized mainly in the proximal part of the pineal. The immunoreactive fibres were more numerous in 90-day-old foetuses than in 70-day-old ones. The effect of norepinephrine on melatonin secretion by the foetal pineals in the short-term organ culture was studied to determine the role of DβH-positive fibres during p...
Tachykinins and tachykinin-receptors in the rat pineal gland
European Journal of Neuroscience, 2005
High-pressure liquid chromatography of extracts of rat pineal glands, followed by radio immunological analysis with antibodies against tachykinins, demonstrated the presence of substance P, neurokinin A and neurokinin B in the superficial rat pineal gland. Immunohistochemistry on perfusion-fixed rat brain sections showed substance P and neurokinin A to be present in nerve fibers located both in the perivascular spaces as well as intraparenchymally between the pinealocytes. After extracting total RNA, followed by reverse transcription and polymerase chain reaction amplification with primers specific for NK 1-, NK 2-and NK 3-receptors, agarose gel analysis of the reaction products showed the presence of mRNA encoding all three neurokinin receptors. Immunohistochemical analysis showed NK 1 receptor to be located in the interstitial cells of the gland. This location was confirmed by use of in situ hybridization using radioactively labeled antisense oligonucleotide probes. Double immunohistochemical stainings showed that the NK 1-immunoreactive cells were not a part of the macrophages or antigen-presenting cells of the gland. Our study suggests that tachykinins, after release from intrapineal nerve fibers, are involved in an up to now unknown function, different from that of melatonin synthesis.
European Journal of Neuroscience, 2001
Hypocretin-1 (HCRT-1) and hypocretin 2 (HCRT-2), also known as orexin-A and orexin-B, are two neuropeptides derived from the same precursor. Hypocretinergic neurons have been found exclusively in the hypothalamic dorsolateral area. These neurons are implicated in sleep and feeding through activation of speci®c G-protein-coupled orexin-1 and orexin-2 receptor (OR-R1 and OR-R2). The purpose of this study was to determine the existence of the HCRT peptides in the central input of the rat pineal gland. Further, OR-R1 and OR-R2 expression was determined in the pineal gland and the effect of HCRT-2 on melatonin synthesis and secretion was analysed in dissociated rat pinealocytes. A large contingent of HCRT-positive nerve ®bres and terminals were observed in the epithalamus, many of which entered into the pineal parenchyma. A signi®cant number of nerve ®bres endowed with positive boutons were identi®ed in the pineal stalk, though the number of positive ®bres decreased along the extension of the stalk. So far, no positive ®bres have been found in the super®cial pineal gland. RT-PCR analysis revealed the expression of OR-R2 mRNA, whereas OR-R1-receptor mRNA was not detected. When tested alone, HCRT-2 had no effect on secretion of melatonin from cultured rat pinealocytes. However, HCRT-2 partially inhibited (by a maximum of 30%) the b-adrenergic-induced melatonin secretion. The same effect was seen on activation of N-acetyltransferase activity. The distribution and the large number of HCRT-positive ®bres together with the effect on noradrenaline-mediated melatonin release through speci®c receptors suggests that these peptides may be signi®cant central transmitters in pineal function, probably mediating homeostatic signals to the pineal gland.