Immunocytochemical localization of melatonin in the harderian gland of Syrian hamster

Abstract

Background The Harderian gland (HG) is a tubulo‐alveolar gland found within the ocular orbit of animals which present a nictitating membrane. The Harderian gland is regarded as an extrapineal melatonin producing organ and both, photoperiod and melatonin have been shown to exert an important role in the metabolism and morphological features of such a gland. Our results seem to support the presence of melatonin in the nuclei of the HG cells, although our studies have not definitively proved such presence. Methods An Immunocytochemical anti‐melatonin technique was done over free sections of Bouin fixed material obtained from Syrian hamsters. Some of the sections were embedded in an epoxy resin and studied under electron microscope. Results The presence of positive immunoreaction was observed at the level of the nuclear membranes and in close relation to chromatin. No differences were observed between males and females nor between pinealectomized animals and control ones. Conclusions Our results suggest the binding of melatonin to the cell nucleus in all cell types of the gland. These observations are in accord with the binding studies performed by Acuña‐Castroviejo in purified cell nuclei of rat liver (Acuña‐Castroviejo et al., 1994. J. Pineal Res., 16:100–112) and the earlier one by Menéndez‐Peláez et al. (1993a,b, J. Pineal Res., 15:59–69; J. Cell Biochem., 53:373–382) using the light microscope. Our results seem to support the idea of a nuclear action of melatonin and they agree with the observations of Carlberg and Wiesenberg (1995, J. Pineal Res., 18:171–178) about the activation of some orphan receptors by melatonin. © 1996 Wiley‐Liss, Inc.

Characterization of melatonin high‐affinity binding sites in purified cell nuclei of the hamster (Mesocricetus auratus) harderian gland

“…The kinetic values for 125 I‐melatonin binding determined in this study are consistent with previous immunocytochemical studies by light [27, 28] and electron [21] microscopy suggesting the existence of a nuclear receptor for melatonin. Moreover, the data of this study agree with previous findings demonstrating the nuclear localization of melatonin in several tissues including harderian glands.…”

“…Whether these effects of melatonin (calendar information and/or antioxidant role) occur into the harderian glands directly or indirectly through other factors is yet unknown. Although melatonin is a small, highly lipophilic molecule that easily passes through biological membranes, data on its subcellular distribution and nuclear binding sites of melatonin in harderian glands are scarce [21]. Some studies show melatonin binding to crude membrane preparations from harderian glands of Syrian hamsters [22, 23] but none of them satisfied the pharmacokinetic properties of high affinity receptors.…”

Evidence of melatonin synthesis in the ram reproductive tract

“…The nuclear location of ASMT in spermatocytes, detected by immunohistochemistry in this study, was corroborated by the analysis of the sheep ASMT sequence (cNLS Mapper, (Kosugi et al, 2009b)), which predicted a bipartite nuclear localization signal within the terminal 60amino-acid region compatible to both nuclear and cytoplasmic location of the protein (Kosugi et al, 2008(Kosugi et al, , 2009a. Melatonin has also been previously identified in the nucleus of the harderian gland of Syrian hamster (Coto-Montes et al, 1996). Therefore, the melatonin produced by the ASMT located in the nuclei of spermatocytes may protect the DNA from apoptosis and ROS damage during meiotic divisions.…”

Immunohistochemical evidence for the presence of tryptophan hydroxylase and serotonin in the rodent Harderian gland

“…By analogy, a similar hypothesis can be proposed for the intracellular sites of 5-HT/melatonin synthesis in the Harderian gland, since lipid vacuoles, smooth endoplasmic reticulum and mitochondria are well represented in the type I cells of the gland. Recently, Coto-Montes et al (1996) have shown, using the ABC method, that immunoreactive melatonin is present in all cell types of the male Syrian hamster Harderian gland. This suggests that melatonin produced by type I cells probably acts on type II cells (paracrine effect of melatonin).…”

“…Although previous immunohistochemical studies have shown the presence of melatonin in the rodent Harderian gland (Bubenik et al 1976a(Bubenik et al , b, 1978Vivien-Roels et al 1981;Coto-Montes et al 1996), the cell type in which indoleamine synthesis occurs remains unknown. The purpose of the present study has therefore been to determine the presence and localization of cells immunoreactive for serotonin (5-HT; a melatonin precursor) and/or tryptophan hydroxylase (TPH; the rate-limiting enzyme for 5-HT synthesis) in male Wistar rats, Syrian hamsters and Djungarian hamsters.…”