Coexpression of MT₁ and RORα₁ melatonin receptors in the Syrian hamster Harderian gland

Abstract

Melatonin acts through several specific receptors, including membrane receptors (MT(1) and MT(2)) and members of the RZR/ROR nuclear receptors family, which have been identified in a large variety of mammalian and nonmammalian cells types. Both membrane and nuclear melatonin receptors have been partially characterized in Harderian gland of the Syrian hamster. Nevertheless, the identities of these receptors were unknown until this study, where the coexistence of MT(1) and RORalpha(1) in this gland was determined by nested RT-PCR followed by amplicon sequencing and Western-blot. Furthermore, the cellular localization of both receptors was determined by immunohistochemistry. Thus, MT(1) receptor was localized exclusively at the basal side of the cell acini, supporting the hypothesis that this receptor is activated by the pineal-synthesized melatonin. On the contrary, although a RORalpha(1)-immunoreactivity was observed in nuclei of epithelial cells of both sexes, an extranuclear specific staining, which was more frequently among those cells of males, was also seen. The implication of this possible nuclear exclusion of RORalpha(1) on the role of this indoleamine against oxidative stress is discussed.

Seasonal variations of melatonin in ram seminal plasma are correlated to those of testosterone and antioxidant enzymes

“…Although melatonin receptors have been evidenced in human and rat prostate benign tumours [50,51], there are no reports of melatonin receptors in prostate of healthy males, which might mediate the prostatic production of antioxidant enzymes. However, the lipophilic nature of melatonin would allow this hormone to cross the plasma membranes, and thus its possible stimulatory effect on antioxidant enzyme production could be mediated by nuclear or cytosol binding sites [52]. Furthermore, melatonin is supposed to regulate antioxidant enzyme activity via melatonin plasma membrane receptors MT 1 /MT 2 [23], increasing messenger RNA and protein levels of these enzymes [22].…”

IMPORTANCE OF LIGHT IN TEMPORAL ORGANIZATION OF PHOTORECEPTOR PROTEINS AND MELATONIN-PRODUCING SYSTEM IN THE PINEAL OF CARPCATLA CATLA

“…An additional band in the region of 65kDa in the carp pineal, however, appears to be unique. Though the molecular characterization of this protein requires further study, it is possible that this is the glycosylated form of the low molecular weight protein (Tomas-Zapico et al, 2005).…”

Melatonin and human skin aging

“…Currently, there are some proposals that melatonin-mediated expression of antioxidant enzymes is dependent of signal transduction pathways related to membrane, cytosolic and nuclear receptors, 53 but this hypothesis still needs to be elucidated.…”