AG774 Sigma-AldrichOrexin-A, control peptide for AB3098

The hypothalamic peptides orexin A (OXA) and orexin B (OXB), deriving from the proteolytic cleavage of the precursor molecule prepro-orexin, have also been localized in multiple cerebral areas and peripheral organs. They regulate food intake, arterial blood pressure, heart rate, sleep/wake cycle, sexual behavior, arousal, and the hypothalamic/hypophyseal axes. Prepro-orexin mRNA expression and OXA-immunoreactivity were previously detected in the rat testis at different ages of postnatal development, with strong peptide signal in Leydig cells and spermatocytes. In this study, OXA-immunoreactivity was found in Sertoli cells and spermatids of rat testis. Hematoxylin-counterstained sections revealed OXA positive spermatids in the stages of the germinal epithelium cycle ranging from the VIIth to the XIVth. The expression of prepro-orexin mRNA and of the protein in the testis tissue was ascertained by reverse-transcription polymerase chain reaction and Western blotting analysis, respectively. Although the functional role of OXA in the male genital tract still remains to be elucidated, our findings provide the first evidence that Sertoli cells, belonging to the tubular compartment of testis, represent an important source of OXA, thus suggesting the potential involvement of the peptide in the control of seminiferous epithelium development.

The hypothalamic peptide orexin A (oxA) binds specifically the G-protein-coupled orexin receptor 1 (ox1R). It is involved in many physiological functions including the regulation of food intake, sleep-wake cycle, arterial blood pressure, heart rate, and sexual behavior. The localization of oxA in adrenal glands, stomach, bowel, pancreas, and testis has recently been assessed. Here, we provide the first evidence for the expression of oxA and ox1R in the vestibular glands of mammalian genital tract.

The hypothalamic peptide orexin A (oxA) derives from the proteolytic cleavage of the precursor molecule prepro-orexin. It binds with the high affinity G-protein-coupled orexin receptor 1 (OX1R). Here, we report the detection of oxA and OX1R in the principal cells of the rat caudal epididymis by immunohistochemistry. Both oxA and OX1R immunolabelling showed cytoplasmic supranuclear localization, filling the apical portion of the cells. The expression of prepro-orexin and OX1R mRNA transcripts in the rat epididymis was assessed by reverse-transcriptase polymerase chain reaction, while the presence of both these proteins in the tissue was confirmed by Western blotting analysis. Our findings provide the evidence for the presence of oxA and OX1R in the rat epididymis, and demonstrate that both proteins are locally synthesised, thus suggesting a role for oxA in governing the fertilizing capability of the immature male gamete.

Orexin A (oxA) and orexin B are recently discovered peptides derived from the proteolytic cleavage of the common precursor prepro-orexin. They bind two G protein-coupled receptors, defined orexin 1 (ox1R) and orexin 2 receptor. Both peptides are highly expressed in the lateral hypothalamic area of the brain and are involved in the regulation of many functions of the body, the best investigated of which is food intake. Recent data described the presence of orexins in peripheral organs such as the adrenal glands, stomach, bowel, pancreas, and testis. Here, we report the detection of oxA and ox1R in the exocrine and endocrine cytotypes of the cattle urethroprostatic complex by using immunohistochemistry. The expression of prepro-orexin and ox1R mRNA transcripts in the prostatic tissue was assessed by reverse-transcriptase polymerase chain reaction, while the presence of both the proteins in the tissue was confirmed by Western blotting analysis. Our findings provide the first evidence for the presence of oxA and ox1R in the urethroprostatic complex of the cattle and demonstrate that both proteins are locally synthesized, thus suggesting a role for oxA on both physiological and pathological functioning of the complex.

The hypothalamus plays a central role in the integrated control of feeding and energy homeostasis. We have identified two novel neuropeptides, both derived from the same precursor by proteolytic processing, that bind and activate two closely related (previously) orphan G protein-coupled receptors. These peptides, termed orexin-A and -B, have no significant structural similarities to known families of regulatory peptides. prepro-orexin mRNA and immunoreactive orexin-A are localized in neurons within and around the lateral and posterior hypothalamus in the adult rat brain. When administered centrally to rats, these peptides stimulate food consumption. prepro-orexin mRNA level is up-regulated upon fasting, suggesting a physiological role for the peptides as mediators in the central feedback mechanism that regulates feeding behavior.