Spexin Expression in Normal Rat Tissues

Abstract

Spexin is a highly conserved peptide which was recently identified through the bioinformatics approach. Immunohistochemical analysis of its expression has not yet been performed. Thus, in this study, we examined spexin location in a wide range of rat organs by both RT-PCR and IHC. RT-PCR identified spexin mRNA in all tissues examined. Spexin immunoreaction was mainly cytoplasmic. Spexin was immunohistochemically detected, although with different staining intensities, in epithelia and glands of skin and respiratory, digestive, urinary, and reproductive systems. Smooth muscle cells showed weak immunostaining, and connective tissue was negative. In the central nervous system, neuronal groups showed different intensities for reaction product. Immunoreaction was also found in ganglionic cells of both trigeminal and superior cervical ganglia and in photoreceptor, inner nuclear, and ganglionic layers of the retina. In the endocrine system, spexin immunoreaction was detected in the hypothalamic paraventricular and supraoptic nuclei; adenohypophysis, thyroid, and parathyroid glands; adrenal cortex and medulla (mainly ganglionic cells); Leydig cells; and thecal, luteal, and interstitial cells of the ovary. Because of its widespread expression, spexin is probably involved in many different physiological functions; in particular, location of spexin in neurons and endocrine cells suggests its roles as neurotransmitter/neuromodulator and endocrine factor.

Goldfish spexin: solution structure and novel function as a satiety factor in feeding control

“…Consistent with the recent report on tissue expression profiling in the rat (25), SPX was found to be expressed ubiquitously in goldfish. The widespread pattern of SPX distribution is in agreement with the pleiotropic functions of SPX reported in different tissues in mammals.…”

“…Consistent with the high levels of transcript expression in different brain areas, protein expression of SPX was also confirmed by LC/MS-MS in protein pulldown prepared from goldfish brain lysate, using the antiserum for SPX mature peptide. In the rat, SPX transcripts and SPX protein expression could be located in brain areas, including the cerebral cortex, hypothalamus, cerebellum, and brain stem (25). Given that SPX immunoreactivity was also detected in the cytoplasm of neuronal cells in these brain areas, it is likely that SPX may function as a neurotransmitter/neuromodulator within the CNS.…”

“…By Northern blot and RT-PCR, SPX gene expression was confirmed in human and mouse, especially in the kidney, pancreas, brain, and placenta (19,34). The most extensive study on tissue expression profiling of SPX has been published recently in the rat using immunohistochemical staining (25). In this case, SPX was found to be expressed ubiquitously in body integument, nerve fibers/nuclei in the brain and periphery nervous structures, and major organs/tissues of the respiratory, digestive, urinary, and reproductive systems.…”

Decreased Spexin Levels in Patients with Type 1 and Type 2 Diabetes

“…Porzionato et al [1] showed the expression of spexin in various rat tissues such as the hypothalamus, pons, cerebral cortex, kidney, ovary, adrenal gland, thyroid, anterior pituitary, and stomach. The expression of spexin in endocrine cells suggested its possible role as an endocrine factor [1].…”

Escitalopram affects spexin expression in the rat hypothalamus, hippocampus and striatum

“…In the brain, many SPX immunopositive neural populations have been described, while neuroglia are usually negative, the highest reaction was detected in the hypothalamic paraventricular and supraoptic nuclei. Hippocampal neurons show moderate immunoreactivity as well as cerebellar Purkinje cells and brainstem neurons [6].…”