Central and peripheral expression sites of phoenixin-14 immunoreactivity in rats

Phoenixin is a pleiotropic peptide involved in reproduction, anxiety and recently also implicated in the control of food intake. Besides the 20-amino acid phoenixin, the 14-amino acid phoenixin-14 also shows bioactive properties. However, the expression sites of phoenixin-14 in the brain and peripheral tissues are not yet described in detail. Therefore, a mapping of the brain and peripheral tissues from male and female Sprague-Dawley rats with a specific phoenixin-14 antibody was performed using western blot and immunohistochemistry. High density of phoenixin-14 immunoreactivity was detected in the medial division of the brain central amygdaloid nucleus, in the spinal trigeminal tract and in the spinocerebellar tract as well as in cells between the crypts of duodenum, jejunum and ileum. Medium density immunoreactivity was observed in the bed nucleus of the stria terminalis, in the area postrema, the nucleus of the solitary tract and the dorsal motor nucleus of the vagus nerve as well as in the peripheral parts of the islets of Langerhans in the pancreas. A low density of phoenixin-14 immunoreactivity was detected in the arcuate nucleus, the supraoptic nucleus and the raphe pallidus. After pre-absorption of the antibody with phoenixin-14 peptide, no immunosignals were observed indicating specificity of the antibody. Taken together, the widespread distribution of phoenixin-14 immunoreactivity gives additional rise to the pleiotropic functions of the peptide such as possible effects in gastrointestinal motility, immune functions and glucose homeostasis.