Alarin is a member of the
galanin family of
neuropeptides that includes
galanin and
galanin-like peptide (GALP).
Alarin is an alternate transcript of the GALP gene and is expressed in the brain and periphery. Recently, it was shown in male rats that
alarin is an orexigenic
peptide that also regulates reproductive
hormone secretion. We hypothesized that
alarin would also have similar central effects on feeding and
luteinizing hormone (LH) secretion in mice as observed in rats. To test this hypothesis, we treated male mice with
alarin intracerebroventricularly (i.c.v.) and measured its effects on food intake,
body weight, body temperature, LH secretion, and Fos induction. We observed that i.c.v. injection of 1.0 nmol
alarin significantly increased immediate food intake (p<0.01) from 30 to 120 min post-injection and relative
body weight (p<0.05) after 24 h.
Alarin had no effect on body temperature compared to controls.
Alarin increased LH levels in male mice, an effect that was dependent on
gonadotropin-Releasing-Hormone (
GnRH) signaling. Furthermore,
alarin-stimulated Fos immunoreactivity was observed in diencephalic nuclei, including the hypothalamic dorsomedial nucleus and the bed nucleus of the stria terminalis. Our studies demonstrated that
alarin, like other members of the
galanin peptide family, is a neuromediator of food intake and reproductive
hormone secretion in male mice.