Aim: Cerebellin1 (Cbln1) is highly expressed in the hypothalamus, a region of the brain involved in appetite regulation. However, the effects of Cbn1 on food intake are not known. The present study aimed to investigate the effect of Cbln1 on appetite regulation in rats. Methods: We determined the effect of (i) intracerebroventricular (ICV) injection of Cbln1 on food intake, behaviour and plasma pituitary hormone levels in male Wistar rats; (ii) Cbln1 on the release of hypothalamic neuropeptides known to modulate food intake from hypothalamic explants and (iii) fasting on hypothalamic Cbln1 mRNA expression. Results: (i) ICV administration of Cbln1 significantly increased food intake in rats and caused no adverse behaviours. ICV administration of Cbln1 significantly reduced plasma thyroid stimulating hormone (TSH) levels 10 min postinjection in rats. (ii) Cbln1 significantly increased the release of neuropeptide Y (NPY) from hypothalamic explants. (iii) Cbln1 mRNA expression levels were increased in the ventromedial nucleus of the hypothalamus in fasted rats. Conclusions: These data suggest that Cbln1 is a novel orexigenic peptide, which may mediate its effects via hypothalamic NPY.

Background: The thyroid hormone derivative 3‐iodothyronamine (T1AM), an endogenous biogenic amine, is a potent agonist of the G protein–coupled trace amine‐associated receptor 1 (TAAR1). T1AM is present in rat brain, and TAAR1 is expressed in hypothalamic nuclei associated with the regulation of energy homeostasis.Aim: The aim of this study was to determine the effects of T1AM on food intake in rodents.Methods: We determined the effect of (i) intraperitoneal (i.p.) administration of T1AM on food intake, oxygen consumption (VO2) and locomotor activity in mice; (ii) intracerebroventricular (ICV) injection of T1AM on food intake in male rats; (iii) c‐fos expression following ventricular administration of T1AM in male rats; and (iv) direct injection of T1AM into the arcuate nucleus (ARC) of male rats on food intake.Results: (i) T1AM (4 nmol/kg) significantly increased food intake following i.p. injection in mice but had no effect on VO2 or locomotor activity. (ii) ICV administration of T1AM (1.2 nmol/kg) significantly increased food intake in male rats. (iii) Intraventricular administration of T1AM significantly increased c‐fos expression in the ARC of male rats. (iv) Direct administration of T1AM (0.12, 0.4 and 1.2 nmol/kg) into the ARC of male rats significantly increased food intake.Conclusion: These data suggest that T1AM is an orexigenic factor that may act through the ARC to increase food intake in rodents.