Gastric Effects of Galanin and Its Interaction with Leptin on Brainstem Neuronal Activity

Galanin is a 29-amino acid peptide that is widely distributed throughout the central nervous system, peripheral nervous sys-tem, and gastrointestinal and genitourinary tracts. Leptin is a hormone secreted from adipose tissue and the gut and other tissues. In this study, using an in vitro neonatal rat preparation, we investigated the gastric effects of galanin and its interaction with leptin on nucleus tractus solitarius (NTS) neurons receiving gastric vagal inputs. We showed that peripheral gastric galanin (300 nM) produced a mean inhibition response of 53.2 2.1% compared with the control level of 100 % (P 0.01) in 27 of 58 neurons tested. A concentration-dependent effect of galanin on NTS neuronal activity was observed. The galanin receptor an-tagonist [galanin-(1–12)-Pro3-(Ala-Leu)2-Ala amide], or M40, significantly reversed the galanin-induced inhibition effect (