Prefeeding potentiates anorectic actions of neuromedin B and gastrin releasing peptide.

We report that the anorectic potency of neuromedin B (NMB) and gastrin-releasing peptide (GRP) is potentiated using a prefeed paradigm. During the light phase, adult male Sprague-Dawley rats (groups of n = 6) were given 30-min (pre-feed) access to a liquid diet. Thirty min later rats were injected i.p. with GRP or NMB (0, 8, 16, 32 or 64 micrograms kg-1) and given further access to the liquid diet. In prefed (PF) rats, high doses of NMB (32 and 64 micrograms kg-1) delayed the onset of eating in the test by > 10 min, significantly suppressing 30-min intake. The same doses of NMB in non prefed (NPF) rats were ineffective. Weak effects of GRP in NPF rats to reduce meal size were also enhanced under PF conditions. Exogenous GRP and NMB, in particular, appear to interact with processes stimulated by the postingestive actions of food, supporting a role for peripheral, endogenous GRP and NMB in the development of satiation and the maintenance of postprandial satiety, respectively.