Effects of propranolol on baclofen-induced hyperphagia in rats

We have previously demonstrated that both acute and chronic systemic administration of the GABAB receptor agonist baclofen (bac) increases food intake in non-deprived rats by a central mechanism of action (see Ebenezer et al., 1992; Patel et al., 2010). As part of a programme to investigate possible interactions of bac with central neurotransmitter/neuromodulator systems on ingestive behaviour, the present study was undertaken to examine the effects of the β-adrenoceptor antagonist propranolol (prop) on bac-induced hyperphagia. Male Wistar rats (n = 8; body weight – 375 – 455 g) were injected i.p. with either saline (sal) followed 5 min later by sal, sal followed by bac (2 mg kg-1), prop (5 mg kg-1) followed by sal, or prop (5 mg kg-1) followed by bac (2 mg kg-1). Immediately after the 2nd injection the rats were placed singly in separate experimental cages with free access to food and water. Cumulative food intake was measured as described previously (Ebenezer et al., 1992). A repeated measures design was used with each rat receiving all treatments. The data was analysed by ANOVA and post-hoc Tukey test. The results for cumulative food intake at 60 min are shown in Fig. 1. Bac significantly increased food intake (P