Selective central activation of somatostatin receptor 2 increases food intake,grooming behavior and rectal temperature in rats

The consequences of selective activation of brain somatostatin receptor-2 (sst2) were assessed using the sst2 agonist,des- aa1,4-6,11-13-[dphe2,aph7(cbm),dtrp8]-cbm-sst-thr-nh2. food intake (fi) was monitored in ad libitum fed rats chronically implanted with an intracerebroventricular (i.c.v.) cannula. the sst2 agonist injected i.c.v. at 0.1 and 1 μg/rat dose-dependently increased light phase fi from 2 to 6 hours post injection (2.3±0.5 and 7.5±1.2 respectively vs. vehicle: 0.2±0.2 g/300 g bw,p<0.001). peptide action was reversed by i.c.v. injection of the sst2 antagonist,des-aa1,4-6,11-13- [pno2-phe2,dcys3,tyr7,daph(cbm)8]-sst-2nal-nh2 and not reproduced by intraperitoneal injection (30 μg/rat). the sst2 antagonist alone i.c.v. significantly decreased the cumulative 14-hours dark phase fi by 29.5%. other behaviors,namely grooming,drinking and locomotor activity were also increased by the sst2 agonist (1 μg/rat,i.c.v.) as monitored during the 2nd hour post injection while gastric emptying of solid food was unaltered. rectal temperature rose 1 hour after the sst2 agonist (1 μg/rat,i.c.v.) with a maximal response maintained from 1 to 4 hours post injection. these data show that selective activation of the brain sst2 receptor induces a feeding response in the light phase not associated with changes in gastric emptying. the food intake reduction following sst2 receptor blockade suggests a role of this receptor in the orexigenic drive during the dark phase.