Pd 176252

To block GRP receptors, we used the potent BB2 receptor antagonist RC-3095 (Sigma-Aldrich, 0.9 mM in sterile 0.9% saline) or the non-peptidergic BB2 antagonist PD176252 (Tocris, 0.342 mM in 50% dimethyl sulfoxide (DMSO)). To block VIP receptors, we used the VIP antagonist [D-p-Cl-Phe6, Leu17]-VIP (Tocris, 1 mM in sterile 0.9% saline) or the potent VPAC2 antagonists PG99-465 (Bachem, 1 mM in 0.9% sterile saline). To test the antagonistic properties of RC-3095, we also used porcine GRP (Sigma-Aldrich, 0.3 mM in sterile 0.9% saline). Cocktails of RC-3095 + PG99-465 and of PD176252 + PG99-465 were prepared so that the molarity of each substance was identical when administered alone and in the cocktail. Molarity of antagonists were selected to be about 10x greater than the minimal molarity of GRP and VIP that yielded maximal phase shifts in previous studies (Piggins et al., 1995) . Injections occurred in DD with the aid of night-vision goggles (BG15Alista, Richmond Hill, Ontario, Canada). All manipulations occurred approximately 10 days prior to and following cage changes.