No abstract

1 The eects of GR205171, a selective tachykinin NK 1 receptor antagonist, were investigated on both the acute and delayed phases of cisplatin-induced nausea-like behaviour and vomiting in the conscious piglet. ) every 6 h throughout the experiment. 3 The latencies of the ®rst emetic episode (EE) and nausea-like behavioural episode (NE) increased in all experimental groups treated at T0 715 min , and the total number of both EE and NE during the 60 h was reduced in a dose-dependent manner. In piglets treated at T0 715 min with GR205171 1 mg kg 71 , eight out of 13 (62%) did not vomit throughout the experiment. Animals treated with GR205171 (1 mg kg 71) at T16 715 min exhibited an acute response to cisplatin but did not vomit during the delayed phase. The greatest inhibition of both nausea-like behaviour and vomiting was observed in piglets receiving multiple injections of GR205171. 4 These results demonstrate the long-lasting anti-emetic eects of GR205171, and con®rm the key role of substance P within the emetic re¯ex.

We determined the pharmacological and the antiemetic properties of SR 49059, a selective nonpeptide V(1a) receptor antagonist, on cisplatin-induced emesis in the piglet. Firstly, we clearly demonstrate that SR 49059 is a potent V(1a) receptor antagonist in vitro and in vivo in the piglet. In binding studies, [3H]-SR 49059 exhibited high affinity for V(1a) receptors in piglet liver membranes (K(d) of 0.76 +/- 0.12 nM and B(max) of 138 +/- 22 fmol/mg prot.). In vivo, in decerebrate piglets, SR 49059 (1 mg/kg iv) antagonized AVP (500 ng/kg iv)-induced hypertension for at least 150 min and also blocked, for at least 270 min at 3 mg/kg iv, the pressor responses to exogenous LVP. After single and repeated iv or icv administration, we studied the antiemetic properties of SR 49059 on cisplatin-induced emesis in piglets. Animals receiving an emetic dose of cisplatin (5.5 mg/kg, iv) were observed continuously for 60 h. Piglets acting as controls were iv administered with vehicle 15 min prior to cisplatin infusion (T0(-15min)), while experimental animals received a single iv administration of SR 49059 at the dose of 1 or 3 mg/kg. In additional piglets, we administered SR 49059 (3 mg/kg) every 12 h from T0(-15min) to T48(-15min) (cumulative dose, 15 mg/kg). Another set of animals - observed only during the acute phase - was administered with SR 49059 (10 mg/kg) every 3 h from T0(-15min) to T15(-15min) (cumulative dose, 60 mg/kg). Lastly, 10 piglets were given a bilateral icv injection of SR 49059 (500 microg and 1500 microg/side) 1 h prior to cisplatin infusion. In all groups treated with SR 49059, the latency of the first emetic episode and the incidence of vomiting during the acute, the delayed and the cumulative phases remained statistically similar to that observed in controls, suggesting that V(1a) receptors are not involved in the onset and completion of nausea and vomiting.