5-HT1A receptor antagonist WAY-100635 reduces the analgesic effect of taltirelin on thermal nociception. WAY-100635 (WAY) was administered either i.p. ((a); 0.3 and 1 mg kg−1) or i.t. ((b); 1, 3 and 10 μg) 15 min before the administration of taltirelin hydrate (tal, 1 mg kg−1, s.c. in (a) and 0.3 μg, i.c.v. in (b), administered at time zero). Each point represents the mean (±s.e.m.) result from six mice. Ordinates: mean normalized tail flick latencies (tail flick test; left) and nociceptive thresholds (tail pressure test; right). Abscissae: time in minutes after taltirelin application. The asterisks indicate data points for which a significant difference between the taltirelin-only and WAY-100635-treated groups was observed, as determined by two-tailed non-parametric Bonferroni-type multiple comparisons following the Kruskal–Wallis test (two comparisons in three groups in (a), and three comparisons in four groups in (b), *P<0.05).