Plasma oxytocin concentration in virgin rats injected with CCK (20 μg/kg, i.v.) and hypertonic saline (4 ml/kg 1.5m NaCl, i.p.) after pretreatment with l-NAME (A) or l-NNA (B), or vehicle controls. Note thatl-NAME and l-NNA significantly enhanced oxytocin secretion evoked in response to hypertonic saline but not secretion evoked by CCK. Data are means ± SEM;n = 6–8 rats per group; *p < 0.05 compared with basal; #p < 0.05 compared with controls.