Figure 7. Effects of hepatic or subdiaphragmatic vagotomy on light-induced GVNA responses.

A, group data showing time course of the effects of melatonin (0.1 ng; filled circles) and vehicle (open circles) i.c.v. injections on light (2.1 × 10¹⁴ photons cm⁻² s⁻¹, 10 min)-induced decrease in GVNA in intact control, hepatic vagotomised and total subdiaphragmatic vagotomised mice. B, group data showing the effects of i.c.v. melatonin on peak responses of the GVNA to light, compared with those of i.c.v. vehicle, in intact control (n = 14), hepatic vagotomised (n = 7) and total subdiaphragmatic vagotomised (n = 7) animals. Melatonin (i.c.v.) significantly enhanced the light-induced decrease in GVNA. The i.c.v. melatonin-induced suppression of the GVNA was observed in all cases (P > 0.05, treatment effect, ANOVA) even after the total subdiaphragmatic vagotomy. *P < 0.05, vehicle vs. melatonin.