Fig. 9.

Effects of orexin-A on food intake in rats pre-treated by injection of DSAP or SAP into the PVH. For feeding tests, orexin-A (0.5 nmol/rat) or saline (Sal) was injected into fourth ventricle (A) or lateral ventricle (B) in cannulated rats using the same protocol for both ventricular sites. Food intake measured during the 4 hours after the injection are shown. In A, N = 8 rats per group. *P < 0.01, vs. SAP Sal control. In B, N = 5 or 6 rats per group. *P < 0.05, vs. SAP Sal control. Retrograde lesion of hindbrain CA neurons by PVH DSAP injection was confirmed by testing feeding induced by 2DG (200 mg/kg, i.p.), which was significantly inhibited in DSAP rats (*P < 0.001, vs SAP rats), and by post mortem immunohistochemistry, which showed that hindbrain CA neurons, but not PeFLH orexin neurons, were lesioned by PVH DSAP injections (these data are not shown here). Loss of orexininduced feeding responses at both the 4V and the LV injection sites in DSAP lesioned rats indicates dependence of these responses on CA neurons. Hindbrain Catecholamine Neurons Activate Orexin Neurons During Systemic Glucoprivation in Male Rats. Endocrinology, 156(8), 2807–2820. doi:10.1210/en.2015-1138