Hypothalamic knife cuts attenuate the pressor responses to angiotensin II

The effects of coronal knife cuts posterior to the organum vasculosum of the lamina terminalis on pressor responses to intraventricular (i.v.t.) and intravenous (i.v.) angiotensin II (AII), i.v.t. hypertonic NaCl and i.v. norepinephrine were tested in the rat. Drinking responses to i.v.t. AII were also measured. Knife cuts attenuated the blood pressure responses to i.v.t. and i.v. AII, but not to i.v.t. hypertonic NaCl and i.v. norepinephrine. Drinking responses to i.v.t. AII were not reduced. These data indicate that neural pathways which mediate the pressor response to i.v.t. AII pass through this portion of the hypothalamus and are distinct from the neural pathways which mediate drinking to central AII.