Renin-like effects of NGF evaluated using renin-angiotensin antagonists

Intracranial injection of angiotensin II (AII) or activation of the cerebral isorenin-angiotensin system with intracranial renin causes an immediate thirst and a delayed sodium appetite in the rat. Nerve growth factor (NGF), a polypeptide trophic factor for peripheral sympathetic and sensory neurones, has also been reported to be a potent stimulus to thirst and sodium appetite when injected into the brain of the rat. Lewis et al. drew attention to the marked similarity between the effects of 2.5S NGF and renin on thirst and sodium appetite and suggested that the NGF responses were mediated by the cerebral isorenin-angiotensin system. We report here that NGF-induced thirst and sodium appetite, as well as increased blood pressure and increase ornithine decarboxylase activity in the brain and liver, depend on the formation of AII (see also ref. 6).