Depletion of neurons from preoptic area impairs drinking to various dipsogens.

We depleted neurons from the lateral preoptic region (LPO) of rats by iontophoretic application of the neurotoxin kainic acid (KA). Rats with KA-induced damage to LPO neurons drank less water than controls after subcutaneous (SC) administration of: (a) 5 ml of a 1.0 M saline solution or (b) 5 ml of a 30% polyethylene glycol (PG) solution. The drinking response to 1.5 mg/kg angiotensin II (AII) was significantly smaller than was that of controls 15 min but not 1 hour after the SC injection. The experimental animals drank as much water as controls under ad lib conditions and showed normal drinking responses to low concentrations of hypertonic saline (0.5 M) or PG (10% or 20%).