Increased drinking in mutant mice with truncated M5 muscarinic receptor genes.

The rarest and least understood of the muscarinic receptors is the M5 subtype. Recombinant methods were used to create mutant mice with a deletion in the third intracellular loop of the M5 receptor gene. Salivation induced by the nonselective muscarinic agonist pilocarpine (1 mg/kg s.