Intrinsic nerve circuits of the gastrointestinal tract: identification of drug targets.

Advances in understanding the pathophysiological role of neurotransmitters and neurotransmitter receptors that are expressed by neurons of the intrinsic circuits of the intestine will aid the selection of new drug targets for therapeutic compounds. The major components of the intrinsic circuits for motility, secretion and blood flow control in the small and large intestines have been identified in recent years, although the intrinsic circuits in the stomach are still not adequately determined. In the guinea-pig small intestine, where circuits have been most accurately defined, there are 14 functionally identified neuron types, each with a characterised pharmacology of transmission.