Centrally administered neurotensin inhibits pentobarbital metabolism in mice but not in rats.

Neurotensin (NT), a tridecapeptide with a widespread and uneven distribution within the central nervous system of mammals, is known to be involved in a variety of physiological, behavioral, endocrine and biochemical functions. Groups of rats and mice were given i.p. injections of pentobarbital followed by intracisternal administration of NT or saline. Following decapitation, the plasma, liver and brain concentrations of pentobarbital were measured with a gas chromatographic/mass fragmentographic method. In the mice, but not in the rats, the NT injection caused a substantial inhibition of the pentobarbital metabolism and a prolongation of the sleeping time. The mechanism(s) behind this inhibition still remains unclear.