Substance P excitation of rat locus coeruleus neurones.

We have made extracellular recordings from locus coeruleus neurones contained in a pontine slice preparation. The in vitro technique permits application of known concentrations of drugs in the perfusion medium. Substance P excites locus coeruleus neurones in a concentration-dependent manner. The activity of substance P was found to reside in the C terminal region of the molecule. The relative potency of substance P and related peptides suggests that the substance P receptors present within the locus coeruleus are predominately of the substance P-P type. The synthetic analogue [D-Pro2,D-Trp7.9]substance P was not found to antagonise the action of substance P on locus coeruleus neurones.