RELATIONSHIP OF NK3 RECEPTOR-IMMUNOREACTIVITY TO SUBPOPULATIONS OF NEURONS IN RAT SPINAL-CORD

The distribution of immunoreactivity to the neurokinins receptor (NK3R ) was examined in segments C7, T11-12, L1-2, and L4-6 of the rat spina l cord. NK3R immunoreactivity was visualized by using two antisera gen erated against sequences of amino acids contained in the C-terminal re gion of the NK3R. NK3R-immunoreactive cells mere numerous in the subst antia gelatinosa of all spinal segments examined as well as the dorsal commissural nucleus of spinal segments L1-2. Isolated, immunoreactive cells were scattered throughout other regions of the spinal cord. The relationship of NK3R-immunoreactivity with neurons was demonstrated b y colocalization with microtubule associated protein 2-immunoreactivit y in individual cells. Within neurons, NK3R-immunoreactivity was assoc iated predominately with the plasma membrane of cell bodies and dendri tes. Within the substantia gelatinosa, 86% of nitric oxide synthase (N OS)-immunoreactive neurons were also NK3R-immunoreactive. Although NOS -immunoreactive neurons were found throughout all other regions of the spinal cord in the segments examined, these were not NK3R-immunoreact ive. When preganglionic sympathetic neurons in spinal segments T11-12 and L1-2 were visualized by intraperitoneal injection of Fluorogold, l ess than 1% of the Fluorogold-labeled neurons were also immunoreactive for NK3R. The large number of NK3R-immunoreactive neurons in the subs tantia gelatinosa suggests that some effects of tachykinins on somatos ensation may be mediated by NK3R. (C) 1997 Wiley-Liss, Inc.