Immunoreactivity of neurotensin(NT) and substance P (SP) were studied by means of PAP method with simultaneous immunocytochemical double staining on the same sections using diaminobenzidine (DAB) for SP and benzidinc dihydrochloride(BDHC) for NT as the chromogens for light and electron microscopy in dorsal horn of spinal cord of rat treated with colchicinc. In our hands the reaction products of DAB and BDHC is quite discernible, under LM the former is brown and later is blue; under EM DAB reaction product is homogeneous and diffuse electron opaque while BDHC reaction product is patch electron opaque, it is a new but simpler approach to demonstrate two antigens simultaneously in the same ultrathin section. It would be conformable further to the studies of morphological and functional relationships between different kinds of neurons. The results showed that NT-like immunoreactive (NT-LI) perikarya were mainly located in lamina Ⅱi and out layer of lamina Ⅲ and NT-LI terminals were mainly located in laminae Ⅰ-Ⅲ. Under EM the NT-LI axon terminals may synapse with the unlabeled axon or unlabeled dendrites. SP-like immunoreactive (SP-LI) perikarya were mainly located in lamina Ⅱ. The density of SP-LI terminals were higher in laminae Ⅰ-Ⅱ, while axo (SP)-axonic (SP), axo (SP)-somatic (SP) synapses were identified with EM. In double labelling sections, furthermore under EM, it was found that NT-LI axon terminal (BDHC patch like electron opaque reaction products)can synapse or contact with SP-LI axon (DAB diffuse electron opaque reaction products). Our results suggested that NT-and SP-containing neurons and terminals in dorsal horn might participate in regulating process of primary sensory transmission.

In this study histochemical method was used. It has been found that on the seventh day after epidural administration of capsaicin substance p like immuno- reactivity (SPAR) in laminae Ⅰ-Ⅱ of dorsal horn of spinal cord decreased obv- iously as compared with that of vehicle treated animals, meanwhile, the activity of fluoride resistant acid phosphatase (FRAP) in both laminae Ⅱ of dorsal horn of spinal cord and the B-type cells of spinal ganglion disappeared. On the cont- rary the Leu-enkephalin immunoreactivity (ENK-IR) in laminae Ⅰ-Ⅲ of dorsal horn of spinal cord apparently increased as compared with that in vehicle group. the evidence from functional measurement showed that capsaicin can raise pain threshold, however, vehicle didnot have obvious influence on pain threshold. The foregoing results suggest that epidural administration of capsaicin in adult rat can effect the level of neurontransmitters, the activity of enzymes and block the con- duction of the primary afferent C fibers; the capsaicin-sensitive C fibers may have relationship with the ENK-containing interneurons in dorsal horn of spinal cord.

The subunit ?_0 of guanine nucleotide- binding protein, in the areas of rat brain and spinal cord was localized by immunohistochemical methods. It was found that in the rat brain, specific ?_0-like immunoreactivity(?_0-Li) displayed regional heterogeneity, a high density of ?_0-Li revealed in neuropil, and somatic membranes as well as the neuronal processes.Most intense ?_0-Li can be seen in substantia nigra(pars reticulata), interpcduncular nucleus, habenulo-interpeduncular tract, strata oriens and radiatum of the hippocampus, and substantia gelatinosa of the spinal cord. There are also areas of moderate staining ie: the molecular layer of cerebral and cerebellar cortex, habenula, caudate-putamen complexes, the midline nuclei of thalamus and hypothalamus, periaqueductal grey, grey layers of superior colliculus, the olivo-cerebellar tract and the spinal tract of the trigeminal nerve as well. By contrast, the immunoreactvity of ?_0 in septal nuclei, globus pallidus, red nucleus, and the regions adjacent canalis centralis of the spinal cord showed much weaker. In addition, on the membranes and the processes of the neuronal cell bodies in the periaqueductal grey, substantia nigra, reticular formation, medial geniculate body and the nucleus of the trapezoid body were ?_0-Li positive.The results of AChE staining revealed that the AChE-positivc nerve terminals was coinsident with the presence of ?_0-Li in the following regions. For instance: the molecular layer of cerebral cortex, hippocampus, spinal tract of the trigminal nerve, and substantia gelatinosa of the spinal cord, where both the ?_0-Li and the AChE activity were positive. It is suggested that ?_0 subunit of Go-protein in brain might play roles in membrane signal transduction, and might have some relationship with cholinergic nerve.