ABSTRACT
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.