THE SYNAPSES BETWEEN CHOLINERGIC NEURONS AND SUBSTANCE P TERMINALS OF THE RAT SACRAL VENTRAL HORN A DOUBLE IMMUNOSTAINING METHOD / 解剖学报

ABSTRACT

The relationships between cholinergic neurons and SP terminals were examined in the rat sacral ventral horn at the light and electron microscopic levels by means of double immunostaining methods. Cholinergic neurons were labeled by a monoclonal antibody to choline acetyltransferase (CHAT) with the avidin-biotin technique and stained bluish-green by indolyl-?-galactoside reaction products with ?-galactosidase as a marker. On the same sections, SP fibers were labeled by polyclonal antisera to SP after application of the peroxidase-antiperoxidase (PAP) method and stained brown by diaminobenzidine (DAB)reaction. At the light microscopic level CHAT-I neurons stained bluish-green and SP- I fibers Stained brown were found in the ventral horn. At the electron microscopic level, many asymmetrical axodendritic synapses(type I of Gray)were observed between CHAT-I dendrites and SP-I terminals in the ventral horn, but axosomatic synapses and symmetrical synapses (type I of Gray) were hardly detected. These results indicate that SP-I terminals make direct synapses with CHAT-I motoneurons of sacral ventral horn. These synapses may be predominantly excitatory and have importance in the control of muscular constriction.