Abstract
GABA-like immunoreactive neuronal profiles and their synaptic relations in the dorsal raphe nucleus of the rat midbrain were studied by electron microscope Immunocytochemistry, using anti-GABA antibody. By pretreatment with colchicine, the GABA-like immunoreactive neurons could be clearly identified. The perikarya and dendrites usually received synaptic inputs from nonimmunoreactive axon terminals, but also received some synaptic contacts from GABA-like immunoreactive axon terminals. These synapses were usually symmetrical, but sometimes asymmetrical. The GABA-like immunoreactive axon terminals made synapses, usually symmetrical, with non-immunoreactive perikarya and dendrites, although some dendritec synapses were asymmetrical. In the neuropil, a few synapses appeared between GABA-like immunoreactive and non-immunoreactive axon terminals. In this case, the GABA-like immunoreactive axon terminals were either presynaptic or postsynaptic.
