Enkephalinergic synaptic axon terminals on serotoninergic neurons in the dorsal raphe nucleus of the rat: an electron microscopic study by the double immunostaining method.
Met-enkephalinergic synaptic axon terminals on serotoninergic neurons in the dorsal raphe nucleus of the rat were observed with double immunostaining at the electron microscopic level. Met-enkephalin-like immunoreactive axon terminals were found to make asymmetrical or symmetrical synaptic contacts with serotonin-like immunoreactive nerve cell bodies and dendrites. The findings suggest that opioid-containing neurons modulate serotoninergic neurons through synapses in the dorsal raphe nucleus.