Synaptology of lhrh neurons in rat preoptic area
Witkin, J.W.; Silverman A J.
Peptides (New York) 6(2): 263-272
The ultrastructural appearance of LHRH immunoreactive elements was studied in the medial preoptic area (MPOA) of adult male Fischer 344 rats. The distribution and morphology of innervation of the LHRH neuron was determined. Although not numerous, both axo-somatic and axo-dendritic synapses were present and generally of the asymmetric (Gray's II) category. Analyses of 56 profiles of 11 separate perikarya revealed only 7 axo-somatic terminals. The synaptic input to LHRH dendrites was a fraction of that to non-identified dendrites in the same electron micrographic fields; 0.4% of LHRH dendritic membrane was in synaptic contact compared to 6.6% of nonidentified dendritic membrane. In addition to receiving an input, LHRH processes were also seen to make synapses onto non-immunoreactive elements. Close examination of this material for evidence of contact between LHRH elements revealed 2 clear examples of synaptic interaction and several instances of close association in which no other elements intervened.