Intrinsic tyrosine hydroxylase (TH) immunoreactive axons synapse with TH immunopositive neurons in the rat arcuate nucleus.

Synaptic connections were demonstrated between tyrosine hydroxylase (TH) immunoreactive axons and dendrites in the arcuate nucleus of the rat, by electron microscopic immunocytochemistry. These connections were primarily found in the lateral part of the nucleus. The results of two types of medial-dorsal-lateral surgical de-afferentation suggest that the TH-TH contacts represent intrinsic connections.