Ultrastructural evidence for gamma aminobutyric acid-immunoreactive synapses on somatostatin-immunoreactive perikarya in the periventricular anterior hypothalamus.
Somatostatin-immunoreactive perikarya in the periventricular anterior hypothalamus were demonstrated to be surrounded by gamma aminobutyric acid GABA-immunoreactive nerve terminals, by combining pre-embedding immunocytochemistry for somatostatin and gold labelling post-embedding immunocytochemistry for GABA. Ultrastructural studies revealed that in each 100-nm section, cells immunoreactive for somatostatin (n = 62) were contacted by a mean of 7.6 +/- 0.4 terminal profiles of which 3.0 +/- 0.3 (40%) were GABA-immunoreactive. Most GABA-immunoreactive terminals contained clear rounded vesicles and, where synaptic specializations were well demonstrated, appeared to be symmetric. The finding provides evidence that there is a significant GABA input to somatostatin neurons, an observation strengthening the hypothesis that GABA may inhibit somatostatin neurons, thereby causing increased secretion of growth hormone.
D000818:Animals; D007032:Hypothalamus, Anterior / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D013004:Somatostatin; D005680:gamma-Aminobutyric Acid