Localisation of [3H] clonidine binding in rat neurohypophysis by means of electron-microscopic autoradiography.
Electron-microscopic autoradiography of rat neurohypophyses treated with [3H] clonidine, an alpha 2-agonist, showed that binding apparently occurred preferentially at the neurosecretory endings and blood vessels rather than on the pituicytes. Since it is known that clonidine has a high affinity for plasma proteins, the distribution over the neurosecretory nerve endings would suggest the existence of presynaptic alpha 2-binding sites on neurosecretory neurones, which could indicate a regulatory function for catecholamines in neurohypophysial hormone release.
D000818:Animals; D003000:Clonidine / Q000378:metabolism*; D008297:Male; D008854:Microscopy, Electron; D010904:Pituitary Gland, Posterior / Q000098:blood supply / Q000294:innervation / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism
D011942:Receptors, Adrenergic, alpha; D003000:Clonidine