An uneven distribution of choline acetyltransferase activity in the pituiatry neurointermediate lobe of the rat.

The neurointermediate lobe of the pituitary gland of male rats was assayed for choline acetyltransferase (CAT) activity. Precise microsample punches were obtained from neurohypophysial tissue, pure pars intermedia tissue and from the junction area between them. The level of CAT activity (pmol/h per microgram protein) in the neurohypophysis, pars intermedia and junction area were 0.390 +/- 0.038 (S.E.M.), 0.228 +/- 0.042 and 1.824 +/- 0.268 respectively. These values show an uneven distribution of CAT in the neurointermediate lobe. The hypothesis of a cholinergic system located in the junction area has been advanced.