ESTIMATION OF CHOLINESTERASE AND CHOLINE ACETYLTRANSFERASE IN BOVINE ANTERIOR PITUITARY, POSTERIOR PITUITARY, AND PINEAL BODY*

Authors

  • F. S. LaBella,

    1. Department of Pharmacology and Therapeutics, University of Manitoba Faculty of Medicine, Winnipeg 3, Canada
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    • Medical Research Associate, Medical Research Council of Canada.

  • S. Shin

    1. Department of Pharmacology and Therapeutics, University of Manitoba Faculty of Medicine, Winnipeg 3, Canada
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  • *

    Supported by United States Public Health Service grant AM05896 and the Medical Research Council of Canada.

Abstract

Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were estimated colorimetrically with thiocholine (SCh) esters as substrates in homogenates of bovine anterior pituitary (AP), posterior pituitary (PP), and pineal body (PB), and the levels were referred to those of whole rat brain. The levels of BuChE were very similar in all four tissues, approximately 10.25 μm-BuSCh hydrolysed/g tissue/hr; indicating that this enzymic activity represents a common structural component, perhaps vascular elements. Acetyl-thiocholine (ASCh) hydrolysis by AChE for brain, PP, PB, and AP was 338, 37,24, and 6 μm/g/hr, respectively. Choline acetyltransferase (ChAc) was estimated by the formation of [14C]acetylcholine from [14C]acetyl CoA. ChAc activity of posterior pituitary was generally found to be 15–20 per cent that of brain; the activity was always lowest in the anterior pituitary and pineal body, sometimes undetectable, but generally 5–10 per cent that of brain. The basis for the interpretation that cholinergic components in the posterior pituitary are due to acetylcholme-containing nerve endings and in anterior pituitary and pineal body to axons of sympathetic neurons was discussed.

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