Choline acetyltransferase activity in murine thymus

Abstract

Murine thymus has been demonstrated to contain both cholinergic receptors and acetylcholinesterase activity. In the present study we have investigated the presence of the enzyme choline acetyltransferase in this organ, which is responsible for the synthesis of acetylcholine. Results reported here demonstrate that (1) an appreciable amount of the enzyme is already present in the thymus on the day of birth; (2) its expression is developmentally regulated; and (3) thymic atrophy, induced in young (2-week-old) and adult (6-week-old) mice by i.p. injection of hydrocortisone for 2 days, is accompanied by significant reduction of choline acetyltransferase activity only in young mice. Altogether these results demonstrate the presence in the murine thymus of functionally relevant markers of the cholinergic system that might interface the interactions between the nervous and immune systems.

Detection of choline‐acetyltransferase activity in lymphocytes

“…In contrast to our findings, Rossi et al (1989) did not find ChAT in sonicated suspensions of murine thymocytes. In accordance with the same authors (Tria et al, 1992), we could not thus far detect ChAT in thymic tissue by immunocytochemistry using a monoclonal (Chemicon MAB305) or polyclonal (Chemicon AB 144) antibody. Attempts to identify ChAT in thymus cells by Western blotting after PAGE also failed.…”

An acetylcholine receptor alpha subunit promoter confers intrathymic expression in transgenic mice. Implications for tolerance of a transgenic self-antigen and for autoreactivity in myasthenia gravis.

“…Acetylcholine and carbamylcholine both enhance TEC proliferation in preconfluent TEC lines (35). The presence of choline acetyltransferase, which is responsible for the synthesis of acetylcholine, has been demonstrated in the thymus (36). Together with our demonstration that AChR transcription is activated in TEC, these reports suggest that cholinergic signals to TEC may regulate thymic differentiation and selection processes.…”

“…Eisele, Pater Institute) in CFA. Blood was collected from the orbital sinus on days 0, 10,20,30,36,48,65,90, and 120. To obtain a doseresponse curve, mice were immunized intraperitoneally with 20, 50, or 100 g/ml ␤ -gal in CFA and blood was collected on days 0, 20, 36, 43, 64, and 82.…”

A Possible Role for Acetylcholine in the Dialogue between Thymocytes and Thymic Stroma

“…We have been able to show that thymocytes express mRNA for choline ace-tyltransferase, and that cellular homogenates exhibit measurable activities of this enzyme. It is noteworthy that the activities measured with isolated thymocytes were identical to those reported by others [25] in tissue homogenates, which were taken as evidence for a cholinergic innervation of the thymus. Thus, our data would suggest that thymic acetylcholine is indeed derived to the major part from lymphocytes, rather than from cholinergic nerve endings.…”