Biochemical and histochemical observations on the postnatal development of cholinesterases in the sympathetic ganglion of the rat

Abstract

The activities of acetylcholinesterase and non-specific cholinesterase were measured by automatic titration in the superior cervical ganglia of albino rats aged o (newborn), 3, 6, 12, 24 and 90 days using acetylcholine and butyrylcholine as substrates and BW 284 C51 for distinguishing acetylcholinesterase from non-specific cholinesterase. The total cholinesterase activity was 29 μmol/g protein/min at birth but increased to 185 μmol/g protein/min on the 90th postnatal day. The acetylcholinesterase activity was 24 μmol/g protein/min at birth; it increased mainly between the 24th and 90th postnatal day, an increase being 44 to 131 μmol/g protein/min. The non-specific cholinesterase activity was still low on the 6th day (18 μmol/g protein/min) but on the 12th postnatal day reached almost the adult level of 57 μmol/g protein/min. Acetylcholinesterase was demonstrated histochemically with acetylthiocholine as substrate used in conjunction with iso-OMPA. Throughout postnatal development acetylcholinesterase was present in the cytoplasm of the sympathetic nerve cells and there was great variation in its activity in individual cells. The average activity increased with age up to the 24th day but showed little change thereafter. Fibres between the nerve cells first exhibited acetylcholinesterase activity on the 12th day. The number of acetylcholinesterase-positive fibres increased until the animals were adult. Non-specific cholinesterase activity, demonstrated using butyrylthiocholine with BW 284 C51 as inhibitor, was observed soon after birth in the cytoplasm of young nerve cells. Its activity increased until the 12th day but decreased thereafter in most nerve cells and increased in satellite and Schwann cells. However, some nerve cells showed a strong non-specific cholinesterase activity from the 12th to 90th day. It is concluded that (1) acetylcholinesterase activity is connected with both the differentiation and the prospective function of the sympathetic nerve cells; (2) non-specific cholinesterase plays an active role in the maturation of young nerve cells but is permanently present in some, presumably non-adrenergic, mature nerve cells and glial cells; and (3) the cholinesterases shown an adult pattern about 3 weeks after birth.