A comparison of the neural regulation of tyrosine hydroxylase activity in sympathetic ganglia of adult mice and rats.

Abstract

AbstractSurgical decentralization of the superior cervical ganglion (SCG) in rats and mice led to a fall in ganglionic tyrosine hydroxylase (T‐OH) activity, and a loss of more than 90 per cent of the preganglionic neurone marker, choline acetyl transferase. T‐OH activity was reduced by more than 50 per cent in mice SCG ten days after surgery, but fell by only 25 per cent in rat SCG after 21 days. The surgical procedure did not cause obvious histo‐logical damage or loss of SCG cells in either species. Both T‐OH and choline acetyl transferase activities in rat and mouse SCG recovered to normal three months after surgery. Reserpine treatment was more effective in rats in causing increased ganglionic T‐OH activity than in mice. Neither decentralization nor reserpine treatment caused any changes in DOPA‐decarboxylase or monoamine oxidase activities in rat SCG. These results demonstrate that T‐OH activity in SCG is subject to trans‐synaptic regulation in both rats and mice; this regulation does not apply to DOPA‐decarboxylase or monoamine oxidase. Differences in basal sympathetic tone may explain the different results obtained in mice and rats.