PT  - JOURNAL ARTICLE
AU  - Bhatnagar, R. K.
AU  - Moore, K. E.
TI  - REGULATION OF NOREPINEPHRINE CONTENTS IN NEURONAL CELL BODIES AND TERMINALS DURING AND AFTER CESSATION OF PREGANGLIONIC STIMULATION
DP  - 1972 Feb 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 265--276
VI  - 180
IP  - 2
4099  - http://jpet.aspetjournals.org/content/180/2/265.short
4100  - http://jpet.aspetjournals.org/content/180/2/265.full
SO  - J Pharmacol Exp Ther1972 Feb 01; 180
AB  - The contents of norepinephrine (NE) in cell bodies (superior cervical ganglia) and terminals (submaxillary salivary glands) of postganglionic sympathetic neurons were determined in cats during, immediately after and two and six hours after cessation of three hours of preganglionic electrical stimulation. In ganglia, neither the NE contents nor the rates of formation of NE-14C from tyrosine-l4C or dopamine-14C were altered during the stimulation or poststimulation periods. Stimulation for one hour reduced the amount of NE in terminals to 40% of control; this reduced content was maintained when stimulation continued for three hours. The stimulus-induced reduction of NE in terminals was enhanced if either synthesis or reuptake of NE was blocked by α-methyltyrosine or desmethylimipramine, respectively. During the poststimulation period the amount of NE in the terminals increased to 65% of control within two hours, and then remained at this reduced value during the next four hours. α-Methyltyrosine, but not desmethylimipramine, prevented this partial recovery of NE. The synthesis of NE-14C from tyrosine-14C increased during and immediately after cessation of stimulation, but six hours later the conversion of tyrosine-14C to NE-14C was the same in stimulated and non-stimulated terminals. The failure of NE to return to control values after stimulation was not the result of reduced activity of dopamine-β-hydroxylase because six hours after cessation of stimulation the conversion of dopamine-14C to NE-14C was accelerated. Thus, recovery of NE stores in nerve terminals after depletion by preganglionic stimulation is effected by an increased rate of synthesis of this amine from both tyrosine, probably involving release of feedback inhibition, and from dopamine, involving an unknown mechanism. © 1972 by The Williams & Wilkins Co.