Modulation of catecholamine synthesizing and degrading enzymes by swimming and emotional excitation in the rat
The activities of catecholamine enzymes have been determined in adrenal glands of Wistar rats following 2 and 6 weeks of intermittent swimming (max. 2 × 90 min daily in 35 °C warm water) and 6 weeks intermittent experimentally induced emotional excitation (“shock-induced aggression”)- Following 2 weeks swimming, there was no significant change in activities of phenylethanolamine-N-methyltrans-ferase (PNMT) and catechol-O-methyltransferase (COMT); monoamine oxidase (MAO) activity was significantly increased. In contrast, a swimming routine extending over 6 weeks resulted in significantly reduced activities of PNMT, COMT, and MAO. Intermittent emotional excitation of the same time-course extending over 6 weeks did not significantly affect the enzyme activities. Qualitatively similar changes were observed in the heart. It is concluded that the reduced activities of PNMT, COMT and MAO following 6 weeks swimming do not arise from stress elicited by the present swimming routine, but can be attributed to the effects of exercise, such as reduced sympathetic nerve activity.
In order to test the concept of altered enzyme levels, particularly of PNMT, as being diagnostic for changes in transmitter utilization, rats were treated with drugs known to interfere with normal catecholamine turnover. For this purpose, rats were chronically infused with isoproterenol and propranolol which are expected to induce a reflex increase in sympathetic activity. The expected effect on catecholamine enzymes would thus be opposite to that observed following swimming exercise. The rats were infused with isoproterenol (0.02 and 5 mg/kg daily) and propranolol (5 mg/kg daily) using osmotic minipumps. The lower dose of isoproterenol resulted in a significant increase of only PNMT activity in adrenal glands, whereas the higher dose of isoproterenol additionally increased significantly COMT and MAO activities. Propranolol induced a significant increase in COMT and PNMT activities in adrenal glands. In the heart, the activities of PNMT, COMT, and MAO were increased following isoproterenol and propranolol infusion. These results corroborate the above conclusions on 6 weeks’ swimming-induced changes in catecholamine enzymes as arising predominantly from effects of exercise.
Key wordsswimming emotional excitation stress exercise monoamine oxidase catechol-O-methyltransferase phenylethanolamine-N-methyltransferase isoproterenol propranolol
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- 2.Bhagat, B., W. J. Burke, J. W. Davis: Effect of reserpine on the activity of adrenal enzymes involved in the synthesis of adrenaline. Brit. J. Pharmacol. 43, 819–827 (1971).Google Scholar
- 3.Bhagat, B. D.: Regulation of norepinephrine contents in cardiac sympathetic neuron during high impulse activity: alterations in monoamine oxidase activity. Recent Advan. in Studies on Cardiac Struct. Metabolism 3, 343–356 (1973).Google Scholar
- 4.Bhagat, B. D., J. M. Sullivan, N. S. Dhalla: Alterations in norepinephrine pattern in the damaged myocardium in the rat. Recent Advan. in Studies on Cardiac Struct. Metabolism 6, 159–165 (1975).Google Scholar
- 5.Ciaranello, R. D., G. F. Wooten, J. Axelrod: Regulation of rat adrenal dopamine β-hydroxylase. II. Receptor interaction in the regulation of enzyme synthesis and degradation. Brain Res. 113, 349–362 (1976).Google Scholar
- 9.Jacob, R., G. Kissling, G. Ebrecht, C. Holubarsch, I. Medugorac, H. Rupp: Adaptive and pathological alterations in experimental cardiac hypertrophy. In: Advances in Myocardiology, Vol. 4, Chazov, E., V. Saks, G. Rona (eds.), pp. 55–78. Plenum Medical Book Company (New York 1982).Google Scholar
- 12.Kvetňanský, R., T. Torda, E. Jahnová, N. Saleh: Activity of catecholamine degrading enzymes in rat adrenal medulla and cortex after acute and repeated stress. Endocr. Exp. 9, 79–86 (1975).Google Scholar
- 13.Kvetňanský, R., I. Albreeht, T. Torda, N. Saleh, E. Jahnova, L. Mikulaj: Effect of stress on catecholamine synthesizing and degrading enzymes in control and spontaneously hypertensive rats. In: Catecholamines and Stress, Usdin, E., R. Kvetňanský, I. J. Kopin (eds.), 237–249. Pergamon Press (Oxford 1976).Google Scholar
- 14.Kvetňanský, R.: Recent progress in catecholamines under stress. In: Catecholamines and Stress: Recent Advances, Usdin, E., R. Kvetňanský, I. J. Kopin (eds.), 7–18. Elsevier North Holland, Inc. (Amsterdam 1980).Google Scholar
- 18.Östman-Smith, L: Adaptive changes in the sympathetic nervous system and some effector organs of the rat following long term exercise or cold acclimation and the role of cardiac sympathetic nerves in the genesis of compensatory cardiac hypertrophy. Acta Physiol. Scand. Suppl. 477, 1–118 (1979).PubMedGoogle Scholar
- 20.Rupp, H., H.-R. Felbier, R. Jacob: Blood pressure and cardiac myosin heterogeneity in the rat as influenced by swimming and emotional excitation. This issue, p. 274–281.Google Scholar