Volume 86, Issue 1 p. 33-41
Free Access

Effects of conditioned running on plasma, liver and brain tryptophan and on brain 5-hydroxytryptamine metabolism of the rat

F. Chaouloff

F. Chaouloff

Department of Pharmacology, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris

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J.L. Elghozi

J.L. Elghozi

Department of Pharmacology, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris

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Y. Guezennec

Y. Guezennec

LCBA-CERMA, 75015 Paris-Armées, France

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D. Laude

D. Laude

Department of Pharmacology, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris

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First published: September 1985
Citations: 122

Abstract

  • 1

    An investigation was made into the effects of conditioned running (1 h and 2 h at 20 m min−1), which accelerates lipolysis, on the concentrations of tryptophan (Trp) in plasma, liver and brain and on 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels in brain.

  • 2

    Running caused time-dependent increases in plasma free Trp and brain Trp of the rat, leading to increased brain 5-HT turnover as revealed by higher amounts of its metabolite, 5-HIAA. The ratio of brain Trp to plasma free Trp was decreased after 2 h of running.

  • 3

    Liver Trp content rose only after 3 h of running, while liver unesterified fatty acid (UFA) concentrations remained unmodified.

  • 4

    A comparison between food deprivation and running (both of which promote lipolysis) was performed. Running for 2 h affected to the same extent plasma Trp disposition when compared with 24 h food deprivation. Nevertheless, the ratio of brain Trp to plasma free Trp was decreased in the food-deprived rats, when compared to the runners.

  • 5

    Valine, an inhibitor of entry of Trp into the brain decreased its level there to the same extent in both controls and 1 h runners.

  • 6

    Nicotinic acid, which inhibits fat catabolism, completely abolished the plasma UFA increase induced by 1 h of running. The drug did not affect plasma free Trp, brain Trp, 5-HT or 5-HIAA but enhanced plasma total Trp level.

  • 7

    Naloxone, an opiate antagonist, which decreased running-induced lipolysis, did not alter plasma Trp disposition.

  • 8

    Desipramine, an antidepressant compound, affected only peripheral Trp concentrations of the runners. Plasma free and total Trp concentrations were increased in desipramine-treated runners, compared with saline-treated runners. In addition, desipramine increased the ratio of brain Trp to plasma free Trp of the runners. Brain 5-HT and 5-HIAA were increased in both desipramine-treated controls and runners.

  • 9

    The results suggest that running, which like food deprivation accelerates lipolysis, increases brain Trp content and then 5-HT turnover. Comparison of these two physiological situations suggests that effectiveness of brain Trp entry is much more altered by fasting.