Abstract
Rationale. Swim stress decreases extracellular serotonin (5-HT) levels in the rat lateral septum, and adaptation to this effect occurs with repeated swimming. Corticotropin-releasing factor (CRF) administered into the dorsal raphe nucleus (DRN) also decreases 5-HT release in the lateral septum, suggesting that CRF may mediate the effects of swim stress.
Objectives. The hypothesis that endogenous CRF mediates the reduction of 5-HT levels in the lateral septum evoked by swim stress and is involved in the adaptation that occurs with repeated swim stress was tested.
Methods. Extracellular 5-HT levels in rat lateral septum were quantified by means of in vivo microdialysis. Extracellular single unit activity was recorded from the DRN.
Results. Intracerebroventricular (i.c.v.) administration of a CRF receptor antagonist prevented the ability of swim stress to decrease 5-HT release in the lateral septum. Prior exposure to swim stress reduced the ability of both CRF (i.c.v.) and a subsequent swim stress to decrease lateral septum 5-HT release (cross adaptation). Additionally, the effects of CRF, administered into the DRN, on DR neuronal discharge were attenuated in rats with a history of swim stress. Finally, administration of a CRF receptor antagonist (i.c.v.) between two swim stress sessions restored the neurochemical response to swim stress (i.e., 5-HT levels were reduced during the second exposure to swim).
Conclusions. Endogenous CRF modulates 5-HT transmission during acute environmental stress and is also integral to adaptation of the 5-HT response produced by repeated stress. Modulation of the 5-HT system by CRF during acute stress may underlie certain coping behaviors, while stress-induced adaptation of this effect may be involved in psychiatric manifestations of repeated stress.
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Price, M.L., Kirby, L.G., Valentino, R.J. et al. Evidence for corticotropin-releasing factor regulation of serotonin in the lateral septum during acute swim stress: adaptation produced by repeated swimming. Psychopharmacology 162, 406–414 (2002). https://doi.org/10.1007/s00213-002-1114-2
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DOI: https://doi.org/10.1007/s00213-002-1114-2