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5-HT1A Receptor Activation before Acute Stress Counteracted the Induced Long-Term Behavioral Effects


Address for correspondence: Dr. Luis J. Santín, Department of Psychobiology, School of Psychology, University of Malaga, Campus de Teatinos s/n, 29071, Málaga, Spain. Fax: 952-132516. e-mail:


Abstract: The long-term behavioral consequences of acute immobilization (IMMO) in rats and the effects of 5-HT1A receptor activation (8-OH-DPAT: 0.3 mg/kg, sc) were studied. Corticosterone levels after IMMO with previous 8-OH-DPAT treatment were also studied. Twenty-four hours after IMMO (3 h), rats performed conditioned (passive avoidance) and unconditioned (escape behavior) anxiety tests in the elevated T maze. Pre-exposure to IMMO induces long-term behavioral changes in contrast with control rats. These behavioral alterations include an increase of anxiogenic responses, such as exploratory behavior and passive avoidance response. This effect was counteracted by 8-OH-DPAT pretreatment and reversed by WAY-100635 when administered before 8-OH-DPAT. Serum corticosterone levels increased during the first hour of stress and after 8-OH-DPAT administration. Our results support the hypothesis that involvement of acute stress is crucial in the anxiety-like behaviors and in the potentiation of fear. The activation of 5-HT1A receptors counteracted the long-term effects induced by IMMO.