Early exposure to chronic variable stress facilitates the occurrence of anhedonia and enhanced emotional reactions to novel stressors: reversal by naltrexone pretreatment.

ZURITA, A., MARTIJENA, I., CUADRA, G., BRANDAO, M.L. AND MOLINA, V.

BEHAVIOURAL BRAIN RESEARCH

Elsevier

Lugar: Netherlands; Año: 2000 vol. 117 p. 163 - 163

0166-4328

p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify; mso-layout-grid-align: none">The present research studied the influence of an early chronic variable stress (CVS) paradigm  an animal model of depression on behavioral responses to subsequent environmental challenges suggested to model anhedonia and emotional reactions such as anxiety and fear. In order to explore a potential involvement of an endogenous opiate mechanism presumably activated during CVS exposure in the development of such behavioral reactions, in all experiments rats were administered naltrexone (NAL, 2 mg:kg, i.p.) or vehicle (VH) prior to each daily stressor of the CVS procedure. Animals were exposed to CVS and 1 week later tested for sucrose preference (1%) in a free choice paradigm after the presentation or not of a 90-min restraint period. Only C