Stress triggers anhedonia in rats bred for learned helplessness.
Congenitally helpless (cLH) rats, a well-accepted model for depression, show reduced consumption of sweet solutions only under single-housing conditions, indicating anhedonia under stress. We investigated if anhedonic-like behaviour, measured by a reduction of sweetened-condensed milk (SCM) intake and the pleasure-attenuated startle response (PAS), could be induced by an electric foot-shock stress challenge in group-housed rats. After foot-shock stress, reduced SCM intake was observed in cLH rats compared to non-helpless (cNLH) rats. Furthermore, cLH rats also showed a decreased PAS, indicating deficient reward perception. In summary, we demonstrate that a predisposition for learned helplessness interacts with stress to trigger anhedonic-like behaviour in cLH rats. These findings further add to the validity of congenitally learned helplessness as an animal model of depression, since gene-environment interactions are considered to play a role in the etiology of this disorder.
Enkel
Thomas
T
Dept. of Psychiatry and Psychotherapy, Central Institute of Mental Health, University of Heidelberg, 68159 Mannheim, Germany.
Spanagel
Rainer
R
Vollmayr
Barbara
B
Schneider
Miriam
M
D000161:Acoustic Stimulation / Q000009:adverse effects; D000704:Analysis of Variance; D000818:Animals; D003863:Depression / Q000175:diagnosis / Q000209:etiology*; D004195:Disease Models, Animal; D004597:Electroshock / Q000009:adverse effects; D005518:Food Preferences / Q000502:physiology; D006380:Helplessness, Learned; D051381:Rats; D013216:Reflex, Startle / Q000502:physiology; D012201:Reward; D013315:Stress, Psychological / Q000150:complications* / Q000209:etiology