Improved conditioned avoidance learning by oxytocin administration in high-emotional male Sprague-Dawley rats.
OBJECTIVE
To examine anti-stress-like properties of oxytocin as a means to improve conditioned avoidance learning in a low-performing, high-emotional, stock of Sprague-Dawley male rats.


METHODS
Adult male rats of two stocks of the Sprague-Dawley strain, designated Stock A and Stock B, were treated daily with oxytocin (1 mg kg(-1) s. c.) for 5 days preceding four daily conditioned avoidance acquisition sessions (approximately 20 trials per 15 min session). The Stock B animals were previously characterized as high-emotional based on [1] elevated plasma corticosterone, and lowered plasma oxytocin, levels and [2] decreased reaction time and an increased startle amplitude to an acoustic stimulation. Finally, [3] these animals were unable to acquire a conditioned avoidance response within 5 days of training.


RESULTS
The Stock A animals rapidly and statistically significantly acquired the avoidance behaviour within 4 days of daily training, whereas Stock B animals did not improve over this time period. The avoidance performance of Stock B animals was markedly and statistically significantly improved by the oxytocin pre-treatment, whereas the performance of Stock A animals was not affected by the same oxytocin treatment.


CONCLUSIONS
Pre-treatment with oxytocin markedly improved avoidance learning in the Stock B high-emotional animals. It is suggested that the improvement is due to previously demonstrated anti-stress-like properties of oxytocin, rendering the animals able to successfully cope with the demands of the conditioned avoidance situation.
Uvnäs-Moberg
K
K
Department of Physiology and Pharmacology, Division of Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden.
Eklund
M
M
Hillegaart
V
V
Ahlenius
S
S
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D004644:Emotions / Q000187:drug effects*; D004924:Escape Reaction / Q000187:drug effects*; D008297:Male; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D010121:Oxytocin