LATERAL SEPTAL VASOPRESSIN IN RATS - ROLE IN SOCIAL AND OBJECT RECOGNITION

The capacity of male rats to remember familiar conspecifics is called social recognition. It is a form of short-term memory modulated by lat eral septal (LS) vasopressin (VP). The specificity of this phenomenon was studied by examining whether recognition of previously investigate d objects is also under control of lateral septal VP. For social recog nition male Wistar rats were confronted with juveniles for 5 min. Re-e xposure to the same juvenile took place after 30 or 120 min, or with a different juvenile after 30 min. This procedure was duplicated for ob ject recognition using a plastic food cup or a 50 ml Erlenmeyer flask. After these initial tests osmotic minipumps and brain cannulae were i mplanted, infusing VP receptor antagonist into the LS (dPTyr(Et)AVP, 1 ng/0.5 mu 1/h, bilateral). Animals were re-tested for social and obje ct recognition using 30 min re-test interval (same juvenile or object) . We reproduced previous reports concerning social recognition; animal s recognized juveniles after 30 min, not after 120 min and VP antagoni st treatment blocked recognition. Testing for object recognition revea led a reduction in investigation time at the 30 min interval (same and different object), but not after 120 min. VP antagonist treatment was unable to block object recognition. The data suggest that, in contras t to social recognition, object recognition reflects a form of habitua tion, which is not under the control of lateral septal VP.