Marked for life? Effects of early cage-cleaning frequency, delivery batch, and identification tail-marking on rat anxiety profiles.

Journal article

Daily handling of preweanling rats reduces their adult anxiety. Even routine cage-cleaning, involving handling, reduces adult anxiety compared with controls. Cage-cleaning regimes differ between animal breeders, potentially affecting rodent anxiety and experimental results. Here, 92 adult male rats given different cage-cleaning rates as pups, were compared on plus-maze, hyponeophagia, corticosterone, and handling tests. They were pair-housed and half were tail-marked for identification. Anxiety/stress profiles were unaffected by cage-cleaning frequency, suggesting that commercial-typical differences in husbandry contribute little variance to adult rat behavior. However, delivery batch affected some elevated plus-maze measures. Also, tail-marked rats spent three times longer on the plus-maze open arms than their unmarked cagemates, suggesting reduced anxiety, yet paradoxically they showed greater chromodacryorrhoea responses to handling, implying increased aversion to human contact. A follow-up study showed that rats avoided the odor released from the marker pen used. Thus, apparently trivial aspects of procedure can greatly affect experimental results.

Authors: Burn, C; Deacon, R; Mason, G

• Journal: Developmental psychobiology
• Volume: 50
• Issue: 3
• Pages: 266-277
• Publication date: 2008-04-01
• DOI: 10.1002/dev.20279
• EISSN: 1098-2302
• ISSN: 0012-1630
• Language: English
• Keywords: Corticosterone; Avoidance Learning; Male; Feeding Behavior; Adaptation, Psychological; Rats, Wistar; Odors; Social Environment; Anxiety; Handling (Psychology); Rats; Animals, Newborn; Animals; Animal Husbandry; Weaning; Arousal; Maze Learning