title: Marked for life? Effects of early cage-cleaning frequency, delivery batch, and identification tail-marking on rat anxiety profiles.
abstract: 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.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK. charlotte.burn@worcester.oxon.org
authors.forename: Charlotte C
authors.initials: CC
authors.lastname: Burn
authors.forename: Robert M J
authors.initials: RM
authors.lastname: Deacon
authors.forename: Georgia J
authors.initials: GJ
authors.lastname: Mason
mesh_terms: D000223:Adaptation, Psychological; D000822:Animal Husbandry; D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000503:physiopathology / Q000523:psychology*; D001143:Arousal / Q000502:physiology; D001362:Avoidance Learning; D003345:Corticosterone / Q000097:blood; D005247:Feeding Behavior / Q000502:physiology; D006234:Handling, Psychological; D008297:Male; D018782:Maze Learning; D009812:Odorants; D051381:Rats; D017208:Rats, Wistar; D012931:Social Environment; D014886:Weaning
chemical_list: D003345:Corticosterone