Isolation rearing-induced disruption of prepulse inhibition: further evidence for fragility of the response.
The present study investigated isolation-induced disruptions of prepulse inhibition (PPI), and effects on locomotor activity as a function of home caging condition (sawdust vs grid-floor) in the Wistar rat. Isolates reared in grid-floor cages did not show a disruption of PPI. However, when isolates were reared in sawdust cages, a PPI deficit was evident. In an open field environment, isolates demonstrated significantly increased spontaneous locomotor activity compared to their group-housed counterparts, irrespective of the caging condition employed. Grouped animals reared in grid-floor cages, however, showed reduced activity compared to grouped animals reared in sawdust cages. Although d-amphetamine treatment appeared to enhance locomotor activity selectively in isolates, particularly in those reared in grid-floor cages, this result could be explained by the existing pre-drug activity levels. With respect to PPI, not only were isolation-induced deficits in the Wistar rat difficult to detect in a variable prepulse intensity PPI procedure, but when apparent, the deficits were of a fragile nature. The findings suggest that caging condition may be a critical methodological factor in experiments investigating isolation-induced PPI deficits. Indeed, our results may indicate that rearing animals in grid-floor cages represents a form of chronic mild stress, which can interfere with normal sensorimotor gating mechanisms, in addition to other behaviours.
Weiss
I C
IC
Behavioural Biology Laboratory, Swiss Federal Institute of Technology, Schwerzenbach, Switzerland.
Feldon
J
J
Domeney
A M
AM
D000161:Acoustic Stimulation; D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D003913:Dextroamphetamine / Q000494:pharmacology; D006799:Housing, Animal; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013216:Reflex, Startle / Q000187:drug effects / Q000502:physiology*; D012934:Social Isolation / Q000523:psychology*
D000697:Central Nervous System Stimulants; D003913:Dextroamphetamine