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METABOLIC AND THERMOREGULATORY RESPONSES OF THE RAT MAINTAINED IN ACRYLIC OR WIRE-SCREEN CAGES: IMPLICATIONS FOR PHARMACOLOGICAL STUDIES
Citation:
Gordon, C. METABOLIC AND THERMOREGULATORY RESPONSES OF THE RAT MAINTAINED IN ACRYLIC OR WIRE-SCREEN CAGES: IMPLICATIONS FOR PHARMACOLOGICAL STUDIES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/110.
Description:
Laboratory rodents are usually housed and studied in cages with walls and floor made of ventilated metal or solid plastic materials. It should be recognized that a rodent's thermoregulatory requirements will vary in metal and plastic cages; and it is likely that its metabolic response to chemical agents will also vary depending on the cage type. To address this issue, autonomic thermoregulatory responses were measured in rats of the Long-Evans (LE) and Fischer (F344) strains when placed in either a metal, wire-mesh cage with no bedding material or a plastic cage with wood chip bedding material. Metabolic rate (M), evaporative water loss (E), thermal conductance (C), tail skin (Ts) and core temperature (Tc) were measured at ambient temperatures (Ta) of 20, 30, and 32.5 degrees C. Plastic cages led to a higher Ts and lower M at cool Ta's, but markedly higher Tc's and M at higher Ta's. The rise in C with increasing Ta was significantly reduced in rats kept in plastic cages. The LE rats were more susceptible to hyperthermia when housed in the plastic cages at warmer Ta's than were F344 rats. To assess the impact of cage type on thermoregulatory response to a