Hypothermia‐induced retrograde amnesia in mature and aged rats

Abstract

Mature (10-month-old) and aged (25-month-old) rats were trained on a passive avoidance task. Following training, rats in each age group were exposed to a hypothermia treatment, restraint alone, or no treatment. The hypothermia treatment involved immersing the mature rats in 4 degrees C water for 12 min and immersing the aged rats in 1 degrees C water for 12 min. This treatment reduced the body temperature of both age groups to an equivalent temperature (22 degrees C). Following immersion, the body temperature of the aged rats continued to decline to a lower level and recovered at a slower rate than the mature rat's temperatures. When all rats were tested 24 hr after training for retention of the avoidance task, mature rats performed better than aged rats when trained with the same shock intensity. Increasing the shock duration for the aged rats eliminated the performance differences on the passive avoidance task between ages. Rats exposed to hypothermia showed poorer retention of the task (i.e., retrograde amnesia) than all control conditions. However, no age differences in the degree of amnesia induced by the hypothermia treatment were apparent once age groups were equated on the intensity of the amnesic agent (hypothermia) and degree of initial learning.

Preventing and alleviating hypothermia-induced amnesia in weanling and young adult rats.

“…perature and immersion time appeared to result in comparable effects on retention performance as indicated by the analyses of the latency test data. These findings replicate those of Hinderliter and Riccio (1976) in that comparable amnesia was produced in weanling and young adult rats and extend those of Hamm (1981), who found similar results with adult and aged rats. These findings have implications for Thompson's (1957) results and conclusions.…”

“…We selected noncontingent footshock as the reminder treatment because it has been shown to be effective in eliminating experimentally induced amnesia in adults (e.g., Miller & Springer, 1972). We selected hypothermia as an amnesic agent because Hinderliter and Riccio (1976) and Hamm (1981), by varying cold-water temperature, were able to equate postimmersion body temperature and the degree of hypothermia-induced retrograde amnesia in animals of various ages. We used parameters of the amnesic treatment demonstrated to be effective in producing comparable retention deficits in weanling and adult rats.…”

Anesthesia and tau pathology

“…It has been well established that hypothermia leads to memory disruption in numerous organisms including rodents (Riccio et al, 1968; Hamm, 1981; Richardson et al, 1983; Santucci et al, 1987). However, the mechanisms by which hypothermia produces memory disruption are not well understood.…”

Anesthesia-induced hypothermia mediates decreased ARC gene and protein expression through ERK/MAPK inactivation

“…In rats, memory loss has been demonstrated after cooling31323334. However, the mechanisms by which hypothermia produces memory disruption are not well understood.…”