Modulations of Hypoxic-Induced Changes in Body Temperature and Activity in Cohorts of Rats by an Affiliate Neural Network

We hypothesized that chronic hypoxia's disruption of the regulation of body temperature (T_b), activity (L_a) and their respective circadian oscillations in cohorts of rats, caged separately from each other, differs significantly between two cohorts, one in constant light (LL) and the other in constant dark (DD) at the environmental temperature of 21°C. The LL cohort, and similarly for the DD cohort, each cohort was exposed to normoxia (days 1-3), followed by hypoxia (days 4-6) and finally returned to normoxia (days 7-9). Circadian oscillations of T_b were abolished in LL during hypoxia and post-hypoxia and in DD markedly depressed only during hypoxia. In LL, oxygen level and its interaction with the light level were significantly different (P ＜ 0.001 and P = 0.01, respectively) but not for light level alone (P = 0.96). In DD, oxygen level and its interaction with the light level were significantly different (P ＜ 0.001 and P = 0.01) but not significantly different for light level alone (P = 0.02). The overall accepted level of significance was P ≤ 0.01. We postulate that a corticolimbic neural network in LL and DD cohorts modulates the hypoxic-induced changes in the T_b and L_a and depends on communication of olfactory and ultrasonic cues and detection of light present or absent.