Time of day differences in IL1β and TNFα mRNA levels in specific regions of the rat brain

Interleukin-1beta (IL1beta) and tumor necrosis factor-alpha (TNFalpha) are involved in several physiological functions regulated by brain. The current studies were performed to determine whether a diurnal rhythm of IL1beta and TNFalpha mRNAs, determined by real time RT-PCR, existed in specific brain regions linked to the functions of these cytokines. Rats were sacrificed 2 It after light onset (AM) and 1 h prior to dark onset (PM). IL1beta mRNA levels in the AM were significantly higher than those obtained from rats sacrificed in the PM in the prefrontal cortex, parietal cortex, amygdala/piriform cortex, ventral hippocampus, hypothalamus, nucleus tractus solitarius, and nucleus accumbens, but not in the dorsal hippocampus. Time-of-day differences in TNFalpha mRNA levels were observed in all these brain regions. These results Support the hypothesis that TNFalpha and IL1beta have physiological roles within the brain. (C) 2003 Elsevier Ireland Ltd. All rights reserved.