TOBACCO-SMOKE INFLUENCE ON HEART-RATE, BODY-TEMPERATURE, AND LOCOMOTOR-ACTIVITY DAILY RHYTHMS AS ASSESSED BY RADIOTELEMETRY IN RATS

Using radiotelemetry, this study aimed to evaluate the influence of to bacco smoke on heart rate (H), body temperature (T) and locomotor acti vity (A) daily rhythms in rats. The tobacco smoke intoxication was pro duced with a smoking apparatus. H, T, and A data were captured by radi otelemetry. The study was divided into three periods: a 1-week control period (P1), a 1-week stress period (P2), in order to evaluate the st ress induced by the animals' restraint in the smoking apparatus, and a 1-week daily tobacco smoke intoxication period (P3). For P1, P2, and P3, a power spectrum analysis was applied in order to determine the do minant period of rhythmicity. Then, characteristics of the rhythms wer e determined by cosinor analysis. Statistical comparisons were done by ANOVA. Power spectrum analysis showed that neither stress nor tobacco suppressed the daily rhythmicity. Cosinor revealed some modifications : H amplitude was decreased during P2 and P3 with a greater reduction during P3, while T and A amplitudes were decreased during P2 and P3 wi thout difference between P2 and P3. T acrophase was delayed during P2, while A acrophase was delayed during P2 and P3 without any difference between P2 and P3. These perturbations may reflect the effects of str ess and tobacco on the suprachiasmatic nucleus by a dopaminergic mecha nism. (C) 1998 Elsevier Science Inc.