Effect of photoperiod on some haematological indices in rats

Abstract

The study was designed to investigate the effects of photoperiod on some haematological indices in male Sprague-Dawley rats. Twenty four adult male rats were divided into four groups of six rats per group. The control group was maintained under natural light condition 12hours of light and 12hours of darkness (12L : 12D). The short photoperiod (SP) was maintained under 8hours of light and 16hours of darkness (8L : 16D), the long photoperiod (LP), was maintained under 16 hours of light and 8hours of darkness (8L : 16D), the long photoperiod (LP), was maintained under 16 hours of light and 8hours of darkness (16L : 8D), the rats in long photoperiod with tryptohan group was kept as LP, but were administered 100mg/kg body weight of L-tryptophan daily. After 6 weeks, the haematological indices were determined in the rats. The results show an increase in haematological indices under SP tryptophan significantly reduced the haematological indices except packed cell volume (PCV). Furthermore, white blood cell count (WBC) differential showed a lymphocytic leukocytosis in the SP group. Therefore, it is concluded that SP enhances haematological indices in Sprague-Dawley rats. Nigerian Journal of Health and Biomedical Sciences Vol. 7 (1) 2008 pp. 11-14