Effects of photoperiod on testicular functions in male sprague-dawley rats

  • L.A Olayaki
  • A.O Soladoye
  • T.M Salman
  • B Joraiah
Keywords: Photoperiod, Sperm motility, Sperm viability, Sperm counts, Testicular weight.


Variation in reproductive status in response to photoperiods has been observed in laboratory rats. We investigated the effects of photoperiod on testicular activity in Sprague-Dawley rats (Rattus norvigicus) maintained in experimental photoperiodic condition. Twenty four adult male rats weighing 170±10g were conditioned to different lighting conditions of Light/Dark (LD) Cycle for 6 weeks. Group 1, Control group (LD12:12, light on from 07:00hr to 19:00hr). Group 2, Short Photoperiod group (LD 8:16hr, light on from 09:00hr to 17:00hr). Group 3, Long Photoperiod group (LD 16:8hr, light on from 05:00hr to 21:00hr). A significant influence of different lighting conditions on the testicular parameters was observed. Short photoperiod showed a suppressing effect (P<0.001) on testicular weight, sperm motility sperm viability and sperm counts, while long photoperiod had an inducing, though insignificant, effect on the measured parameters. The results confirmed that Sprague- Dawley rats are photoresponsive and changes in the photoperiod could influence their reproductive functions.

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eISSN: 0794-859X