Wheel-running and rest activity pattern interaction in two octodontids (Octodon degus, Octodon bridgesi)

• ADRIÁN OCAMPO-GARCÉS ^[1] ; FELIPE HERNÁNDEZ ^[2] ; WILSON MENA ^[1] ; ADRIÁN G PALACIOS ^[1]
  1. [1] Universidad de Valparaíso

     Universidad de Valparaíso

     Valparaíso, Chile

     
  2. [2] Universidad de Chile

     Universidad de Chile

     Santiago, Chile

     
• Localización: Biological Research, ISSN-e 0717-6287, ISSN 0716-9760, Vol. 38, Nº. 2-3, 2005, págs. 299-305
• Idioma: inglés
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• Resumen

  • Wheel-running and other non-photic stimuli influence the rest-activity pattern of diurnal and nocturnal mammals. A day to night inversion of phase preference of activity was described among Octodon degus, when exposed to ad-libitum wheel running. We have studied the rest-activity pattern response in presence of ad libitum wheel-running in wild-captured male individuals from two species of genus Octodon: O. degus (n=9, crepuscular-diurnal) and O. bridgesi (n=3, nocturnal). After two months of habituation to laboratory conditions, recordings were performed in isolation chambers under a 12:12 light-dark schedule with or without access to a running wheel. Actograms were constructed from data obtained by an automated acquisition system. O. bridgesi were also recorded under constant darkness, with or without access to wheel-running. Entrained to the light-dark schedule, a crepuscular pattern of activity was evident for O. degus, whereas O. bridgesi displayed a robust nocturnal chronotype. The activity of O. degus observed during the dark phase was enhanced when wheel-running was allowed. No significant change in phase preference was observed for O. bridgesi when wheel-running was allowed. A lengthening of endogenous period was observed in O. bridgesi after wheel-running exposure under constant darkness. Nocturnal and diurnal octodontids exhibit different masking responses to wheel-running.