title: Wheel-running and rest activity pattern interaction in two octodontids (Octodon degus, Octodon bridgesi).
abstract: 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.
authors.affiliation: Centro de Neurociencias de Valparaíso, Universidad de Valparaíso. aocampo@med.uchile.cl
authors.forename: Adrián
authors.initials: A
authors.lastname: Ocampo-Garcés
authors.forename: Felipe
authors.initials: F
authors.lastname: Hernández
authors.forename: Wilson
authors.initials: W
authors.lastname: Mena
authors.forename: Adrián G
authors.initials: AG
authors.lastname: Palacios
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D046329:Octodon / Q000502:physiology*; D012146:Rest / Q000502:physiology*; D013045:Species Specificity