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Effects of Spring Warming on Seasonal Neuroendocrinology and Activation of the Reproductive Axis in Hibernating Arctic Ground Squirrels.
Chmura, Helen E; Duncan, Cassandra; Saer, Ben; Moore, Jeanette T; Barnes, Brian M; Buck, C Loren; Loudon, Andrew S I; Williams, Cory T.
Afiliación
  • Chmura HE; Institute of Arctic Biology, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775, USA.
  • Duncan C; Rocky Mountain Research Station, United States Forest Service, 800 E. Beckwith Missoula, MT 59801, USA.
  • Saer B; Department of Biology and Wildlife, University of Alaska Fairbanks, 2090 Koyukuk Drive, Fairbanks, AK 99775, USA.
  • Moore JT; Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT , UK.
  • Barnes BM; Institute of Arctic Biology, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775, USA.
  • Buck CL; Institute of Arctic Biology, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775, USA.
  • Loudon ASI; Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011, USA.
  • Williams CT; Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT , UK.
Integr Comp Biol ; 62(4): 1012-1021, 2022 10 29.
Article en En | MEDLINE | ID: mdl-35790133
Many animals adjust the timing of seasonal events, such as reproduction, molt, migration, and hibernation, in response to interannual variation and directional climate-driven changes in temperature. However, the mechanisms by which temperature influences seasonal timing are relatively under-explored. Seasonal timing involves retrograde signaling in which thyrotropin (TSH) in the pars tuberalis (PT) alters expression of thyroid hormone (TH) deiodinases (Dio2/Dio3) in tanycyte cells lining the third ventricle of the hypothalamus. This, in turn, affects the availability of triiodothyronine (T3) within the mediobasal hypothalamus-increased hypothalamic T3 restores a summer phenotype and activates the reproductive axis in long-day breeders. Recently, we showed that retrograde TH signaling is activated during late hibernation in arctic ground squirrels (Urocitellus parryii) held in constant darkness and constant ambient temperature. Sensitivity of seasonal pathways to nonphotic cues, such as temperature, is likely particularly important to hibernating species that are sequestered in hibernacula during spring. To address this issue, we exposed captive arctic ground squirrels of both sexes to an ecologically relevant increase in ambient temperature (from -6 to -1°C) late in hibernation and examined the effects of warming on the seasonal retrograde TSH/Dio/T3 signaling pathway, as well as downstream elements of the reproductive axis. We found that warmed males tended to have higher PT TSHß expression and significantly heavier testis mass whereas the TSH/Dio/T3 signaling pathway was unaffected by warming in females, although warmed females exhibited a slight decrease in ovarian mass. Our findings suggest that temperature could have different effects on gonadal growth in male and female arctic ground squirrels, which could lead to mismatched timing in response to rapid climate change.
Asunto(s)

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Sciuridae / Neuroendocrinología Límite: Animals Idioma: En Revista: Integr Comp Biol Año: 2022 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Sciuridae / Neuroendocrinología Límite: Animals Idioma: En Revista: Integr Comp Biol Año: 2022 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido