Neuroendocrine and glial cell remodeling in a hibernating mammal
Thesis (M.S.) University of Alaska Fairbanks, 2021 In most seasonally breeding vertebrates, changes in photoperiod trigger the remodeling of neuroendocrine and glial cells known to be involved in activation of the reproductive axis. We used electron microscopy to determine whether similar remodeling...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/12609 2023-05-15T14:31:30+02:00 Neuroendocrine and glial cell remodeling in a hibernating mammal Duncan, Cassandra Williams, Cory O'Brien, Kristin Christian, Helen 2021-08 http://hdl.handle.net/11122/12609 en_US eng http://hdl.handle.net/11122/12609 Department of Biology and Wildlife Arctic ground squirrel Hibernation Reproduction Neuroglia Paraneurons Photoperiodism Master of Science in Biological Sciences Thesis ms 2021 ftunivalaska 2023-02-23T21:37:57Z Thesis (M.S.) University of Alaska Fairbanks, 2021 In most seasonally breeding vertebrates, changes in photoperiod trigger the remodeling of neuroendocrine and glial cells known to be involved in activation of the reproductive axis. We used electron microscopy to determine whether similar remodeling occurs under conditions of continuous darkness during hibernation in arctic ground squirrels (Urocitellus parryii). Immediately prior to the reproductive season, arctic ground squirrels naturally sequester themselves in a persistently dark hibernacula for 6-8 months where they experience only muted fluctuations in ambient temperature. Hibernation consists of two to three week-long bouts of torpor, during which body temperature and metabolism are depressed, periodically interrupted by short (<24h) interbout arousals where animals become euthermic and metabolism returns to "normal" levels. Although their exact functions are unknown, interbout arousals are generally thought to be associated with homeostatic processes. With the exception of brief dynamic changes during interbout arousals, brain activity and neuroendocrine pathways are generally thought to be relatively static across hibernation. We hypothesized that interbout arousals may allow for cellular ultrastructural remodeling of pars tuberalis thyrotroph cells, hypothalamic tanycytes, and pars distalis gonadotroph cells across hibernation, allowing for animals to activate their reproductive axis in anticipation of the active season. To test this, we sampled brains from arctic ground squirrels during early, mid-, and late hibernation, as well as post hibernation. We found evidence for cellular remodeling and activation of the reproductive axis across hibernation including decreases in neuronal contacts with the hypothalamic basal lamina, increases in the cell area and decreases in granule density of pars distalis gonadotrophs, increases in gonadal mass, and upregulation of steroidogenic genes in gonadal tissue. We hypothesize that the return to euthermy ... Thesis Arctic ground squirrel Arctic Urocitellus parryii Alaska University of Alaska: ScholarWorks@UA Arctic Fairbanks |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
English |
topic |
Arctic ground squirrel Hibernation Reproduction Neuroglia Paraneurons Photoperiodism Master of Science in Biological Sciences |
spellingShingle |
Arctic ground squirrel Hibernation Reproduction Neuroglia Paraneurons Photoperiodism Master of Science in Biological Sciences Duncan, Cassandra Neuroendocrine and glial cell remodeling in a hibernating mammal |
topic_facet |
Arctic ground squirrel Hibernation Reproduction Neuroglia Paraneurons Photoperiodism Master of Science in Biological Sciences |
description |
Thesis (M.S.) University of Alaska Fairbanks, 2021 In most seasonally breeding vertebrates, changes in photoperiod trigger the remodeling of neuroendocrine and glial cells known to be involved in activation of the reproductive axis. We used electron microscopy to determine whether similar remodeling occurs under conditions of continuous darkness during hibernation in arctic ground squirrels (Urocitellus parryii). Immediately prior to the reproductive season, arctic ground squirrels naturally sequester themselves in a persistently dark hibernacula for 6-8 months where they experience only muted fluctuations in ambient temperature. Hibernation consists of two to three week-long bouts of torpor, during which body temperature and metabolism are depressed, periodically interrupted by short (<24h) interbout arousals where animals become euthermic and metabolism returns to "normal" levels. Although their exact functions are unknown, interbout arousals are generally thought to be associated with homeostatic processes. With the exception of brief dynamic changes during interbout arousals, brain activity and neuroendocrine pathways are generally thought to be relatively static across hibernation. We hypothesized that interbout arousals may allow for cellular ultrastructural remodeling of pars tuberalis thyrotroph cells, hypothalamic tanycytes, and pars distalis gonadotroph cells across hibernation, allowing for animals to activate their reproductive axis in anticipation of the active season. To test this, we sampled brains from arctic ground squirrels during early, mid-, and late hibernation, as well as post hibernation. We found evidence for cellular remodeling and activation of the reproductive axis across hibernation including decreases in neuronal contacts with the hypothalamic basal lamina, increases in the cell area and decreases in granule density of pars distalis gonadotrophs, increases in gonadal mass, and upregulation of steroidogenic genes in gonadal tissue. We hypothesize that the return to euthermy ... |
author2 |
Williams, Cory O'Brien, Kristin Christian, Helen |
format |
Thesis |
author |
Duncan, Cassandra |
author_facet |
Duncan, Cassandra |
author_sort |
Duncan, Cassandra |
title |
Neuroendocrine and glial cell remodeling in a hibernating mammal |
title_short |
Neuroendocrine and glial cell remodeling in a hibernating mammal |
title_full |
Neuroendocrine and glial cell remodeling in a hibernating mammal |
title_fullStr |
Neuroendocrine and glial cell remodeling in a hibernating mammal |
title_full_unstemmed |
Neuroendocrine and glial cell remodeling in a hibernating mammal |
title_sort |
neuroendocrine and glial cell remodeling in a hibernating mammal |
publishDate |
2021 |
url |
http://hdl.handle.net/11122/12609 |
geographic |
Arctic Fairbanks |
geographic_facet |
Arctic Fairbanks |
genre |
Arctic ground squirrel Arctic Urocitellus parryii Alaska |
genre_facet |
Arctic ground squirrel Arctic Urocitellus parryii Alaska |
op_relation |
http://hdl.handle.net/11122/12609 Department of Biology and Wildlife |
_version_ |
1766305114462617600 |