ECE2019 Poster Presentations Interdisciplinary Endocrinology 2 (37 abstracts)
Ultrastructural changes of neuroendocrine and endocrine responding cells associated with reproductive timing in a hibernating mammal
Cassandra Duncan 1 , Helen Christian 2 , Helen Chmura 1 , Charles Buck 3 , Brian Barnes 1 , Andrew Loudon 4 & Cory Williams 1
1University of Alaska Fairbanks, Fairbanks, USA; 2University of Oxford, Oxford, United Kingdom; 3Northern Arizona University, Flagstaff, USA; 4University of Manchester, Manchester, United Kingdom.
Reproductive timing strongly influences the fitness of the individual. While most vertebrates rely on photoperiodic changes to induce seasonal reproduction, the arctic ground squirrel (AGS) naturally undergoes reproductive maturation in a photoperiod-independent manner. In addition, males spontaneously activate their reproductive axis during hibernation, but the timing of reproduction is sensitive to external cues. We are using electron microscopy to examine, define, and measure ultrastructural remodeling in pars tuberalis (PT) thyrotroph cells, hypothalamic tanycytes, and pars distalis (PD) gonadotroph cells, as the AGS transitions from hibernation to the reproductive season. We are also quantifying how the morphology of these cells correspond with measures of reproductive axis outputs, including changes in steroidogenic gene expression in gonads, gonadal development and maturation, and plasma sex steroid concentrations. Finally, we are examining the mechanisms that underly plasticity in hibernation phenology and examining whether hypothalamic and PD activity can become dissociated from the PT signaling pathway by assessing cellular remodeling in males placed in a 30°C room during mid-hibernation, which induces early reproductive onset. We hypothesize that changes in PT morphology underlie the termination of torpor and initiation of reproduction in a photoperiod-independent manner. This basic system-level investigation of reproductive control mechanisms may inform researchers on how cellular ultrastructure influences connections between neuroendocrine circuits and the role this plays in directing activation of puberty onset, without photic cues.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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