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Estrous Cyclicity of Mice During Simulated Weightlessness
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Author and Affiliation:
Moyer, Eric(Blue Marble Space, Seattle, WA, United States)
Talyansky, Yuli(Blue Marble Space, Seattle, WA, United States)
Scott, Ryan(Wyle Labs., Inc., Moffett Field, CA, United States)
Tash, Joseph(Kansas Univ. Medical Center Research Inst., Kansas City, KS, United States)
Christenson, Lane(Kansas Univ. Medical Center Research Inst., Kansas City, KS, United States)
Alwood, Joshua(NASA Ames Research Center, Moffett Field, CA, United States)
Ronca, April(NASA Ames Research Center, Moffett Field, CA, United States)
Abstract: Hindlimb unloading (HU) is a rodent model system used to simulate weightlessness experienced in space. However, some effects of this approach on rodent physiology are under-studied, specifically the effects on ovarian estrogen production which drives the estrous cycle. To resolve this deficiency, we conducted a ground-based validation study using the HU model, while monitoring estrous cycles in 16-weeks-old female C57BL6 mice. Animals were exposed to HU for 12 days following a 3 day HU cage acclimation period, and estrous cycling was analyzed in HU animals (n22), normally loaded HU Cage Pair-Fed controls (CPF; n22), and Vivarium controls fed ad libitum (VIV; n10). Pair feeding was used to control for potential nutritional deficits on ovarian function. Vaginal cells were sampled daily in all mice via saline lavage. Cells were dried and stained with crystal violet, and the smears evaluated using established vaginal cytology techniques by two individuals blinded to the animal treatment group. Estrous cyclicity was disrupted in nearly all HU and CPF mice, while those maintained in VIV had an average normal cycle length of 4.8 0.5 days, with all stages in the cycle visibly observed. CPF and HU animals arrested in the diestrous phase, which precedes the pre-ovulatory estrogen surge. Additionally, infection-like symptoms characterized by vaginal discharge and swelling arose in several HU animals, which we suspect was due to an inability of these mice to properly groom themselves, andor due to the change in the gravity vector relative to the vaginal opening, which prevented drainage of the lavage solution. Pair-feeding resulted in similar weight gains of HU and CPF (1.5 vs 3.0, respectively). The current results indicate that pair-feeding controlled weight gain and that the HU cage alone influenced estrous cyclicity. Thus, longer acclimation needs to be tested to determine if and when normal estrous cycling resumes in non-loaded mice in HU cages prior to HU testing. Future studies might also examine whether modifications to the vaginal lavage procedure might prevent the onset of the infection-like symptoms, and allow estrous cyclicity to be measured in this model system.
Publication Date: Oct 25, 2017
Document ID:
20170011558
(Acquired Dec 18, 2017)
Subject Category: LIFE SCIENCES (GENERAL)
Report/Patent Number: ARC-E-DAA-TN48069
Document Type: Oral/Visual Presentation
Publication Information: SEE 20170010367
Meeting Information: 33rd Annual Meeting American Society for Gravitational and Space Research; 25-28 Oct. 2017; Seattle, WA; United States
Meeting Sponsor: American Society for Gravitational and Space Research; Bristow, VA, United States
Contract/Grant/Task Num: NNA14AB82C; NNX15AG98A; NNX15AB48G
Financial Sponsor: NASA Ames Research Center; Moffett Field, CA, United States
Organization Source: NASA Ames Research Center; Moffett Field, CA, United States
Description: 10p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Use by or on behalf of the U.S. Government permitted
NASA Terms: CYTOLOGY; ESTROGENS; GRAVITATION; HINDLIMB SUSPENSION; MICE; WEIGHTLESSNESS SIMULATION; FEMALES; RODENTS; SIGNS AND SYMPTOMS; WEIGHTLESSNESS
Other Descriptors: MOUSE; HINDLIMB UNLOADING; FERTILIT
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