The proposed work investigates the relative roles of body temperature and endogenous circannual rhythms in controlling reproductive maturation in hibernating arctic ground squirrels. Specific goals include: (1) assessing the temperature sensitivity of reproductive hormone secretion in hypothermic and active animals, (2) determining the role of periodic arousals in testis growth, (3) characterizing secretion and metabolic clearance rate of gonadotropins and testosterone in animals naturally at body temperatures of 2 degrees Centigrade and 37 degrees Centigrade, (4) describing the natural pattern of testis growth and development over the hibernation season and testing the influence of elevated temperature on the timing of this pattern, (5) assessing the thermoregulatory options open to hibernating animals to avoid temperature constraints on endocrine function, and (6) determining the importance of sustained normothermic body temperature for sperm viability. These experiments should elucidate adaptations for function of basic regulatory mechanisms controlling reproduction and fertility under extremes of body temperature; they should help determine the scope of endocrine responsiveness in mammals, especially the temperature limit below which hormone secretion or turnover cannot occur.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
3R01HD023383-03S1
Application #
3323543
Study Section
Reproductive Endocrinology Study Section (REN)
Project Start
1987-07-01
Project End
1990-12-31
Budget Start
1990-07-01
Budget End
1990-12-31
Support Year
3
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Alaska Fairbanks
Department
Type
Organized Research Units
DUNS #
615245164
City
Fairbanks
State
AK
Country
United States
Zip Code
99775