Determination of denning bear isolate and its effects on non-denning guinea pigs
Miers, Patricia Govoni
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https://hdl.handle.net/2142/20155
Description
Title
Determination of denning bear isolate and its effects on non-denning guinea pigs
Author(s)
Miers, Patricia Govoni
Issue Date
1994
Department of Study
Nutritional Sciences
Discipline
Nutritional Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Health Sciences, Pharmacology
Biology, Animal Physiology
Health Sciences, Nutrition
Language
eng
Abstract
The North American Black Bear (Ursus americanus) fasts for five months in the winter. While maintaining body temperature at 35$\sp\circ$C, the bear requires no food or water and does not urinate or defecate. Anabolic functions such as protein synthesis and bone remodeling continue. Female bears complete gestation, parturition and lactation.
Serum and urine samples collected from summer active and winter denning black bears were compared. A naturally occurring substance (MNC) was associated with the winter fast. MNC was chemically identified, purified and partially characterized. MNC is a hydrophilic, UV-active, ninhydrin positive, heterocyclic moiety of low molecular weight. Its structure is similar to indoles and phenols.
Isolates of deproteinated urine from winter denning black bears (DBI) containing MNC were injected into active guinea pigs that do not den. Heart rate, body temperature, and respiration were monitored before and after DBI injections. Tranquility, food and water intake, urine excretion and urinary urea and creatinine content were measured.
Urine DBI was purified into three fractions: MNC, BHB, and (DBI without (BHB and MNC)). Fraction BHB contained beta-hydroxybutyrate (BHB) in addition to other components. Whole urine DBI induced the largest changes with marked reductions in heart rate, body temperature, food and water intake and urine excretion. Urea recycling increased and tranquility was noted. However, the purified fractions of MNC+BHB were most potent by weight in producing the black bear denning response. Guinea pigs receiving MNC+BHB had reduced heart rates, temperatures, and respirations as well as increased tranquility lasting up to 95 minutes post injection. Urinary excretion of urea remained low for at least 4 days post injection. MNC+BHB did not influence food or water consumption. No adverse effects were detected in guinea pigs injected with MNC+BHB.
Serum and urine from 45 healthy adult humans were assayed for MNC before and after a 20 hour food restricted fast. MNC was not detected while BHB levels were significantly higher post fast. Serum urea concentrations decreased in the fasted humans while urine urea concentrations remained constant.
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