A Model of early vitamin deficiency in a hibernator, the 13-lined ground squirrel
File(s)
Date
2016-08-23Author
Sprenger, Ryan J.
Advisor(s)
Kurtz, Courtney
Metadata
Show full item recordAbstract
Hibernators, such as the 13-lined ground squirrel (Ictidomys tridecemlineatus), undergo
dramatic changes in adipose tissue mass during their circannual cycle. Retinoic acid
(RA), the biologically active derivative of vitamin A, plays key roles in the development
and growth of adipose tissue. We developed a model of early vitamin A deficiency in
juvenile ground squirrels to determine RA’s effects on the ability to adequately build
adipose mass prior to the first season of hibernation. Deficient squirrels (VAD) were
maintained on the diet until 8 weeks of age when severe symptoms of hypovitaminosis
were observed, including stunted growth and limb weakness. Liver retinoid analysis
showed that these animals had essentially no retinoid stores. Even when placed on a
normal diet, the VAD squirrels never reached the retinoid stores of controls. Control
retinoid stores were high compared to other rodents, but in the normal range for the
species. Serum retinol binding protein (RBP) was not affected by diet, although
decreased levels were found in torpid hibernators. Early deficiency was associated with
decreased mass of white (WAT) and brown (BAT) adipose tissue depots, decreased
expression of resistin, altered seasonal expression of the RXR-β retinoid receptor and
increased expression of BAT uncoupling protein. Our results suggest that ground
squirrels require high levels of retinoids for normal function and are especially
susceptible to deficiency as it affects the seasonal accumulation of adipose tissue.
Subject
Wildlife Management
Ground squirrels
Permanent Link
http://digital.library.wisc.edu/1793/75217Description
A Thesis Submitted In Partial Fulfillment of the Requirements For the Degree of Master of Science - Biology