Examining a novel methodology of long-term low-dose exogenous corticosterone supplementation in neophilic rats

Open Access
Gillon, Jason Thomas
Area of Honors:
Biobehavioral Health
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Sonia Angele Cavigelli, Thesis Supervisor
  • David John Vandenbergh, Honors Advisor
  • corticosterone
  • glucocorticoid
  • Sprague-Dawley
  • behavior
  • stress
  • anxiety
  • neophobic
  • neophilic
  • radioimmunoassay
  • serum
  • fecal
Inhibited rats have baseline and reactivity levels of corticosterone (CORT) approximately 30 ng/mL higher than noninhibited ones (given basal CORT levels of approximately 100 ng/mL), although CORT levels during the recovery period do not mirror this difference. This research established an adapted method of CORT supplementation in drinking water with the purpose of artificially creating this 30 ng/mL CORT increase in noninhibited neophobic rats in order to determine if these rats would become inhibited (neophobic). Typical studies testing the effects of CORT on behavior use large CORT doses on the scale of mg/mL in order to establish the presence of an effect as opposed to the degree of one. We systematically determined that a CORT concentration on the scale of µg/mL was necessary to achieve this slight increase. The CORT supplementation method implemented showed an increase in circulating blood serum, but this increase was variably higher than 30 ng/mL in all three nonadrenalectomized rats assigned to the experimental group. Further refinement of the dosing is necessary for future studies. There were no apparent trends in pre-CORT and post-CORT behavioral tests, suggesting that the slightly higher CORT level seen in neophobic rats is not the causal mechanism of their inhibited behavior.