Submitted on January 14, 2008
Accepted on March 17, 2008
Effects of Thyroidectomy, T4 and DITPA Replacement on Brain Blood Vessel Density in Adult Rats
Evelyn Heymann Schlenker1*, Megan Hora1, Yingheng Liu2, Rebecca A Redetzke2, Eugene Morkin3, and A. Martin Geredes4
1 Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, Vermillion, South Dakota, United States
2 Cardiovascular Research Center, Sanford Research, University of South Dakota, Sioux Falls, South Dakota, United States
3 Sarver Heat Center, University of Arizona, Tucson, Arizona, United States
4 Cardiovascular Research Center, Sanford Research, University of South Dakota, Sioux Falls, South Dakota, United States; Sioux Falls, South Dakota, United States
* To whom correspondence should be addressed. E-mail: Evelyn.Schlenker{at}usd.edu.
In hypothyroid patients altered microvascular structure and function may affect mood and cognitive function. We hypothesized that adult male hypothyroid (H) rats will have significantly lower forebrain blood vessel densities (BVD) than euthyroid (E) rats, and that treatment with DITPA (D) - (a thyroid hormone analogue) or T4 (T) will normalize BVD's. The E group received no thyroidectomy or treatment. The other three groups received thyroidectomies and pellets. The H group received a placebo pellet, the D group received an 80mg DITPA-containing pellet, and the T group received a 5.2mg T4 slow release pellet for 6 weeks. Body weights (BW), cardiac function, and body temperatures (BT) were measured. A monoclonal anti-platelet endothelial cell adhesion antibody was used to visualize blood vessels. The E group averaged BW of 548 ±54g, while the H group averaged BW of 332 ± 19g (p-value< 0.001). Relative to the E group, the D-treated group was significantly lighter (p-value < 0.05) while the T-treated group was comparable in BW to the E group. The same trends were seen with BT and cardiac function with the largest difference between the E and H groups. BVD in the E group was 147 ±12 blood vessels per mm2, and in H group 69 ± 5 blood vessels per mm2 (P=0.013) , but similar among the E, D, and T groups. These results show that hypothyroidism decreased BVD in adult rat forebrain regions. Moreover, DITPA and T4 were efficacious in preventing effects of hypothyroidism on cardiac function and BVD.
