4 research outputs found
The influence of gender on the association between hyperinsulinemia/insulin resistance and hypertension
The primary objective of this study was to examine the relationship between
hyperinsulinemia / insulin resistance and hypertension in female rats. A link between these
two conditions has been well established in studies employing male animal models as well as
in human studies, however, it has not been possible to discern what role gender plays in this
relationship, if any, based on these previous reports. To investigate the effect of gender on
the association between hyperinsulinemia / insulin resistance, two different
hyperinsulinemic, hypertensive rat models were used; the fructose fed hypertensive rat
(FHR) and a chronically insulin treated rat. In the first set of experiments using fructose fed
animals, we found that fructose causes hyperinsulinemia, insulin resistance and hypertension
in males, but does not affect metabolism or blood pressure at all in females. However in a
separate experiment, female rats that had been ovariectomized did develop insulin resistance
and hypertension, indicating that normal levels of ovarian sex hormones are involved in
protecting female rats against the effects of a fructose diet. In a second set of blood pressure
experiments, we employed a chronic exogenous insulin treatment to attempt to create a state
of insulin resistance in females. In this study, we observed that exogenous hyperinsulinemia
causes insulin resistance in both male and female rats, however, this occurs to a greater
degree in males. Furthermore, hyperinsulinemia and insulin resistance were only associated
with hypertension in male rats.
Several mechanisms have been proposed to play a role in the development of hypertension
associated with hyperinsulinemia and insulin resistance. A secondary objective of this thesis
was to identify potential mechanisms that might explain any gender differences observed. To
this aim, we focused on vascular function. We examined the vascular effects of insulin and
found that it tends to act more as a vasoconstrictor in female rats rather than a vasodilator, as
we had previously demonstrated in males. We also demonstrated that there is a significant
gender difference in the effect of U46619, a synthetic thromboxane analogue, which may be
related to gender differences in the development of hypertension associated with
hyperinsulinemia and insulin resistance.Medicine, Faculty ofAnesthesiology, Pharmacology and Therapeutics, Department ofGraduat