Key result
Streptozocin-induced diabetes in rats caused progressive changes in vascular reactivity, with early changes likely mediated by hypothyroidism and later changes by other factors like hyperglycemia.
Why the study?
How does vascular reactivity in the mesenteric vascular bed change in streptozocin-induced diabetic rats compared to hypothyroid rats?
How does vascular reactivity in the mesenteric vascular bed change in streptozocin-induced diabetic rats compared to hypothyroid rats?
Early vascular reactivity changes in diabetic rats may be mediated by hypothyroidism, while later changes and adrenergic neuropathy are likely induced by other factors like hyperglycemia and hypoinsulinemia.
Does not support clinical extrapolation from rat models; leaves open hypothyroidism's role in early human diabetic vasculopathy.
The responsiveness to vasoactive agents in the perfused mesenteric vascular bed of streptozocin-induced diabetic rats was examined and compared with that of propylthiouracil-induced hypothyroid rats. Diabetic rats at 4 and 8 weeks after the induction of diabetes showed a significant decrease in isoproterenol-induced vasodilatation. In addition, the contractile responses to norepinephrine and 5-hydroxytryptamine and the vasodilative response to acetylcholine were significantly decreased in 12-week-diabetic rats. The contractile response to nerve stimulation was markedly decreased at 8 and 12 weeks. On the other hand, hypothyroid rats showed a decreased response to isoproterenol, but they did not show any change in the response to nerve stimulation. A decrease in plasma thyroid hormone levels in diabetic rats at any time period was similar in extent to that in hypothyroid rats. The data indicate that the progressive changes in vascular reactivity in diabetic rats may be divided into two stages. In the early stage, the altered reactivity of vasculature is likely to be mediated by hypothyroidism, whereas in the later stage, it is induced by other factors, e.g. hyperglycemia and hypoinsulinemia. Adrenergic neuropathy is not caused by hypothyroidism.
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Takiguchi et al. (2008) studied Diabetes and Hypothyroidism. Streptozocin-induced diabetes vs. Propylthiouracil-induced hypothyroidism was evaluated on Vascular reactivity to vasoactive agents and nerve stimulation. Streptozocin-induced diabetes in rats caused progressive changes in vascular reactivity, with early changes likely mediated by hypothyroidism and later changes by other factors like hyperglycemia.
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