Age-related Influence of Hypothyroidism on Caveolins and Nitric Oxide Modulation

pp. 178-184

Abstract

Background. Hypothyroidism and aging influence cardiac and renal nitric oxide (NO) synthesis. Caveolins, which are negative modulators of NO synthase (NOS) activity, are affected by both factors.

Objectives. The aim of this study was to evaluate caveolin (cav) participation in the modulation of renal and cardiac NOS activity in adult hypothyroid animals.

Methods. Euthyroid and hypothyroid [methimazole 0.02% (v/v) in the drinking water during 28 days] male Sprague-Dawley rats were used. Animals were sacrificed to remove the heart and kidneys.

Results. Right atrial NOS activity decreased with aging and hypothyroidism. Cav-1 expression increased with aging and hypothyroidism. Conversely, left ventricular NOS activity increased with aging and hypothyroidism while the expression of both caveolin isoforms decreased in adult and hypothyroid groups. In the renal medulla, hypothyroidism reduced NOS activity in young and raised it in adult animals and cav-1 expression decreased with aging and in hypothyroid young animals. Cav-3 protein levels decreased in adult hypothyroid animals.

Conclusions. Hypothyroidism impacts on NOS activity and on that of its modulators, caveolins, in the cardiovascular and renal systems. Hypothyroidism enhances the effects of aging in both systems.