Sleep-related movement disorder symptoms in SHR are attenuated by physical exercise and an angiotensin-converting enzyme inhibitor

Abstract

The relationship between hypertension and sleep-related movement disorders has been hypothesized for humans, but the causes and mechanisms have not been elucidated. We investigated whether an alteration in blood pressure (BP) induced by physical exercise and/or an angiotensin-converting enzyme inhibitor (enalapril) could affect locomotor activity in spontaneously hypertensive rats, with emphasis on the dopaminergic system. We used SHR and normotensive Wistar rats distributed into 4 groups for each strain: control, physical exercise, enalapril and physical exercise+enalapril. Physical exercise was performed on a treadmill, and enalapril was administered by gavage, both for 8weeks. During this period, locomotor activity was evaluated in an open field test, and BP was evaluated by tail plethysmography. Dopaminergic receptors, dopamine transporter and tyrosine hydroxylase levels at the striatum were evaluated by Western blotting. The control group of spontaneously hypertensive rats showed higher BP, increased activity in the open field test and lower levels of D2 receptors and tyrosine hydroxylase compared with all other groups throughout the experimental period. In general, physical exercise and enalapril attenuated these alterations. This study suggested the existence of comorbidity between hypertension and sleep-related movement disorders in spontaneously hypertensive rats. Physical exercise and enalapril conferred protection for both hypertension and the observed behavioral changes. In addition, these treatments led to changes in dopaminergic signaling in the striatal region (i.e., D2 receptor, TH and DAT).

Keywords: Dopamine; Enalapril; Physical exercise; Restless legs syndrome; Spontaneously hypertensive rats.