Conséquences d’une restriction de croissance intra-utérine sur la réactivité aortique chez le rat en fonction de l’âge et du sexe biologique
Background. Vascular tone is regulated by several mechanisms and several exogenous and endogenous stimuli such as circulating hormones and the vasoactive compounds released by the endothelium. Many studies have shown that pre-menopausal women are less likely to develop cardiovascular diseases and that this is due to the protective effects of estrogenic hormones on the cardiovascular system. In addition, some studies have shown that the stiffening of arteries that is associated with aging is different in men and women and that intrauterine growth restriction (IUGR) predisposes to the development of cardiovascular disease in adulthood differently in men and women. We wanted to investigate whether aortic vascular reactivity depends on sex, age and intrauterine environment and whether aortic stiffness is different between males and females. Methods. Thoracic aortic rings from 5-, 12- and 20-week old male and female control and IUGR rats with intact endothelium were mounted in isolated organ baths. The contraction to increasing doses of phenylephrine (PE) with or without L -NAME and the dilatation to increasing doses of carbachol (Cbc) or sodium nitroprusside (SNP) were recorded in order to evaluate the vascular reactivity of the aorta and to compare the different groups. Thoracic aortic rings from male and female rats aged between 13 and 17 weeks were used to assess arterial stiffness. Results. In male rats only, maximal contraction to PE in absence or presence of L-Name increased at the age of 20 weeks in controls and at the age of 12 and 20 weeks in IUGR. In females, maximal contraction in the absence of L-Name was not affected by age or IUGR. However, maximal contraction to PE in the presence of L-Name increased after puberty. The effect of L-Name was stronger in females. Maximal relaxation in response to Cbc was reduced in IUGR groups. However, no difference was observed with SNP and no difference in stiffness was observed between males and females. Conclusion. L-Name experiments suggest that NO has a more important role in females and PE results suggest that males are more responsive to vasoconstrictor stimuli while growing up and this is even more pronounced when they are growth restricted. The difference in maximal contraction between males and females is not due to a difference in arterial stiffness.
Hormones Rat Vascular tone Stiffness Intrauterine growth restriction Nitric oxide Sex Endothelium Age