Sex hormone replacement therapy reverses decreased venous distensibility in pharmacologically ovariectomized rats.
OBJECTIVE
To test the effect of female sex hormone depletion and replacement on the distensibility and geometry of the saphenous vein in female rats.


METHODS
Twenty Sprague-Dawley rats were pharmacologically ovariectomized by triptorelin. Ten of these animals received combined hormone replacement with estradiol and medroxyprogesterone acetate. The rest were given vehicle. Ten animals kept parallel without pharmacological ovariectomy served as controls. After 3 months of treatment, a segment of the saphenous vein was dissected. Pressure-diameter curves were recorded in relaxed, contracted, and control states using a microangiograph.


RESULTS
Pharmacological ovariectomy lowered venous wall distensibility measured in contraction (at P=8 mm Hg: 4.41+/-1.21*10(-3) m2/N vs. control: 0.79+/-0.14*10(-3) m2/N; p < 0.05). Hormone replacement partially restored this value (1.8+/-0.49*10(-3) m2/N). No alterations in distensibility were found in the relaxed state. After adjusting for body weight, we found that pharmacological ovariectomy lowered venous inner radius significantly compared with control (p < 0.05), whereas hormone replacement increased it compared with pharmacological ovariectomy (p < 0.05) and more significantly compared with control (p < 0.01).


CONCLUSIONS
Sex hormone depletion induces significant alterations in venous distensibility, presumably by inducing initial remodeling of the venous wall. Hormone dependency of distensibility differed in relaxed and contracted states of the vein, so some alterations of contractile elements of the wall may be hypothesized. Lower distensibility of the venous wall found after pharmacological ovariectomy could be part of the mechanism of predisposition for postmenopausal hypertension. This can be reversed by female sex hormone replacement.
Várbíró
S
S
Experimental Research Department-2nd Institute of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary.
Nádasy
G L
GL
Monos
E
E
Acs
N
N
Vajo
Z
Z
Székács
B
B
D000818:Animals; D004195:Disease Models, Animal; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D020249:Hormone Replacement Therapy; D007273:Injections, Intramuscular; D017258:Medroxyprogesterone Acetate / Q000008:administration & dosage / Q000494:pharmacology*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012501:Saphenous Vein / Q000187:drug effects* / Q000502:physiology*; D017329:Triptorelin Pamoate
D017329:Triptorelin Pamoate; D004958:Estradiol; D017258:Medroxyprogesterone Acetate