scholarly journals Cardiac concentric remodelling induced by non-aromatizable (dihydro-)testosterone is antagonized by oestradiol in ovariectomized rats

2006 ◽  
Vol 189 (3) ◽  
pp. 485-491 ◽  
Author(s):  
Å Tivesten ◽  
E Bollano ◽  
H C Nyström ◽  
C Alexanderson ◽  
G Bergström ◽  
...  
Keyword(s):  
Growth Factor ◽  
Wall Thickness ◽  
Cardiovascular Effects ◽  
Left Ventricular ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Heart Weight ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Growth Factor I

Previous studies on the cardiovascular effects of androgens in females, most of them using testosterone treatment, have yielded conflicting results. Testosterone is metabolized into oestradiol (E2) and dihydrotestosterone (DHT) within cardiovascular tissues. The aim of the present study was to explore the cardiovascular effects exerted by E2 and the non-aromatizable androgen DHT and to study possible interactions between these in female rats. Ovariectomized rats were treated with DHT, E2, or DHT+E2 for 6 weeks. DHT increased left-ventricular posterior wall thickness, assessed by echocardiography, whereas left-ventricular dimension, as well as total heart weight and calculated left-ventricular mass, were unchanged. DHT also increased the levels of insulin-like growth factor-I mRNA in the left ventricle. E2 abolished the effect of DHT on left-ventricular remodelling and insulin-like growth factor-I mRNA when the two treatments were given in combination. E2 also reduced androgen receptor mRNA levels in the heart. Neither E2 nor DHT changed blood pressure measured by telemetry. In conclusion, treatment with the endogenous non-aromatizable androgen DHT causes cardiac concentric remodelling in ovariectomized rats, possibly mediated by increased local levels of insulin-like growth factor-I. The effect of DHT on cardiac wall thickness was antagonized by E2, possibly through downregulation of cardiac androgen receptors. These mechanisms may be of importance for the concentric left-ventricular geometric pattern developing in women after menopause.

Long-term reductions in GH, insulin-like growth factor-I and body weight gain in rats treated neonatally with antibodies to rat GH

1990 ◽  
Vol 124 (3) ◽  
pp. 381-386 ◽  
Author(s):  
M. J. Gardner ◽  
D. J. Flint
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Growth Factor ◽  
Body Weight Gain ◽  
Female Rats ◽  
Serum Prolactin ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Growth Factor I

ABSTRACT Treatment of neonatal rats on days 2–5 with antibodies against rat GH (rGH) markedly reduced body weight gain and serum concentrations of insulin-like growth factor-I for 6–8 weeks in both females and males, after which weight gain normalized without evidence of catch-up growth. There were no significant effects on serum prolactin, tri-iodothyronine or corticosterone. Testis and ovarian weights were reduced, although only in proportion to body size. In females, but not males, the treated rats, though lighter, had increased fat deposition in the parametrial depot. Pituitary weight was considerably reduced over 100 days later, as was the pituitary content of GH, but not prolactin. The response to GH-releasing factor of both male and female rats was also greatly reduced at this time. Taken together with the fact that these rGH antibodies can bind directly to somatotrophs, we propose that the long-term effects of the antibodies are induced by specific somatotroph destruction. Journal of Endocrinology (1990) 124, 381–386

Stimulation of trabecular bone formation by insulin-like growth factor I in adult ovariectomized rats

1994 ◽  
Vol 267 (1) ◽  
pp. E1-E6 ◽  
Author(s):  
K. Mueller ◽  
R. Cortesi ◽  
D. Modrowski ◽  
P. J. Marie
Keyword(s):  
Growth Factor ◽  
Bone Formation ◽  
Trabecular Bone ◽  
Ovariectomized Rats ◽  
Maximal Effect ◽  
Insulin Like Growth Factor ◽  
Bone Formation Rate ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

Although in vitro experiments indicate that insulin-like growth factor I (IGF-I) is an anabolic hormone in bone cell metabolism, the effects of IGF-I in vivo on bone formation are unclear. We thus investigated whether IGF-I is able to stimulate bone formation in adult rats with established osteopenia induced by ovariectomy (OVX). IGF-I was administered at daily doses of 0.05, 0.2, and 0.8 mg/kg for 3 wk. OVX induced a marked osteopenia in femur and tibia. Administration of IGF-I increased trabecular bone mass with a maximal effect at 0.2 mg/kg. The same dose stimulated bone formation, as revealed by an increase in osteoid surface, osteoblast surface, triple tetracycline-labeled surface, and bone formation rate. The mineral apposition rate was equally stimulated at all doses. At the highest dose, IGF-I increased osteoclast surface and osteoclast number. These data indicate that, in the adult OVX rat, IGF-I stimulates bone formation and increases trabecular bone volume at medium doses and enhances the histological indexes of bone resorption at high doses.

scholarly journals Acute Cardiovascular Effects of Insulin-Like Growth Factor I in Patients with Chronic Heart Failure1

1998 ◽  
Vol 83 (9) ◽  
pp. 3177-3183 ◽  
Author(s):  
Marc Y. Donath ◽  
Gabor Sütsch ◽  
Xia-Wei Yan ◽  
Bruno Piva ◽  
Hans-Peter Brunner ◽  
...  
Keyword(s):  
Growth Factor ◽  
Cardiovascular Effects ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Growth Factor I
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