Estradiol treatment, physical activity, and muscle function in ovarian-senescent mice
Estradiol (E 2) treatment in young adult, ovariectomized mice increases physical activity and reverses deleterious effects on skeletal muscle. Here we test the hypothesis that E 2 treatment improves muscle function and physical activity in aged, ovarian-senescent mice. Plasma E 2 levels and vaginal...
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| Published in: | Experimental gerontology Vol. 46; no. 8; pp. 685 - 693 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
England
Elsevier Inc
01-08-2011
|
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Estradiol (E
2) treatment in young adult, ovariectomized mice increases physical activity and reverses deleterious effects on skeletal muscle. Here we test the hypothesis that E
2 treatment improves muscle function and physical activity in aged, ovarian-senescent mice. Plasma E
2 levels and vaginal cytology confirmed ovarian senescence in 20-month-old C57BL/6 mice. Mice were then randomly divided into activity groups, having access to a running wheel or not, and further into those receiving E
2 or placebo. Placebo-treated mice wheel ran more than E
2-treated mice (
P
=
0.03), with no difference between treatment groups in cage activities such as time spent being active and ambulation distance (
P
≥
0.55). Soleus muscles from aged mice that wheel ran adapted by getting larger and stronger, irrespective of E
2 status (
P
≤
0.02). Soleus muscle fatigue resistance was greater in mice treated with E
2 (
P
=
0.02), but maximal isometric tetanic force was not affected (
P
≥
0.79). Because E
2 treatment did not improve physical activity or overall muscle function in the aged, ovarian-senescent mice as predicted, a second study was initiated to examine E
2 treatment of young adult mice prematurely ovarian senescent from exposure to the chemical, 4-vinylcyclohexene diepoxide (VCD). Four-month-old C57BL/6 female mice were dosed with oil (control) or VCD. Vaginal cytology confirmed ovarian senescence in all mice treated with VCD 63
days after the onset of dosing, and then a subset of the VCD mice received E
2 (VCD
+
E
2). Wheel running distance did not differ among control, VCD, and VCD
+
E
2 mice (
P
≥
0.34). Soleus muscle concentric, isometric, and eccentric in vitro forces were greater in VCD
+
E
2 than in VCD mice (
P
<
0.04), indicating beneficial estrogenic effects on muscle function. In general, aged and young mice with senescent ovaries were less responsive to E
2 treatment, in terms of physical activities and muscle function, than what has previously been shown for young, ovariectomized mice. These results bring forth the possibility that some component of the residual, follicle-depleted ovarian tissue influences physical activity in mice or that aging diminishes the responsiveness of skeletal muscle and related tissues to E
2 treatment.
► Wheel running provoked positive adaptations to soleus muscles of aged mice. ► E
2 protected soleus muscle fatigue but not force in aged, ovarian-senescent mice. ► Young, ovarian-senescent mice had greater soleus muscle force with E
2 treatment. |
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| Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
| ISSN: | 0531-5565 1873-6815 |
| DOI: | 10.1016/j.exger.2011.04.006 |