The role of the sex steroids in regulation of physical activity levels in mice

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Bowen, R. (2010). The role of the sex steroids in regulation of physical activity levels in mice. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

Low physical activity (PA) levels are associated with many chronic diseases and place a massive burden on the health care system. The extrinsic environment has been suggested to regulate activity levels, but an increasing prevalence of physical inactivity in developed societies suggests the presence of other regulating factors. The sex steroids affect PA levels, but the regulating mechanisms are not known. The purpose of this study was to evaluate the interrelationship of sex steroids and PA in mice and the involvement of dopamine 1 receptors (Drd1) in sex steroid regulation of PA. First, sex steroid levels were manipulated in male and female mice by gonadectomy and replacement via silastic implants. Wheel running decreased in both sexes after removal of the gonads. Testosterone administration to gonadectomized mice completely reversed the PA deficit while administration of 17β-estradiol recovered 50% of the deficit. Next, the aromatase complex was pharmacologically inhibited. Wheel running levels remained unchanged in normal, orchidectomized, and steroid replaced male mice suggesting the presence of an androgen responsive PA regulating mechanism. Finally, PA levels were observed after orchidectomy in mice receiving either testosterone or a Drd1 antagonist. PA levels were elevated by testosterone, but were unaffected by the antagonist. The levels of Drd1 mRNA in the nucleus acumbens and striatum were evaluated after administration of these two compounds. Drd1 mRNA expression was not different between treatments or compared to control mice. These results suggest that PA is regulated by the estrogens and androgens, but the influence is not regulated by Drd1.

Details
Author

Bowen, Robert

Title

The role of the sex steroids in regulation of physical activity levels in mice

Physical Description

1 online resource (136 pages) : PDF

Date

2010

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

Low physical activity (PA) levels are associated with many chronic diseases and place a massive burden on the health care system. The extrinsic environment has been suggested to regulate activity levels, but an increasing prevalence of physical inactivity in developed societies suggests the presence of other regulating factors. The sex steroids affect PA levels, but the regulating mechanisms are not known. The purpose of this study was to evaluate the interrelationship of sex steroids and PA in mice and the involvement of dopamine 1 receptors (Drd1) in sex steroid regulation of PA. First, sex steroid levels were manipulated in male and female mice by gonadectomy and replacement via silastic implants. Wheel running decreased in both sexes after removal of the gonads. Testosterone administration to gonadectomized mice completely reversed the PA deficit while administration of 17β-estradiol recovered 50% of the deficit. Next, the aromatase complex was pharmacologically inhibited. Wheel running levels remained unchanged in normal, orchidectomized, and steroid replaced male mice suggesting the presence of an androgen responsive PA regulating mechanism. Finally, PA levels were observed after orchidectomy in mice receiving either testosterone or a Drd1 antagonist. PA levels were elevated by testosterone, but were unaffected by the antagonist. The levels of Drd1 mRNA in the nucleus acumbens and striatum were evaluated after administration of these two compounds. Drd1 mRNA expression was not different between treatments or compared to control mice. These results suggest that PA is regulated by the estrogens and androgens, but the influence is not regulated by Drd1.

Genre

doctoral dissertations

Subjects--Topics

Kinesiology
Physiology

Degree

Ph.D.

Keywords

Biological Regulation
Estrogen
Exercise
Locomotion
Sex Hormones
Testosterone

Subject Area

Biology

Advisor(s)

Lightfoot, J Timothy

Committee Members

Tsivitse, Susan
Huet, Yvette
Marriott, Ian
Cann, Arnie

Degree Note

Thesis (Ph.D.)--University of North Carolina at Charlotte, 2010.

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Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

Bowen_uncc_0694D_10088

Permalink

http://hdl.handle.net/20.500.13093/etd:123