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Submitted on April 12, 2007
Accepted on September 12, 2007
Neuroscience Graduate Program, and Department of Psychiatry, University of Cincinnati Medical Center, Building E, ML 0506, 2170 E. Galbraith Road, Cincinnati, OH 45237
* To whom correspondence should be addressed. E-mail: mary.nguyen{at}uc.edu.
The Visible Burrow System (VBS) is a model used to study chronic social stress in colony housed rats. A hierarchy develops among the males resulting in dominant (DOM) and subordinate (SUB) animals. Hierarchy associated changes in body weight, body composition, behavior, and neuroendocrine measures have been observed. After 14 days of VBS housing, SUB have decreased body weight, elevated corticosterone, and decreased testosterone (T) compared to DOM and controls (CON) placing SUB in an ideal endocrine state to regain lost body weight as adipose tissue. It is hypothesized that maintaining constant androgen concentrations in SUB males during stress will prevent body weight loss by maintaining more lean body mass. To test this, animals were gonadectomized and implanted with Silastic implants containing T, 5
-dihydrotestosterone (DHT), or cholesterol (CHOL). Implants maintained constant physiological levels of T. Standard Intact, T, and DHT implant colonies formed hierarchies, while CHOL colonies did not. Androgen manipulations significantly altered offensive and defensive behaviors only on the first day of VBS housing. After VBS stress, Intact, T, and DHT SUB weighed less and lost more adipose and lean tissue than DOM and CON males, whereas DOM primarily lost adipose tissue. However, upon recovery, DHT SUB maintained more lean tissue than intact SUB. Oral glucose tolerance tests revealed that glucose clears faster in stressed T implanted males that have increased adipose tissue. Overall, these data suggest that constant androgen concentrations in SUB do not prevent weight loss and changes in body composition during stress but does so during recovery.
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| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |