Abstract
Previous studies showed that short photoperiod increased brown fat (BAT) mass and reduced gonadal size and gonadal hormone secretion in hamsters. The present study investigated the possibility that the effects on BAT were dependent on reduced levels of gonadal hormones. BAT from male Syrian hamsters exposed to short photoperiod for 10 wk was significantly greater in mass, protein content, and total maximal citrate synthase and β-hydroxyacyl-CoA dehydrogenase activities than was BAT from long-photoperiod hamsters. These differences between short- and long-photoperiod exposure were observed in hamsters housed at 21 as well as at 8°C. Short photoperiod also increased the total recovered mitochondrial GDP binding, a finding consistent with increased BAT thermogenic capacity. These short-photoperiod effects were neither mimicked by castration of long-photoperiod hamsters nor prevented by high levels of testosterone administered to short-photoperiod animals. Castration did attenuate the effects of short photoperiod on BAT growth if, after surgery and prior to short-photoperiod exposure, the animals were housed at a long photoperiod for 2-3 wk. In contrast, in hamsters immediately placed at short photoperiod after surgery, castration did not inhibit short-photoperiod effects. The present three experiments demonstrate that, in addition to increasing BAT mass, short photoperiod elevates the thermogenic capacity of BAT, and this elevation does not require the absence or a much reduced testosterone level.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Regulatory Integrative and Comparative Physiology |
| Volume | 251 |
| Issue number | 5 |
| State | Published - 1986 |
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ASJC Scopus subject areas
- Physiology
Cite this
Decreased testosterone levels do not mediate short-photoperiod-induced brown fat changes. / Kott, K. S.; Moore, B. J.; Horwitz, Barbara A.
In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 251, No. 5, 1986.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Decreased testosterone levels do not mediate short-photoperiod-induced brown fat changes
AU - Kott, K. S.
AU - Moore, B. J.
AU - Horwitz, Barbara A
PY - 1986
Y1 - 1986
N2 - Previous studies showed that short photoperiod increased brown fat (BAT) mass and reduced gonadal size and gonadal hormone secretion in hamsters. The present study investigated the possibility that the effects on BAT were dependent on reduced levels of gonadal hormones. BAT from male Syrian hamsters exposed to short photoperiod for 10 wk was significantly greater in mass, protein content, and total maximal citrate synthase and β-hydroxyacyl-CoA dehydrogenase activities than was BAT from long-photoperiod hamsters. These differences between short- and long-photoperiod exposure were observed in hamsters housed at 21 as well as at 8°C. Short photoperiod also increased the total recovered mitochondrial GDP binding, a finding consistent with increased BAT thermogenic capacity. These short-photoperiod effects were neither mimicked by castration of long-photoperiod hamsters nor prevented by high levels of testosterone administered to short-photoperiod animals. Castration did attenuate the effects of short photoperiod on BAT growth if, after surgery and prior to short-photoperiod exposure, the animals were housed at a long photoperiod for 2-3 wk. In contrast, in hamsters immediately placed at short photoperiod after surgery, castration did not inhibit short-photoperiod effects. The present three experiments demonstrate that, in addition to increasing BAT mass, short photoperiod elevates the thermogenic capacity of BAT, and this elevation does not require the absence or a much reduced testosterone level.
AB - Previous studies showed that short photoperiod increased brown fat (BAT) mass and reduced gonadal size and gonadal hormone secretion in hamsters. The present study investigated the possibility that the effects on BAT were dependent on reduced levels of gonadal hormones. BAT from male Syrian hamsters exposed to short photoperiod for 10 wk was significantly greater in mass, protein content, and total maximal citrate synthase and β-hydroxyacyl-CoA dehydrogenase activities than was BAT from long-photoperiod hamsters. These differences between short- and long-photoperiod exposure were observed in hamsters housed at 21 as well as at 8°C. Short photoperiod also increased the total recovered mitochondrial GDP binding, a finding consistent with increased BAT thermogenic capacity. These short-photoperiod effects were neither mimicked by castration of long-photoperiod hamsters nor prevented by high levels of testosterone administered to short-photoperiod animals. Castration did attenuate the effects of short photoperiod on BAT growth if, after surgery and prior to short-photoperiod exposure, the animals were housed at a long photoperiod for 2-3 wk. In contrast, in hamsters immediately placed at short photoperiod after surgery, castration did not inhibit short-photoperiod effects. The present three experiments demonstrate that, in addition to increasing BAT mass, short photoperiod elevates the thermogenic capacity of BAT, and this elevation does not require the absence or a much reduced testosterone level.
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UR - http://www.scopus.com/inward/citedby.url?scp=0023038323&partnerID=8YFLogxK
M3 - Article
C2 - 3777221
AN - SCOPUS:0023038323
VL - 251
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 5
ER -