Abstract
Decreased ventromedial hypothalamic (VMH) serotonergic activity occurs in genetic and diet-induced animal models of obesity. We previously found that this activity was lower in adult and in 12-day-old Zucker fa/fa vs. Fa/Fa pups, the fa/fa animals being identified by their greater adiposity. In the present study, we evaluated fa/fa rats (Brown Norway-Zucker hybrids) at ages 2, 4, 7, and 12 days to test the hypothesis that lower VMH serotonergic activity occurs before increased adiposity and/or attenuated energy expenditure. Our results negate this hypothesis. VMH serotonergic activity showed no consistent genotype differences even at 12 days of age. In contrast, by day 7, fa/fa vs. Fa/Fa pups had higher serum leptin concentrations, greater percent body fat, lower resting and cold-induced energy expenditure, and lower activity of brown fat thyroxine 5'-deiodinase, an enzyme that converts thyroxine to triiodothyronine. We conclude that the onset of increased adiposity induced by the fa gene does not require decreased VMH serotonergic activity and that the lower serotonergic activity seen in older fa/fa pups may be secondary to metabolic consequences of the disruption of the leptin regulatory pathway.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology |
| Volume | 274 |
| Issue number | 6 PART 1 |
| State | Published - 1998 |
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Keywords
- Brown adipose tissue
- Brown norway-zucker rats
- Energy expenditure
- Genetic obesity
- Thyroxine 5'-deiodinase
- Uncoupling protein
- Ventromedial hypothalamus
ASJC Scopus subject areas
- Physiology (medical)
Cite this
Adiposity and serum leptin increase in fatty (fa/fa) BNZ neonates without decreased VMH serotonergic activity. / Horwitz, Barbara A; Hamilton, Jock S.; Routh, Vanessa H.; Green, Kerri; Havel, Peter J; Chan, Albert.
In: American Journal of Physiology, Vol. 274, No. 6 PART 1, 1998.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Adiposity and serum leptin increase in fatty (fa/fa) BNZ neonates without decreased VMH serotonergic activity
AU - Horwitz, Barbara A
AU - Hamilton, Jock S.
AU - Routh, Vanessa H.
AU - Green, Kerri
AU - Havel, Peter J
AU - Chan, Albert
PY - 1998
Y1 - 1998
N2 - Decreased ventromedial hypothalamic (VMH) serotonergic activity occurs in genetic and diet-induced animal models of obesity. We previously found that this activity was lower in adult and in 12-day-old Zucker fa/fa vs. Fa/Fa pups, the fa/fa animals being identified by their greater adiposity. In the present study, we evaluated fa/fa rats (Brown Norway-Zucker hybrids) at ages 2, 4, 7, and 12 days to test the hypothesis that lower VMH serotonergic activity occurs before increased adiposity and/or attenuated energy expenditure. Our results negate this hypothesis. VMH serotonergic activity showed no consistent genotype differences even at 12 days of age. In contrast, by day 7, fa/fa vs. Fa/Fa pups had higher serum leptin concentrations, greater percent body fat, lower resting and cold-induced energy expenditure, and lower activity of brown fat thyroxine 5'-deiodinase, an enzyme that converts thyroxine to triiodothyronine. We conclude that the onset of increased adiposity induced by the fa gene does not require decreased VMH serotonergic activity and that the lower serotonergic activity seen in older fa/fa pups may be secondary to metabolic consequences of the disruption of the leptin regulatory pathway.
AB - Decreased ventromedial hypothalamic (VMH) serotonergic activity occurs in genetic and diet-induced animal models of obesity. We previously found that this activity was lower in adult and in 12-day-old Zucker fa/fa vs. Fa/Fa pups, the fa/fa animals being identified by their greater adiposity. In the present study, we evaluated fa/fa rats (Brown Norway-Zucker hybrids) at ages 2, 4, 7, and 12 days to test the hypothesis that lower VMH serotonergic activity occurs before increased adiposity and/or attenuated energy expenditure. Our results negate this hypothesis. VMH serotonergic activity showed no consistent genotype differences even at 12 days of age. In contrast, by day 7, fa/fa vs. Fa/Fa pups had higher serum leptin concentrations, greater percent body fat, lower resting and cold-induced energy expenditure, and lower activity of brown fat thyroxine 5'-deiodinase, an enzyme that converts thyroxine to triiodothyronine. We conclude that the onset of increased adiposity induced by the fa gene does not require decreased VMH serotonergic activity and that the lower serotonergic activity seen in older fa/fa pups may be secondary to metabolic consequences of the disruption of the leptin regulatory pathway.
KW - Brown adipose tissue
KW - Brown norway-zucker rats
KW - Energy expenditure
KW - Genetic obesity
KW - Thyroxine 5'-deiodinase
KW - Uncoupling protein
KW - Ventromedial hypothalamus
UR - http://www.scopus.com/inward/record.url?scp=33746769714&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33746769714&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:33746769714
VL - 274
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 6 PART 1
ER -