Stimulation by leptin of 3H GDP binding to brown adipose tissue of fasted but not fed rats.
OBJECTIVE
To assess the effects of intracerebroventricular (i.c.v.) leptin administration on rats fed ad libitum or fasted on 3H GDP binding to brown adipose tissue (BAT).


METHODS
Groups of 5-6 ten-week-old male Wistar rats.


METHODS
An i.c.v. cannula was inserted and unilateral denervation of interscapular brown adipose tissue (BAT) was performed 5 d before each study. Thereafter, leptin was infused i.c.v. during 72 h while rats were fed ad libitum or fasted. Vehicle-infused, pair-fed or fasted rats were used as controls.


METHODS
3H GDP binding to innervated and denervated BAT mitochondria.


RESULTS
3H GDP binding to innervated or denervated BAT of rats fed ab libitum compared to vehicle-infused, pair-fed rats was not increased by i.c.v. leptin. 3H GDP binding was lower in fasted than in fed rats, and the difference was larger in innervated than denervated BAT. I.c.v. leptin increased 3H GDP binding by 30% in innervated, and by 51% in denervated BAT (P < 0.05) in fasted rats.


CONCLUSIONS
I.c.v. leptin does not increase 3H GDP binding to BAT of rats fed ad libitum compared to pair-fed (food-restricted) rats. In contrast, i.c.v. leptin produces a mild stimulation of 3H GDP binding to BAT of fasted rats. This effect is not mediated by the sympathetic nervous system, because it is observed in both innervated and denervated BAT. These results are compatible with the concept that, in fasting rats, the decrease in leptin secretion contributes to the reduction in 3H GDP binding to BAT mitochondria.
Institute of Physiology, Faculty of Medicine, University of Lausanne, Switzerland.
J F
JF
Surmely
M J
MJ
Voirol
N
N
Stefanoni
F
F
Assimacopoulos-Jeannet
J P
JP
Giacobino
E
E
Jéquier
R C
RC
Gaillard
L
L
Tappy
D002001:Adipose Tissue, Brown / Q000294:innervation / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects; D003714:Denervation; D005215:Fasting; D005502:Food; D006153:Guanosine Diphosphate / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D020738:Leptin; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D011506:Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014284:Triiodothyronine / Q000097:blood
D007328:Insulin; D020738:Leptin; D011506:Proteins; D014284:Triiodothyronine; D006153:Guanosine Diphosphate