Long-term differential modulation of genes encoding orexigenic and anorexigenic peptides by leptin delivered by rAAV vector in ob/ob mice. Relationship with body weight change.
We investigated the long-term effects of physiological levels of leptin produced by gene therapy on body weight (BW) and expression of genes that encode orexigenic and anorexigenic peptides in the hypothalamus. Recombinant adeno-associated viral vector (rAAV), a non-pathogenic and non-immunogenic vector, encoding leptin (betaOb) was generated and administered iv to ob/ob mice lacking endogenous leptin. Whereas the lowest dose of rAAV-betaOb (6x10(9) particles) was ineffective, the middle dose (6x10(10) particles) curbed BW gain without affecting food consumption for 75 days of observation. A ten-fold higher dose (6x10(11) particles) resulted in increased blood leptin levels and suppressed both BW gain and food consumption throughout the duration of the experiment. rAAV-betaOb doses that either curbed BW without affecting food consumption or evoked BW loss and reduced food intake, decreased the expression of genes encoding the orexigenic peptides, neuropeptide Y and agouti-related peptide in the ARC, and the two doses were equally effective. Concomitantly, the expression of genes encoding the anorexigenic peptide, alpha-melanocyte stimulating hormone and cocaine-and-amphetamine regulatory transcript, was augmented with the latter gene displaying a dose-dependant response. These results document the efficacy of delivering biologically active leptin for extended periods by an iv injection of rAAV-betaOb and show that physiological leptin concentrations simultaneously exert a tonic inhibitory effect on orexigenic and a stimulatory effect on anorexigenic signaling in the hypothalamus. This intricate dynamic interplay induced by leptin regulates BW with or without an effect on food intake in leptin-deficient ob/ob mice. Further, these results suggest that gene therapy is an effective mode of delivery to the hypothalamus of those therapeutic proteins that cross the blood-brain barrier to ameliorate neuroendocrine disorders.
Dhillon
H
H
Department of Physiology, University of Florida Brain Institute, College of Medicine, 32610, Gainesville, FL, USA.
Ge
Y
Y
Minter
R M
RM
Prima
V
V
Moldawer
L L
LL
Muzyczka
N
N
Zolotukhin
S
S
Kalra
P S
PS
Kalra
S P
SP
D054369:Agouti-Related Protein; D000818:Animals; D001835:Body Weight; D000229:Dependovirus; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D036341:Intercellular Signaling Peptides and Proteins; D020738:Leptin / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008820:Mice, Obese; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009478:Neuropeptide Y / Q000235:genetics*; D011333:Pro-Opiomelanocortin / Q000235:genetics*; D011506:Proteins / Q000235:genetics*; D013997:Time Factors; D000521:alpha-MSH / Q000235:genetics*; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
D054369:Agouti-Related Protein; D036341:Intercellular Signaling Peptides and Proteins; D020738:Leptin; D009419:Nerve Tissue Proteins; D009478:Neuropeptide Y; D011506:Proteins; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D000521:alpha-MSH; D011333:Pro-Opiomelanocortin