Ef. Rosato et al., INSULIN STIMULATES LIPOPROTEIN-LIPASE ACTIVITY AND SYNTHESIS IN ADIPOCYTES FROM SEPTIC RATS, The Journal of surgical research, 73(1), 1997, pp. 73-79
Gram-negative sepsis suppresses lipoprotein lipase (LPL) activity in a
dipose tissue which contributes, in part, to the altered clearance of
triglycerides. The suppression in LPL activity occurs when plasma insu
lin concentrations are elevated and insulin-stimulated glucose utiliza
tion is impaired. This study was planned to evaluate whether the prese
nce of insulin resistance was responsible for the decrease in adipose
LPL activity. Adipocytes were isolated from epididymal fat pads 24 h a
fter inducing sepsis in male Lewis rats by intravenous injection of 4
x 10(8) colonies of live Escherichia coli/100 g body wt. The decrease
in heparin-releasable (HR) LPL activity in adipocytes from the septic
rats was evident at the time of isolation and maintained in a 20-h cul
ture. After overnight incubation with insulin (10(-8) M), HR LPL activ
ity was stimulated to a greater extent in adipocytes from septic rats
(298%) than in adipocytes from control rats (88%). The insulin stimula
tion of LPL activity during sepsis could not be attributed to insulin-
like growth factor-I (IGF-I) as adipocytes from septic rats appeared t
o be IGF-I resistant. Insulin-treatment (10(-8) M) increased LPL synth
esis 99% in adipocytes from control rats and 136% in adipocytes from s
eptic rats. Insulin treatment also led to a 65 and 62% increase in LPL
mass in adipocytes from control and septic rats, respectively. These
findings indicate that the sepsis-induced decrease in adipose LPL is n
ot due to insulin resistance with respect to LPL. The insulin stimulat
ion of LPL activity in adipocytes from septic rats appears to be media
ted by an increase in LPL synthesis. (C) 1997 Academic Press.