EFFECTS OF ACROMEGALY TREATMENT AND GROWTH-HORMONE ON ADIPOSE-TISSUE LIPOPROTEIN-LIPASE

Lipoprotein lipase (LPL) hydrolyzes lipoprotein triglyceride into none sterified fatty acids, which are then reesterified and stored in adipo se tissue. Previous studies have demonstrated increases in LPL in resp onse to insulin-like growth factor I and GH when added in vitro. This study examined the effects of acromegaly treatment on adipose tissue L PL. Ten patients with clinically active acromegaly were recruited. A f asting adipose tissue biopsy was performed both before and 3 months af ter treatment with octreotide (8 patients) or surgery plus octreotide (2 patients). With treatment, mean baseline insulin-like growth factor I levels fell from 6.41 to 3.98 U/mL (normal, <2.2 U/mL; P < 0.05), a nd serum glycohemoglobin fell from 8.6 to 7.2 (normal, <6.8). Adipose LPL was measured in the heparin-released fraction as well as the cellu lar fraction extracted with nonionic detergent (EXT). After treatment of acromegaly, there was no change in heparin-released fraction LPL ac tivity or immunoreactive mass. However, there was an increase in EXT a ctivity from 0.73 +/- 0.33 to 1.83 +/- 0.58 nEq/min-10(6) cells (mean/-SEM; P < 0.05) and an increase in EXT mass from 4.1 +/- 0.89 to 11.4 +/- 2.0 ng/10(6) cells (P < 0.05). There was no change in LPL messeng er ribonucleic acid levels with treatment, determined using both quant itative polymerase chain reaction and Northern blotting. Thus, treatme nt of acromegaly resulted in an increase in the intracellular level of the LPL protein, with no change in messenger ribonucleic acid levels, suggesting posttranscriptional regulation of LPL. These changes in LP L may be due to improved insulin sensitivity, or to other changes asso ciated with acromegaly treatment.