Relationships among serum triacylglycerol, fat pad weight, and lipolysis in iron-deficient rats

We studied the relationships among serum triacylglycerol (TG), fat pad weig ht, and lipolytic response to norepinephrine (NE) in iron-deficient rats. W e used male Sprague-Dawley International Golden Standard rats. The rats wer e randomly divided into four groups: two iron-adequate groups for 1 week (1 A) and 5 weeks (5A), and two iron-deficient groups for 1 week (1D) and 5 we eks (5D), based on the AIN-93G diet. Iron-deficient treatment caused a sign ificant decrease in hemoglobin (Hb) and hematocrit (Hct) values and an incr ease in relative heart weight in 1D and 5D rats. Although serum TG was not affected by the 1-week iron-deficient treatment, it was significantly incre ased by 5-week iron-deficient treatment. The 1-week iron-deficient treatmen t significantly decreased the relative weight of the retroperitoneal fat pa ds, but not that of the epididymal fat pads. On the other hand, the 5-week iron-deficient treatment significantly decreased the relative weight of bot h fat pads; the degree of decrease was 41% and 32% for retroperitoneal and epididymal fat pads, respectively. Basal lipolysis significantly decreased in the epididymal adipocytes from 1D rats, whereas lipolytic response to NE markedly increased. No effect due to the 5-week treatment on basal lipolys is was observed in either retroperitoneal or epididymal adipocytes. In addi tion, lipolytic response to NE significantly increased in the retroperitone al, but not the epididymal adipocytes. These results demonstrate that the e ffects of an iron-deficient diet on fat pad weight are different, depending on the duration of the treatment and the location of fat pads. In addition , iron deficiency-caused hypertriacylglycerolima may be predominantly relat ed to the increase in lipolysis in retroperitoneal rather than in epididyma l adipocytes. The data further show that the increase in lipolysis of epidi dymal adipocytes occurs in the earlier stage prior to a severe iron-deficie nt state. (J. Nutr. Biochem. 11:455-460, 2000) (C) Elsevier Science Inc. 20 00. All rights reserved.