EFFECT OF TRIMETHYLAMINE-CARBOMETHOXYBORANE ON GROWTH TRAITS AND LIPID-METABOLISM IN LINES OF MICE SELECTED FOR HIGH AND LOW-FAT CONTENT

The purpose of this study was to determine the effects of the amine ca rboxyborane, trimethylamine-carbomethoxyborane (B), on growth, body co mposition and lipid metabolism in lines of mice differing in fat conte nt as a result of directional selection: high fat content (KF); low fa t content (LF); and random control (RC). Mice were injected ip daily w ith either 20 mg/kg of B dissolved in 1% (w/v) carbomethoxycellulose a s the vehicle or just vehicle (C) from 26 to 42 days of age. Growth ra te, feed intake, feed efficiency, epididymal fat pad weight/BW and per centage body water were not affected by B treatment, but liver weight/ BW was increased (P < 0.001). HF mice had larger epididymal fat pad we ight/BW and less percentage body water when compared to LF mice (P < 0 .001). Treatment with B lowered (P < 0.01) serum triglyceride and chol esterol levels, and selection for divergence in fat content led to pos itive divergence (P < 0.01, (HF - LF) > 0) in serum triglyceride and s erum cholesterol levels; divergence x treatment interactions (P < 0.01 ) were due to administration of B eliminating the line differences pre sent when C was administered. Treatment with B elevated (P < 0.001) HD L cholesterol level and lowered (P < 0.001) chylomicron, LDL and VLDL cholesterol levels, while positive divergence was found for all four f ractions. Fecal triglyceride and cholesterol levels were increased (P < 0.01) by administering B, but were not affected by selection. Hepati c enzyme activity of cholesterol-7 alpha-hydroxylase was elevated (P < 0.001) by treatment with B while activities of other hepatic enzymes were depressed, e.g., acyl-CoA cholesterol acyltransferase. Line diffe rences in activity of several hepatic enzymes also were found. These r esults indicate that B acts as a hypolipidemic agent in both high-fat and low-fat mouse genotypes, lowering serum cholesterol and triglyceri de levels. However, at the administered dose, B had no affect on growt h rate, feed intake, feed efficiency or body fat content.