489 - Hematologic, Plasma Biochemical, and Lipid Analysis of Neonatal Rats Exposed to Phytosterols in Lipid Emulsions

Poster Number: 489
Publication Number: 489.424

Naureen Memon, Goryeb Children's Hospital, Morristown, NJ, United States; Aimee Herdt, MANA, Morristown, NJ, United States; Chris Lee, Biomedical Research Institute of New Jersey, Cedar Knolls, NJ, United States; Elizabeth A. Eckman, BRInj, Cedar Knolls, NJ, United States

Background: Traditional lipid emulsions (LE) are derived from 100% soybean oil (SO) and contain high concentrations of ω6 fatty acids (FA) and plant cholesterols, known as phytosterols (PS). Fish-oil (FO) containing LE contain high concentrations of ω3 FA and lower concentrations of PS. Animal and human studies have repeatedly shown that FO containing LE are hepatoprotective; whether this protection is due to the altered FA profile, a decrease in PS concentration, or a combination thereof is currently unknown. Using a novel phytosterolemia rat model, we studied the isolated effects of PS exposure that mimics PS exposure with short-term parenteral nutrition use in newborns.

Objective: To characterize hepatic/lipid panels and blood cell counts in neonatal rats exposed to PS.

Design/Methods: β-sitosterol, campesterol, and stigmasterol were dissolved in 2-hydroxypropyl-β-cyclodextrin (vehicle) to create a PS solution. Sprague-Dawley rat pups received daily intraperitoneal injections of PS solution from P0-P13 at doses approximating PS content in 2 g/kg/d (n=7) or 4 g/kg/d (n=5) Intralipid. Vehicle exposed pups (n=12) served as controls. Plasma complete blood count (CBC), hepatic function tests, and lipid levels were analyzed in representative subsets of rats by IDEXX BioAnalytics to screen for changes induced by PS exposure. Total bile acid (BA) analysis was repeated using a fluorimetric BA assay (Sigma Aldrich). Results were compared by unpaired t-test or Mann Whitney U test; differences between groups were considered significant if p< 0.05.

Results: Blood analysis from subsets of rats, performed by IDEXX BioAnalytics, showed no significant differences in hepatic function tests (AST, ALT, GGT, total bilirubin, direct bilirubin), lipid levels (cholesterol, LDL, HDL), and CBC (total WBC, differential WBCs, hemoglobin, and platelets); but detected a 40% increase in plasma BA in pups receiving PS solution vs. vehicle (13.37 ± 1.1 vs. 9.33 ± 0.35 µM (mean ± SD), p=0.0037) (Fig 1A). Repeat BA analysis showed a similar, but not statistically significant, 32% increase in BA levels in a larger group of PS exposed pups (n=11) compared to vehicle (n=9) that was not dose-dependent (Fig 1B). Conclusion(s): This is the first study characterizing the independent effects of PS exposure on hepatic and hematologic markers in plasma of a neonatal animal model. Our results suggest that short-term exposure of PS does not result in direct hyperbilirubinemia (an indirect marker of cholestasis) or other changes in hepatic function tests. The increase in BA concentrations in PS exposed pups is intriguing and warrants further investigation.

Bile Acid Concentrations in Neonatal Rats Exposed to PhytosterolsPlasma bile acid concentrations in neonatal rats after 2-week exposure to vehicle (control) or phytosterol (PS) solution as analyzed by (A) IDEXX BioAnalytics and (B) Sigma Aldrich's fluorimetric bile acid assay.