Background: In rodents, neurotensin contributes to high fat diet induced obesity by facilitation of intestinal fat absorption. The effect of oral lipid load on plasma proneurotensin and relationship with plasma triglycerides in humans is unknown.
Aim: To investigate the acute effects of an oral lipid load (including both cream and olive oil) on proneurotensin and plasma triglycerides and their interrelationships in healthy individuals.
Setting/ Methods: Twenty-two healthy subjects were given 150 ml of full milk cream (54g fat) and 59 ml of pure olive oil (54 g fat) in the fasted state at two different occasions separated by at least 1 week in random order. Venous blood samples were drawn at fasting,and hourly up to 4 hours after fat ingestion. We compared post-ingestion values of proneurotensin and plasma triglycerides with fasting levels. Further, post ingestion Area Under the Curve (AUC) of proneurotensin was correlated with the AUC of plasma triglycerides.
Results: Rise of plasma proneurotensin and plasma triglycerides were observed after ingestion of cream with maximum increase at 2 hours for proneurotensin [mean (95% confidence interval)] of 22 (12-31) pmol/L (P<0.001) and at 3 hours for triglycerides of 0.60 (0.43-0.78) mmol/L (P<0.001). Similarly, plasma proneurotensin and plasma triglycerides increased after ingestion of olive oil with maximum increase of proneurotensin at 3 hours of 62 (46-78) pmol/L (P<0.001) and plasma triglycerides at 3 hours of 0.32 (0.18-0.45) mmol/L (P<0.001). The post lipid load AUC for proneurotensin correlated significantly with the AUC for plasma triglycerides both after cream (r=0.49, P=0.021) and olive oil (r=0.55, P=0.008), respectively.
Conclusion: Proneurotensin increases after an oral lipid load of both cream and olive oil and the degree of rise of post-ingestion proneurotensin is significantly related to the rise of post-ingestion plasma triglycerides. Our human data support recent results from animal studies suggesting that neurotensin contributes to intestinal absorption of lipids into the blood stream.