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Chapter 23: Lipids: Bioactive Lipids and Lipid-Sensing Receptors

The omega-3 class of polyunsaturated fatty acids (PUFAs) exerts potent effects on neural development, cardiovascular function, and inflammation. The most active omega-3 PUFAs are DHA and EPA. These PUFA are precursors for which of the following class of biologically active lipids?

A. gangliosides

B. leukotrienes

C. prostaglandins

D. resolvins

E. thromboxanes

Answer D: The resolvins (Rv) have anti-inflammatory actions that lead to the resolution of the inflammatory processes, hence the derivation of their names as resolvins (resolution phase interaction products). The resolvins are synthesized either from eicosapentaenoic acid (EPA) or from docosahexaenoic (DHA). The D-series resolvins are derived from DHA and the E-series from EPA.

You are testing the activity of a fatty acid analog for efficacy in the treatment of the hyperglycemia associated with Type 2 diabetes. You find that inclusion of the compound in the diet of these test subjects results in an increased release of the gut hormone GLP-1. Which of the following fatty acid–binding receptors is most likely activated by your compound in the gut of the test subjects accounting for the observed response?

A. GPR35

B. GPR40

C. GPR41

D. GPR55

E. GPR120

Answer E: GPR120 is specifically activated by long-chain nonesterified fatty acids (NEFAs), in particular in the intestines by α-linolenic acid (ALA), an omega-3 polyunsaturated fatty acid (PUFA). Activation of GPR120 in the intestines results in increased GLP-1 secretion from enteroendocrine L cells.

You are testing a novel lipid molecule for its activity on vascular function in experimental animals. Your results demonstrate that the compound induces vasodilation by causing relaxation of smooth muscle. It also enhances platelet aggregation. These results indicate that your compound is most likely mimicking the effects of which of the following lipids?

A. docosahexaenoic acid, DHA

B. eicosapentaenoic acid, EPA

C. lysophosphatidic acid, LPA

D. lysophosphatidylinositol, LPI

E. oleoylethaolamide, OEA

Answer C: LPA, although being simple in structure, exerts a wide variety of cellular responses in many different cell types. LPA is known to enhance platelet aggregation, smooth muscle contraction, cell proliferation and migration, neurite retraction, and the secretion of chemokines and cytokines. The effects of ...

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