Indomethacin decreases both luteinizing hormone binding and fluidity of testicular microsomal membranes in rat

Effect of anti-inflammatory drugs on splenocyte membrane fluidity

In this study, fluorescence anisotropy measurements were performed using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene to investigate the effects on membrane fluidity resulting from the interaction between nonsteroidal anti-inflammatory drugs (NSAIDs)-indomethacin, diclofenac, piroxicam, tenoxicam, indoprofen, clonixin, and etodolac-and mouse splenocyte membranes. This study was performed in splenocyte membranes because most of the fluidity studies have been performed in membrane models; thus, clear correlations of the pharmacological action of drugs with molecular effects at the cellular membrane level were lacking. Besides providing a basis for studying the molecular mechanism of pharmacological action of NSAIDs, this research provides a data analysis of steady-state anisotropy measurements, taking into account that the probe itself strongly influences the data given that this problem is usually overlooked. Results show that the anti-inflammatory drugs indomethacin, diclofenac, piroxicam, and tenoxicam increase the membrane fluidity in a concentration-dependent manner. Their order of effectiveness reflected in their respective IC50 values (concentration of each NSAID required to increase the fluidizing effect ratio by 50%) is as follows: tenoxicam>piroxicam>indomethacin>clonixin. For the other drugs, the perturbation in membrane fluidity is not evident under these circumstances.

Interaction of Clonixin with EPC Liposomes Used as Membrane Models

In this work, an overall analysis of clonixin interaction with liposomes was achieved using different techniques, which allowed the evaluation of the change in different membrane's characteristics as well as the possible location of the drug in the membrane. Clonixin acidity constants were obtained and the values are 5.5 +/- 0.08 and 2.2 +/- 0.04. Clonixin partition coefficient (K(p)) between liposomes and water was also determined using derivative spectrophotometry, fluorescence quenching, and zeta-potential (zeta-potential). These three techniques yielded similar results. zeta-potential measurements were performed and an increase of the membrane negative charge with an increase of drug concentration was observed. Drug location within the bilayer was performed by fluorescence quenching using a set of n-(9-anthroyloxy) fatty acid probes (n = 2, 6, 9, and 12). The fluorescence intensity of all probes was quenched by the drug. This effect is more noticeable for the outer located probe, indicating that the drug is positioning in the external part of the membrane. These same probes were used for steady-state anisotropy measurements to determine the perturbation in membrane structure induced by clonixin. Clonixin increased membrane fluidity in a concentration dependent manner, with the highest perturbation occurring nearby the 2-AS probe, closely located to the bilayer surface.

Modulation of receptor-mediated gonadotropin action in rat testes by dietary fat

The effect of feeding diets enriched with 18:2 omega 6, 18:3 omega 3, or saturated fatty acids on lipid composition and receptor-mediated action of luteinizing hormone/human chorionic gonadotropin (LH/hCG) in rat testicular plasma membranes was investigated. Linoleic and alpha-linolenic acid treatments reduced total phospholipid and cholesterol content of the testicular plasma membrane and altered membrane phospholipid composition. Change in phospholipid and cholesterol content after feeding the polyunsaturated fats decreased cholesterol to phospholipid ratios and binding capacity of the LH/hCG receptor in the testicular plasma membrane. LH-stimulated adenylate cyclase activity was decreased in animals fed the linolenic acid-rich diet. NaF-stimulated adenylate cyclase activity was decreased in animals fed diets high in either polyunsaturated fatty acid. Decreased plasma membrane LH/hCG receptor content was associated with decreased testosterone production in Leydig cells in response to LH in the linolenic acid-fed group. It is suggested that change in cholesterol-to-phospholipid ratios alters the physical properties of testicular plasma membranes in a manner that influences accessibility of LH/hCG receptors in testicular tissue.

Hypercholesterolemic effect of indomethacin in the rat

The effect of indomethacin on serum lipid constituents of the albino rat was investigated. Indomethacin 1 mg/kg, but not 10 mg/kg body weight, orally administered daily for 3 days, significantly raised total serum cholesterol level from a control value of 58.17 +/- 3.40 to 108.50 +/- 15.3 (N = 10; P less than 0.05) and free cholesterol level from 52.96 +/- 2.21 to 101.17 +/- 9.52 (N = 10; P less than 0.05). Indomethacin, 1 mg/kg p.o. daily for 3 days, also raised serum triglycerides from 45.0 +/- 7.33 to 118.30 +/- 9.05 (N = 10; P less than 0.001), while it reduced phospholipid content from 189.57 +/- 58.04 to 98.75 +/- 25.85 (N = 10; P less than 0.05). The higher dose of indomethacin 10 mg/kg p.o. daily for three days resulted in a significant increase in non-esterified fatty acids, triglycerides and total calcium, while it reduced total bilirubin, phosphorous and total lipid content of rat serum. The results indicate that according to the dose administered, indomethacin could lead to serious derangements in lipid profiles.