Effects of opium on cholesterol metabolism in rats fed normal and high-fat/high-cholesterol diet

Abstract

There is a misconception that opium can lower blood sugar and cholesterol levels. Hence, this study aimed to investigate the influences of opium on the expression of key cholesterol metabolism genes in the liver and intestine of rats receiving a cholesterol-rich diet. Male Wistar rats were randomly divided into four groups (n = 6): normal control, opium addiction, hypercholesterolemic diet, and opium addiction received hypercholesterolemic diet. After 28 days, the blood glucose levels, liver enzymes, and cholesterol in the rat's serum were measured. The cholesterol regulatory genes and transporters such as 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, low-density lipoprotein receptor (LDL-R), cholesterol 7 alpha-hydroxylase 1 (CYP7A1) (in liver tissue), and ATP Binding cassette subfamily g member 5 and 8 (ABCG5 and ABCG8), and Niemann-Pick C1-like 1 protein (NPC1L1) (in intestinal tissue) were measured. Intestinal morphological changes were also evaluated. Opium decreased serum glucose and total cholesterol levels (P < 0.05). In contrast, the levels of liver enzymes increased compared to the normal control group (P < 0.05). Histological examinations revealed that opium caused disorganization, deformation, and destruction of cells in intestinal tissue. Real-time PCR analysis demonstrated that opium increased the expression of LDL receptor genes, HMG-CoA reductase enzyme, and CYP7A1 in the liver compared to the normal control group (P < 0.05). The changes of ABCG8 and NPC1L1 transporters in intestinal tissue were not significant. Opium had beneficial effects on blood lipid and glucose levels, but histological findings indicated destructive effects on intestinal tissues.

Keywords: Cholesterol; Lipid; Opium; Rat.

Fig. 1

Changes in the weight of rats and their liver weight in the studied groups. The results are reported as Mean ± SEM. ns: non-significance compared to the normal control group and comparison between groups. NC: normal control, HC: high cholesterol, OP: opium-addicted, and OP + HC: opium-addicted + high cholesterol, gr: gram.

Fig. 2

Serum levels of fasting blood sugar and liver enzymes in the studied groups. The results are shown as Mean ± SEM. ns: no significance compared to the control group. *: p < 0.05, **: p < 0.01, ***: p < 0.001, and ****: p < 0.0001 compared to the normal control group. #: p < 0.05, ##: p < 0.01, and ###: p < 0.001 compared to specific group. NC: normal control, HC: high cholesterol, OP: opium-addicted, and OP + HC: opium-addicted + high cholesterol, FBS: fasting blood sugar, AST: aspartate aminotransferase, ALT: alanine aminotransferase.

Fig. 3

The results of examining LDL-R, HMG-CoA-R, and CYP7A1 gene expression in the liver of the studied groups. The results are reported as Mean ± SEM. ns: no significance compared to the control group, *: p < 0.05, **: p < 0.01, ****: p < 0.0001 compared to the normal control group, #: p < 0.05, ##: p < 0.01 compared to specific group. NC: normal control, HC: high cholesterol, OP: opium-addicted, and OP + HC: opium-addicted + high cholesterol, LDL-R: low-density lipoprotein receptor, HMG-CoA R: 3-hydroxy-3-methylglutaryl coenzyme A reductase, CYP7A1: cholesterol 7 alpha-hydroxylase 1.

Fig. 4

The results of examining NPC1L1, ABCG5, and ABCG8 gene expression in the intestines of the studied groups. The results are reported as Mean ± SEM. ns: no significance compared to the control group, *: p < 0.05 compared to the normal control group, #: p < 0.05, ##: p < 0.01 compared to compared to specific group. NC: normal control, HC: high cholesterol, OP: opium-addicted, and OP + HC: opium-addicted + high cholesterol, ABCG5: ATP binding cassette subfamily g member 5, ABCG8: ATP Binding cassette subfamily g member 8, NPC1L1: Niemann-Pick C1-like 1 protein.

Fig. 5

Hematoxylin-eosin (H&E) staining of different treated groups (A) and the severity of the intestinal injury (B) in different groups. A: Histological changes in the intestine in control groups (A), group receiving hypercholesterol diet (B), group receiving opium (C), group receiving opium and hypercholesterol diet (D)(10x magnification, scale bar: 20 µm). Blue arrow: villi, red arrow: Crypts of Lieberkuhn, and black arrow: villi length. B: The severity of the intestinal injury. ****: p < 0.0001 compared to the normal control group, #: p < 0.05, ##: p < 0.01 compared to compared to specific group. NC: normal control, HC: high cholesterol, OP: opium-addicted, and OP + HC: opium-addicted + high cholesterol.