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Propolis, a resinous material produced by worker bees from the leaf buds and exudates of plants, is reported to possess various therapeutic properties. The aim of this study was to investigate the effects of propolis on biochemical parameters and histopathologic findings in carp Cyprinus carpio L. exposed to arsenic. A sublethal concentration of arsenic (0.01 mg l-1) and/or 10 mg l-1 propolis were administered to fish for 1 wk. Catalase (CAT) activities and malondialdehyde (MDA) levels were determined in liver, gill and muscle tissues in control, arsenic only, propolis only and arsenic+propolis treatment groups. Results showed that CAT activity decreased in the arsenic group compared to the control and propolis groups. CAT activity in the arsenic+propolis group was significantly higher compared to the arsenic group. MDA levels in fish exposed to 0.01 mg l-1 arsenic significantly increased compared to the control group. However, MDA levels in the arsenic+propolis group were significantly lower compared to the arsenic group. Histopathological changes in the liver, gill and muscle tissues of carp were examined by light microscopy: various changes were observed in all tissues of fish in the arsenic group. Propolis showed important antioxidant effects against arsenic toxicity in all fish tissues.

Nitric oxide (NO), produced by endothelial NO synthase, is recognised as a central antiinflammatory and antiatherogenic principle in the vasculature. Epidemiological and clinical studies have demonstrated that a growing list of natural products, as components of the daily diet or phytomedical preparations, may improve vascular function by enhancing NO bioavailability. In this article, we investigated antioxidant effects of propolis on biochemical parameters in kidney and heart tissues of acute NO synthase inhibited rats by Nω-nitro-l-arginine methyl ester (l-NAME). There was increase (p < 0.001) in the activities of catalase and malondialdehyde levels in the l-NAME treatment groups when compared with control rats, but NO levels were decreased in both kidney and heart tissues. There were statistically significant changes (p < 0.001) in these parameters of l-NAME + propolis treated rats as compared with l-NAME-treated group. In summary, propolis may influence endothelial NO production.

This study showed the effects of propolis on biochemical and hematological parameters in chronic nitric oxide synthase inhibited rats by Nω-Nitro-L-arginine methyl ester (L-NAME). Rats are given L-NAME for 15 days and the propolis for the last 5 days with L-NAME together. The levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and gamma glutamyltransferase in the L-NAME group compared to control group have increased (P&lt;0.05). The levels of these parameters in L-NAME+propolis group compared to the L-NAME group have decreased (P&lt;0.05). L-NAME caused increase (P&lt;0.05) in levels of glucose, albumin, globulin, creatinine, urea, triglyceride and cholesterol. Erythrocyte number, total leukocyte, hemoglobin, hematocrit, neutrophil and monocyte decreased (P&lt;0.05), platelets and lymphocyte increased (P&lt;0.05) in L-NAME+propolis group compared to the L-NAME group. The study concluded that homeostasis is modulated in L-NAME administrated rats by adding propolis which causes increasing generation of vascular nitric oxide.

Reduction in the synthesis or bioavailability of nitric oxide plays a significant role in the development of hypertension. Propolis is a resinous product collected by honeybees from various plant sources. Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the biosynthesis of catecholamines. The aim of this study was to examine the effect of propolis on blood pressure (BP), TH, and total RNA levels in the adrenal medulla, heart, and hypothalamus tissues in chronic nitric oxide synthase (NOS)-inhibited rats by N(w)-nitro-l-arginine methyl ester (L-NAME). Rats received NOS inhibitor (L-NAME) for 15 days to produce hypertension and propolis for the last 5 days. TH activity and total RNA levels significantly increased in adrenal medulla, heart, and hypothalamus tissues in L-NAME-treated groups (P < .05). TH activity and total RNA levels of L-NAME+propolis-treated rats reduced (P < .05) compared with L-NAME-treated groups. TH activity in propolis-treated rats was reduced to the control values. L-NAME led to a significant increase in BP compared with the control group. Propolis administration to L-NAME-treated rats reduced BP but this was not statistically significant compared to L-NAME-treated groups. These results suggest that propolis decreases TH activity in NOS-inhibited hypertensive rats and thereby may modulate the synthesis of catecholamine and BP.

Biochemical and hematological parameters in blood of rainbow trout treated to various concentrations of propolis for 96 h were determined. Total leukocyte count and granulocytes values increased (p<0.05) in 0.02 and 0.03 g/L propolis groups. There was a decrease in agranulocytes (p<0.05) erythrocytes, hemoglobin and hematocrit values for fish exposed to 0.02 and 0.03 g/L propolis. MCV and MCH values (p<0.05) were significantly increased; 0.02 and 0.03 g/L propolis caused an increase (p<0.05) in the levels of glucose, blood urea nitrogen, triglyceride, total cholesterol, lactate dehydrogenase, amylase and gamma glutamyltransferase. There was a decrease in the levels of aspartate aminotransferase and alkaline phosphatase. Hematological and biochemical protective effects of 0.01 g/L propolis were investigated. Dose-dependent effects of propolis on blood of fish can be favorable, opening new perspectives of investigation on their biological properties and utilization.