{"id":1713,"date":"2015-03-28T08:30:15","date_gmt":"2015-03-28T08:30:15","guid":{"rendered":"http:\/\/biomedpharmajournal.org\/?p=1713"},"modified":"2017-01-04T06:57:34","modified_gmt":"2017-01-04T06:57:34","slug":"changes-in-biomakers-of-ocular-pressure-and-oxidative-stress-in-aqueous-humour-of-honey-fed-rats","status":"publish","type":"post","link":"https:\/\/biomedpharmajournal.org\/staging\/vol4no1\/changes-in-biomakers-of-ocular-pressure-and-oxidative-stress-in-aqueous-humour-of-honey-fed-rats\/","title":{"rendered":"Changes in Biomakers of Ocular Pressure and Oxidative Stress in Aqueous Humour of Honey Fed Rats"},"content":{"rendered":"

Introduction<\/strong><\/p>\n

Honey is a mixture of sugars and other compounds. With respect to carbohydrates, honey is mainly fructose (about 38.5%) and glucose (about 31.0%) (Crane, 1999), making it similar to the synthetically produced inverted sugar syrup which is approximately 48% fructose, 47% glucose, and 5% sucrose. Honey’s remaining carbohydrates include maltose, sucrose, and other complex carbohydrates (Crane, 1975). As with all nutritive sweeteners, honey is mostly sugars and contains only trace amounts of vitamins or minerals. Honey also contains tiny amounts of several compounds thought to function as antioxidants, including chrysin, pinobanksin, vitamin C, catalase, and pinocembrin (Gheldof, et al., <\/em>2002). The specific composition of any batch of honey depends on the flowers available to the bees that produced the honey.<\/p>\n

It has been previously reported that aqueous flow in the retina was decreased by 15% in patients with type 1 diabetes without evidence of microvascular complications, and severity of diabetic retinopathy has been observed to be related to length and magnitude of exposure to hyperglycaemia (Ensminger, et al<\/em>., 1983). Diabetic retinopathy appears to exist concurrently with microvascular abnormalities in the kidney, and signals diabetic nephropathy (Cook, et al<\/em>., 2005). If a decrease in aqueous flow accompanies diabetic retinopathy, and if these changes are related by common pathophysiologic mechanisms, it is hypothesized that patients with evidence of retinopathy will have decreased aqueous flow that could impact \u00a0intraocular pressure (IOP). The relationship between rate of aqueous flow and the severity of complications in the eyes of patients with diabetes is not known.<\/p>\n

Although fructose does not appear to acutely increase insulin levels, chronic exposure seems to indirectly cause hyperinsulinemia and obesity through other mechanisms. One proposed mechanism involves GLUT5, a fructose transporter that is found to have significantly higher expression levels in young Zucker obese rats compared with lean controls. As the rats age and become diabetic, GLUT5 abundance and activity is compromised, causing an even more marked insulin resistance over lean rats, implying a possible role of GLUT5 receptors in the pathology of metabolic syndrome associated with fructose feeding and insulin resistance (Hadjduch, 2004). In rats fed 66% fructose for 4weeks, insulin receptor mRNA, and subsequent insulin receptor numbers in skeletal muscle and liver were significantly lower compared with rats fed a standard chow diet. Compromise in insulin receptor and\u00a0 signaling may elicit metabolic effects associated with increase in blood glucose and lipids.\u00a0 Fructose feeding affects IOP, but honey consumption lowers plasma glucose, C-reactive protein, homocysteine and blood\u00a0 lipids in healthy, diabetic and hyperlipidemic subjects (Al-Waili, 2004).\u00a0 However, the effect of honey on biomarkers of ocular pressure (glucose, albumin) and oxidative stress (GSH, MDA) are not clearly documented.\u00a0\u00a0 This study attempts to provide useful evidence regarding the effect of natural honey on ocular pressure and oxidative status.<\/p>\n

Materials and Method<\/strong><\/p>\n

Animal care and handling<\/strong><\/p>\n

Forty-nine male and female rats weighing 78-95g were used in the study. The rats \u00a0were divided into seven (7) groups. Group A, the control rats were given rat chow.\u00a0 Groups B, C and D were fed with 20%, 30% and 40% honey, respectively.\u00a0 The other experimental groups E, F and G received fructose quantities equivalent to amounts in 20%, 30% and 40% honey.\u00a0 The rats were fed for 28 days and allowed free access to water.\u00a0 Cages were cleaned regularly and animals were kept in 12 h light and 12 h dark cycle.\u00a0 Animal care and handling complied with standard recommendations.<\/p>\n

Collection of humour from the rats<\/strong><\/p>\n

The two whole eyes of\u00a0 chloroform anaesthetized rats were plucked and punctured in order to collect the humour.\u00a0 The humour obtained was centrifuged at 1000rpm for 15min at 370<\/sup>C.\u00a0 The supernatant was carefully removed with Pasteur pipette and stored frozen until needed for analysis. \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/strong><\/p>\n

Analysis<\/strong><\/p>\n

The amounts of glucose (Trinder, 1969), albumin (Braford, 1976), glutathione (Kikkawa, et al<\/em>., 1992) and malondialdehyde (Buege and Aust, 1978) in the eye humour were determined using standard procedures previously adopted by other workers.<\/p>\n

Statistical analysis<\/strong><\/p>\n

The group Mean \u00b1SEM was calculated for each biomarker and significant differences between means were evaluated by analysis of variance (ANOVA). Post test analysis was carried out using the Turkey multiple comparison test. Values of P<\/em>< 0.05 were considered as statistically significant.<\/p>\n

Results<\/strong><\/p>\n

The results obtained from this investigation into the changes in biomarkers of ocular pressure and oxidative stress in honey fed rats are presented in Table 1.<\/p>\n

Table 1: Changes in the biomarkers of ocular pressure and oxidative\u00a0stress in the aqueous humour of honey fed rats<\/strong><\/p>\n\n\n\n\n\n\n\n\n\n
Markers<\/strong><\/td>\nA<\/strong><\/td>\nB<\/strong><\/td>\nC<\/strong><\/td>\nD<\/strong><\/td>\nE<\/strong><\/td>\nF<\/strong><\/td>\nG<\/strong><\/td>\n<\/tr>\n
Ocular pressure<\/strong><\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/tr>\n
\u00b7\u00a0\u00a0\u00a0 Glucose(mmol\/L)<\/strong><\/td>\n2.44\u00b10.08<\/td>\n2.50\u00b10.09<\/td>\n2.52\u00b10.14<\/td>\n2.54\u00b10.14<\/td>\n2.49\u00b10.22<\/td>\n2.52\u00b10.25<\/td>\n2.55\u00b10.31<\/td>\n<\/tr>\n
\u00b7\u00a0\u00a0\u00a0 Albumin(g\/dL)<\/strong><\/td>\n3.04\u00b10.09<\/td>\n2.97\u00b10.08<\/td>\n3.08\u00b10.61<\/td>\n3.14\u00b10.72<\/td>\n2.88\u00b10.50<\/td>\n2.90\u00b10.80<\/td>\n2.99\u00b10.06<\/td>\n<\/tr>\n
 <\/p>\n

Oxidative Stress<\/strong><\/td>\n

<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/tr>\n
\u00b7\u00a0\u00a0\u00a0 GSH(mg\/g)<\/strong><\/td>\n44.6\u00b14.1<\/td>\n44.7\u00b14.0<\/td>\n46.9\u00b15.6<\/td>\n47.9\u00b17.3<\/td>\n46.9\u00b14.6<\/td>\n40.1\u00b13.9<\/td>\n34.6\u00b15.5<\/td>\n<\/tr>\n
\u00b7\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/sup>MDA<\/strong><\/p>\n

(X10 -5<\/sup>nmmol\/mL)<\/strong><\/td>\n

0.40\u00b10.07<\/td>\n0.43\u00b10.07<\/td>\n0.45\u00b10.03<\/td>\n0.46\u00b10.07<\/td>\n0.44\u00b10.07<\/td>\n0.49\u00b10.07<\/td>\n0.56\u00b10.06<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Values are expressed as Mean \u00b1SD for n=7 rats\/group.<\/em><\/p>\n

GSH =Glutathione (reduced).<\/em><\/p>\n

MDA = Malondiadehyde.<\/em><\/p>\n

A =100% grower\u2019s mash (Control).<\/em><\/p>\n

B =80% grower\u2019s mash+20% honey.<\/em><\/p>\n

C=70% grower\u2019s mash +30% honey.<\/em><\/p>\n

D =60% grower\u2019s mash +40% honey.<\/em><\/p>\n

E =84.4% grower\u2019s mash+7.2g (Glucose) and 8.4g (Fructose).<\/em><\/p>\n

F=76.6% grower\u2019s mash +10.8g (Glucose) and 12.6g (Fructose).<\/em><\/p>\n

G =68.8% grower\u2019s mash +14.4g (Glucose) and 16.8g (Fructose).<\/em><\/p>\n

The quantities of glucose\/fructose for Group E, F,and G were equivalent to amounts in 20%,30%,40% honey, respectively<\/em>.<\/p>\n

Increase in albumin and glucose concentrations in the aqueous humours could contribute to the changes in ocular pressure. The administration of honey or fructose, increased the concentration of glucose in the humour in a dose-dependent manner when compared with control. There was also an indication of oxidative stress, as judged by the levels of GSH and MDA induced by increased amount of fructose.\u00a0 The level of stress induced by honey was minimal.\u00a0 It increased GSH with little associated lipid peroxidation<\/p>\n

Discussion<\/strong><\/p>\n

In the present study, the concentrations of glucose, albumin, GSH and MDA in aqueous humour\u00a0 were measured in rats fed with honey. We observed a significant higher concentration of glutathione (GSH) in aqueous humor of rats fed with honey compared with control. These groups of experimental rats have enhanced defense against oxidative stress when compared with the fructose fed groups.<\/p>\n

One of the greatest challenges in oxidation research today is the determination of oxidation stress in vivo<\/em>, because proteins are ubiquitous in all cells and tissues, and are susceptible to oxidation modification. \u00a0\u00a0Concentrations of the oxidative biomarkers (GSH and MDA) in the aqueous humour activates diverse\u00a0 cellular and molecular signals of stress, such as the upregulation of the ocular pressure which,\u00a0 increases IOP and results in oxidative stress.\u00a0 This stress is shown by the over expression of\u00a0 iNOS, and enzyme primarily involved in mitochondrial lipid peroxidation and damage of cell membrane (Halliwell and Gutterridge,\u00a0 1984), validated by the accumulation of intracellular\u00a0 MDA. Honey, unlike fructose appears not to seriously affect ocular stress, but the induced increase in humour\u2019s\u00a0 glucose may disturb ocular pressure.\u00a0 Further studies are required to fully document the\u00a0 implication of the observed increase in ocular glucose.<\/p>\n

Reference<\/strong>s<\/strong><\/p>\n

    \n
  1. Al-Waili N.S. (2004). Natural honey lowers plasma glucose, C-reactive protein, homocysteine, and blood lipids in healthy, diabetic, and hyperlipidemic subjects: comparison with dextrose and sucrose. J Med Food<\/em>.\u00a0 7(1):100-7.<\/li>\n
  2. Bradford,\u00a0 M. (1976).\u00a0 A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem.<\/li>\n
  3. Buege, J.A. and Aust, S.D. (1978). Microsomal lipid peroxidation.\u00a0 Method Enzymol. 52: 302 \u2013 305.<\/li>\n
  4. Cook, M.N., Girman, C.J., Stein, P.P., Alexander, C.M. and Holman, R.R. (2005). Glycemic control continues to deteriorate after sulfonylureas are added to metformin among patients with type 2 diabetes. Diabetes Care 28: 995 \u2013 1000.<\/li>\n
  5. Crane, E. (1999). The world history of bee and honey hunting. Gerald Duckworth and Co., London.<\/li>\n
  6. Ensminger, A.H., Ensminger, M.E., Kondale, J.E. and Robson, J.R.K. (1983). Food and Nutrition Encyclopedia. Pegus Press, California.<\/li>\n
  7. Gheldof, N., Wang, X.H and Engesth, N.J. (2002). Identification and quantification of antioxidant components of honeys from various floral sources. J. Agric. Food Chem<\/em>. 50: 5870-5877.<\/li>\n
  8. Halliwell, B. and Gutteridge, J. (1984). Lipid peroxidation oxygen radicals, cell damage, antioxidant therapy. Lancet<\/em> 23: 1396- 1398.<\/li>\n
  9. Kikkawa, S., Kadohara, M. and Kawasaki, H. (1992). Glutathione concentration in oral cancer tissues.\u00a0 Res. Commun. Chem. Pathol. Pharmacol<\/em>. 78: 289- 309.<\/li>\n
  10. Trinder, P. (1969). Determination of blood glucose using 4-amino-phenazone as oxygen acceptor. J. Clin. Pathol<\/em>. 22 (2): 246-248.<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

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