{"id":2406,"date":"2015-04-25T06:55:19","date_gmt":"2015-04-25T06:55:19","guid":{"rendered":"http:\/\/biomedpharmajournal.org\/?p=2406"},"modified":"2016-12-03T05:49:50","modified_gmt":"2016-12-03T05:49:50","slug":"comparative-changes-in-biomakers-of-oxidative-stress-in-ocular-humour-of-honey-and-fructose-fed-wistar-rats","status":"publish","type":"post","link":"https:\/\/biomedpharmajournal.org\/staging\/vol5no1\/comparative-changes-in-biomakers-of-oxidative-stress-in-ocular-humour-of-honey-and-fructose-fed-wistar-rats\/","title":{"rendered":"Comparative Changes in Biomakers of Oxidative Stress in Ocular Humour of Honey and Fructose Fed Wistar Rats"},"content":{"rendered":"

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

Fructose (C6<\/sub>H12<\/sub>O6<\/sub>) is a 6 carbon ketose.\u00a0 It is the sweetest simple sugar mainly consumed as sweetener in foods. Food sources of fructose include confectioneries, sucrose and honey.<\/p>\n

Honey is a mixture of sugars and other compounds.\u00a0 Honey contains mainly fructose (about 38.5%) and glucose (about 31.0%), and minute amounts of maltose, sucrose, and other complex carbohydrates1<\/sup>. It also contains tiny amounts of several compounds thought to function as antioxidants, including chrysin, pinobanksin, vitamin C, catalase, and pinocembrin2<\/sup> with trace levels of vitamins and minerals.<\/p>\n

Fructose feeding has been reported to induce insulin resistance and increase blood glucose3<\/sup>.\u00a0 These metabolic derangements were observed to increase intraocular pressure (IOP) and augment the level of oxidative stress in the organ3<\/sup>.<\/p>\n

The severity of diabetic retinopathy has been observed to be related to length and magnitude of exposure to hyperglycaemia4<\/sup>. \u00a0Patients with evidence of retinopathy have about\u00a0 15% decrease in \u00a0aqueous flow and this could impact \u00a0intraocular pressure (IOP), though mechanism is yet to be clarified.<\/p>\n

Although honey contains high amounts\u00a0 of fructose, its consumption lowers\u00a0 blood glucose, lipids, C-reactive proteins and homocysteine when compared with\u00a0 dextrose or sucrose feeding3.<\/sup>\u00a0 Therefore, honey may not significantly\u00a0 affect IOP and ocular glucose, but scientific evidence is yet to be sufficient.\u00a0 In this study,\u00a0 the levels of oxidative stress biomarkers (Glucose, reduced glutathione [GSH]\u00a0 and malondialdehyde, [MDA]) in ocular humour of fructose and honey fed Wistar rats were determined in order to compare the\u00a0 impact of honey and fructose feeding on ocular glucose and associated stress.<\/p>\n

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

Animal Care and Handling<\/em><\/strong><\/p>\n

Forty-nine male and female rats weighing 74-102 g were used in the study. The rats \u00a0were divided into seven (7) groups. Group C, the control rats were given rat chow.\u00a0 Groups H1<\/sub>, H2<\/sub> and H3<\/sub> were fed with 20%, 30% and 40% honey, respectively.\u00a0 The other experimental groups F1<\/sub>, F2<\/sub> and F3<\/sub> received fructose quantities equivalent to amounts in 20%, 30% and 40% honey.\u00a0 The rats were fed for 28 days and given water ad libidum<\/em>.\u00a0 Cages were cleaned regularly and animals were kept in 12 h light \/ 12 h dark cycle at room temperature (280<\/sup>C-310<\/sup>C).\u00a0 Animal care and handling complied with standard recommendations5<\/sup>.<\/p>\n

Collection of Humour from the Rats<\/em><\/strong><\/p>\n

The two whole eyes of\u00a0 chloroform anaesthetized rat 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<\/strong><\/p>\n

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

The amounts of glucose6<\/sup>, glutathione7<\/sup> and malondialdehyde8<\/sup> in the eye humour were determined using standard procedures as previously described.<\/p>\n

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

Values were expressed as Mean\u00b1SEM and significant differences between means were evaluated by analysis of variance (ANOVA). Post test analysis was carried out using the Turkey multiple comparison test and values of p<\/em><0.05 were considered as statistically significant9<\/sup>.<\/p>\n

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

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

Table 1: Changes in the biomarkers of oxidative stress in the ocular\u00a0humour of honey and fructose fed rats<\/strong><\/p>\n\n\n\n\n\n\n\n\n\n\n\n
Group<\/strong><\/td>\nBiomarkers of oxidative stress in ocular humour<\/strong><\/td>\n<\/tr>\n
Glucose(mmol\/L)<\/strong><\/td>\nGSH(mg\/g tissue)<\/strong><\/td>\nMDA (X10 -5<\/sup>mmol\/mL)<\/strong><\/td>\n<\/tr>\n
C<\/td>\n2.16\u00b10.06<\/td>\n48.2\u00b14.3<\/td>\n0.47\u00b10.07<\/td>\n<\/tr>\n
H1<\/sub><\/td>\n2.30\u00b10.07<\/td>\n46.7\u00b14.2<\/td>\n0.53\u00b10.07<\/td>\n<\/tr>\n
H2<\/sub><\/td>\n2.36\u00b10.11<\/td>\n45.9\u00b15.2<\/td>\n0.57\u00b10.03<\/td>\n<\/tr>\n
H3<\/sub><\/td>\n2.44\u00b10.12<\/td>\n47.9\u00b16.6<\/td>\n0.61\u00b10.07<\/td>\n<\/tr>\n
F1<\/sub><\/td>\n2.39\u00b10.20<\/td>\n44.9\u00b14.8<\/td>\n0.58\u00b10.07<\/td>\n<\/tr>\n
F2<\/sub><\/td>\n2.56\u00b10.23*<\/td>\n40.1\u00b14.1<\/td>\n0.69\u00b10.07<\/td>\n<\/tr>\n
F3<\/sub><\/td>\n2.65\u00b10.32*<\/td>\n35.6\u00b15.6**<\/td>\n0.76\u00b10.05**<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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

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

MDA = Malondialdehyde.<\/p>\n

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

H1<\/sub> =80% grower\u2019s mash+20% honey.<\/p>\n

H2<\/sub>=70% grower\u2019s mash +30% honey.<\/p>\n

H3<\/sub> =60% grower\u2019s mash +40% honey.<\/p>\n

F1<\/sub>=84.4% grower\u2019s mash+7.2g (Glucose) and 8.4g (Fructose).<\/p>\n

F2<\/sub>=76.6% grower\u2019s mash +10.8g (Glucose) and 12.6g (Fructose).<\/p>\n

F3<\/sub> =68.8% grower\u2019s mash +14.4g (Glucose) and 16.8g (Fructose).<\/p>\n

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

* Significantly different (p<0.05) from control value<\/p>\n

** Significantly different (p<0.05) from both control and honey fed groups. <\/em><\/p>\n

\u00a0<\/em><\/p>\n

The administration of honey (p<\/em>>0.05)\u00a0 or fructose (p<\/em><0.05) increased\u00a0 the concentration of glucose in ocular humour in a dose-dependent manner when compared with control. There was a significant (p<\/em><0.05) indication of\u00a0 oxidative stress, as judged by the levels of GSH and MDA induced by the highest amount (40%) of fructose.\u00a0 The level of stress induced by honey was minimal and insignificant (p<\/em>>0.05).\u00a0 Honey reduced GSH levels (p<\/em>>0.05)\u00a0\u00a0 and the associated lipid peroxidation as indicated by the MDA amounts (Table I) compare well with control value.<\/p>\n

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

Recall that in this study, the concentrations of glucose, GSH and MDA in ocular humour\u00a0 were measured in rats fed with either fructose or honey. \u00a0Overall, fructose feeding when compared with control and honey fed groups significantly (p<<\/em>0.05)\u00a0\u00a0 increased the amounts of glucose,\u00a0 levels of oxidative stress and lipid peroxidation in ocular humour of exposed Wistar rats.\u00a0 But values obtained with honey feeding compare well with control values.<\/p>\n

Concentrations of oxidative stress biomarkers (GSH and MDA) in the ocular humour of fructose fed rats\u00a0 indicate significant cellular and molecular levels of oxidative stress.<\/p>\n

This stress which can increase IOP has been shown by the over expression of intracellular nitric oxide synthase, iNOS, an enzyme primarily involved in mitochondrial lipid peroxidation and damage of cell membrane10<\/sup>.\u00a0 Such over expression has been validated by the accumulation of intracellular\u00a0 MDA. Fructose feeding also increased ocular glucose and this observation agrees with previous reports3<\/sup>.\u00a0 It has been reported that fructose feeding affects IOP via increased blood glucose.\u00a0 Compromise in GLUT 5 (fructose transporter) and receptors has been shown11<\/sup> to elicit metabolic disturbances associated with increase in blood glucose and lipids.\u00a0 Honey consumption has been observed to lower plasma glucose, C-reactive proteins, homocysteine and blood lipids in healthy, diabetic and hyperlipidaemic subjects3<\/sup>. Honey, unlike fructose appears not to seriously induce ocular stress and this may not affect IOP significantly.\u00a0 Nevertheless, further studies are required to fully document the\u00a0 ocular benefits arising from honey consumption.<\/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 hyperlipidaemic subjects: comparison with dextrose and sucrose. J Med Food<\/em>. 7(1):100-7.<\/li>\n
  2. Beck-Nielsen, H., Pedersen, O. and Lindskov, H. (1980). Impaired cellular insulin binding and insulin sensitivity induced by high fructose feeding in normal subjects. Am. J. Clin. Nutr. 33: 273-278<\/li>\n
  3. Buege, J.A. and Aust, S.D. (1978). Microsomal lipid peroxidation. Method Enzymol. 52: 302 \u2013 305.<\/li>\n
  4. Crane, E. (1999). The world history of bee and honey hunting. Gerald Duckworth and Co., London.<\/li>\n
  5. Ensminger, A.H., Ensminger, M.E., Kondale, J.E. and Robson, J.R.K. (1983). Food and Nutrition Encyclopedia. Pegus Press, California.<\/li>\n
  6. Gheldof, N., Wang, X.H and Engesth, N.J. (2002). Identification and quantification of antioxidant components of honeys from various floral sources. Agric. Food Chem<\/em>. 50: 5870-5877.<\/li>\n
  7. Halliwell, B. and Gutteridge, J. (1984). Lipid peroxidation oxygen radicals, cell damage, antioxidant therapy. Lancet<\/em> 23: 1396- 1398.<\/li>\n
  8. Howell, D.C. (2002). Statistical methods for psychology. 5th<\/sup> (ed.), Pacific Grove, Duxbury.<\/li>\n
  9. Kikkawa, S., Kadohara, M. and Kawasaki, H. (1992). Glutathione concentration in oral cancer tissues. Commun. Chem. Pathol. Pharmacol<\/em>. 78: 289- 309.<\/li>\n
  10. National Research Council, NRC (1985). Guide for the care and use of laboratory animals. Publication No. 85-23 (Rev.), National Institute of Health, NIH, Bethesda, MD.<\/li>\n
  11. Trinder, P. (1969). Determination of blood glucose using 4-amino-phenazone as oxygen acceptor. Clin. Pathol<\/em>. 22 (2): 246-248.<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

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