Physiology- Scholarly Publications

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Browsing Physiology- Scholarly Publications by Author "Adekunbi, DA"

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    Open Access
    Coffee consumption attenuates insulin resistance and glucose intolerance in rats fed on high-sucrose diet.
    (2013) Morakinyo, AO; Adekunbi, DA; Dada, KA; Adegoke, OA
    Several epidemiological evidences indicate that consumption of coffee is associated with a lower risk of type 2 diabetes mellitus (T2DM) however; there is dearth of experimental data to support these observations. Given that associations do not necessarily infer causality, the present study was designed to investigate the effect of coffee consumption on glucose regulation, T2DM and the probable mechanisms of action, using an animal model. The effect of coffee (2-fold dilution) by oral gavage on normal and high sucrose-solution (HSS) fed (30 % w/v) rats was evaluated. The results showed that consumption of coffee significantly increase glucose tolerance and insulin sensitivity (p<0.05) along with significant improvement in SOD and GSH activities. In addition, lipid indices such as TG and LDL as well as the lipid peroxidation marker (MDA) were markedly reduced (p<0.05) in rats fed with coffee compared with that of the HSS fed rats. These findings suggest that coffee consumption improves insulin sensitivity, glucose tolerance in HSS-fed rat possibly via inhibition of oxidative stress.
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    Open Access
    Dietary Cocoa (Theobroma cacao) and Turmeric (Curcuma longa) Consumption: A Comparison of Metabolic Effect in High-Fat Fed Rats.
    (2015) Morakinyo, AO; Adekunbi, DA; Ajibola, WR; Adegoke, OA
    A growing number of studies have reported beneficial health effects of cocoa and turmeric, including atherosclerosis, hypertension and insulin resistance. Relatively few studies have investigated the preventive or therapeutic effects of cocoa and turmeric against obesity-related metabolic disorders and co-pathologies. The study was undertaken to determine the effects of cocoa and turmeric powder supplementation on glucose tolerance, insulin sensitivity and lipid profile in rats fed with high-fat diet (HFD). Twenty-four (24) male Sprague-Dawley rats were initially divided into two groups of six and eighteen rats; the group of 18 rats was fed with HFD while the other group of 6 rats consumed the control diet. After seven weeks on the dietary regimen, 12 rats from the HFD group were shifted to either cocoa-supplemented (50 mg/kg diet) or turmeric-supplemented (100 mg/kg diet) with six rats in each group, while the remaining rats continued on the HFD for another 7 weeks. Throughout the study, food intake and body weights were measured and recorded. Thereafter, OGTT and ITT were performed; fat pads were excised and weighed immediately. Blood samples were also collected via the retro-orbital sinus to measure the levels of cholesterol, triglycerides, HDL and LDL. Data obtained from this study showed that dietary cocoa and turmeric supplementation reduces body weight gain, retroperitoneal and testicular fat accretion, improves lipid profile, ameliorates glucose intolerance and enhances insulin sensitivity in the HFD fed- obese rats. Dietary supplementation with cocoa and turmeric ameliorates obesity-related hyperglycemia, glucose intolerance and insulin resistance in HFD fed obese rats. Notably, both nutriceuticals were capable of improving glucose tolerance by increasing insulin sensitivity.
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    Open Access
    Magnesium upregulates insulin receptor and glucose transporter-4 in streptozotocin-nicotinamide-induced type-2 diabetic rats
    (2018) Morakinyo, AO; Samuel, TA; Adekunbi, DA
    Objective. We investigated the eff ects of magnesium supplementation on glucose tolerance, insulin sensitivity, oxidative stress as well as the concentration of insulin receptor and glucose transporter-4 in streptozotocin-nicotinamide induced type-2 diabetic (T2D) rats. Methods. Rats were divided into four groups designated as: 1) control (CTR); 2) diabetic untreated (DU); 3) diabetic treated with 1 mg of Mg/kg diet (Mg1-D); and 4) diabetic treated with 2 mg of Mg/kg diet (Mg2-D). T2D was induced with a single intraperitoneal (i.p.) injection of freshly prepared streptozotocin (55 mg/kg) aft er an initial i.p. injection of nicotinamide (120 mg/kg). Glucose tolerance, insulin sensitivity, lipid profile, malondialdehyde (MAD) and glutathione content, insulin receptors (INSR) and glucose transporter-4 (GLUT4), fasting insulin and glucose levels were measured, and insulin resistance index was calculated using the homeostatic model assessment of insulin resistance (HOMA-IR). Results. Magnesium supplementation improved glucose tolerance and lowered blood glucose levels almost to the normal range. We also recorded a noticeable increase in insulin sensitivity in Mg-D groups when compared with DU rats. Lipid perturbations associated T2D were significantly attenuated by magnesium supplementation. Fasting glucose level was comparable to control values in the Mg-D groups while the HOMA-IR index was signifi cantly lower compared with the DU rats. Magnesium reduced MDA but increased glutathione concentrations compared with DU group. Moreover, INSR and GLUT4 levels were elevated following magnesium supplementation in T2D rats. Conclusion. These findings demonstrate that magnesium may mediate eff ective metabolic control by stimulating the antioxidant defense, and increased levels of INSR and GLUT4 in diabetic rats.
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    Open Access
    Role of amygdala kisspeptin in pubertal timing in female rats
    (2017) Adekunbi, DA; Li, XF; Li, S; Adegoke, OA; Iranloye, BO; Morakinyo, AO; Lightman, SL; Taylor, PD; Poston, L; O'Bryne, KT
    To investigate the mechanism by which maternal obesity disrupts reproductive function in offspring, we examined Kiss1 expression in the hypothalamic arcuate (ARC) and anteroventral periventricular (AVPV) nuclei, and posterodorsal medial amygdala (MePD) of pre-pubertal and young adult offspring. Sprague-Dawley rats were fed either a standard or energydense diet for six weeks prior to mating and throughout pregnancy and lactation. Male and female offspring were weaned onto normal diet on postnatal day (pnd) 21. Brains were collected on pnd 30 or 100 for qRT-PCR to determine Kiss1 mRNA levels. Maternal obesity increased Kiss1 mRNA expression in the MePD of pre-pubertal male and female offspring, whereas Kiss1 expression was not affected in the ARC or AVPV at this age. Maternal obesity reduced Kiss1 expression in all three brain regions of 3 month old female offspring, but only in MePD of males. The role of MePD kisspeptin on puberty, estrous cyclicity and preovulatory LH surges was assessed directly in a separate group of post-weanling and young adult female rats exposed to a normal diet throughout their life course. Bilateral intra-MePD cannulae connected to osmotic mini-pumps for delivery of kisspeptin receptor antagonist (Peptide 234 for 14 days) were chronically implanted on pnd 21 or 100. Antagonism of MePD kisspeptin delayed puberty onset, disrupted estrous cyclicity and reduced the incidence of LH surges. These data show that the MePD plays a key role in pubertal timing and ovulation and that maternal obesity may act via amygdala kisspeptin signaling to influence reproductive function in the offspring.