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Effects of Caffeine and Caffeine‐containing Kolanut (Cola nitida seed) on Glucose Tolerance of the Rat
Author(s) -
Alada Akinola,
Afolabi Oladele
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.1044.7
Subject(s) - glycogen , chemistry , caffeine , medicine , endocrinology , liver function , glycogen synthase , insulin , glycogen phosphorylase , fructosamine , biochemistry
This study examined the effects of caffeine and kolanut on the glucose tolerance of the rat. Male Wistar albino rats (250 ‐300g) and divided into four groups with 8 rats per group were orally administered ethanolic extract of kolanut (EEK) (6mg/kg), decaffeinated extract of kolanut (DEK) (6mg/kg), caffeine (CAF) (6mg/kg) and distilled water (control) respectively for eight weeks. At 8 weeks, oral glucose tolerance test was carried out on the rats. Plasma glucose concentrations were plotted as a function of time and the areas under the glucose curve (AUGs) calculated. Blood samples and liver biopsies were taken to determine serum insulin levels, liver glycogen, Liver glycogen synthase and phosphorylase activities. Blood glucose was determined by glucose oxidase method. Glycogen level was determined by anthrone method. Radioimmunoassay kit (Diagnostic product) was used to determine serum insulin level. Values are means ± S.E.M, compared by ANOVA and Student t‐test. AUGs increased by 35% and 28% for rats treated with CAF and EEK respectively compared with the control. AUG for for rats treated with DEK was 31% lower than the control. Peak serum insulin levels also increased from 15.1± 0.22µg/ml to 20.65± 0.31 and 20.48± 0.42µg/ml for CAF and EEK respectively and decreased to10.89± 0.01µg/ml for DEK. There was no significant change in the liver glycogen and glycogen synthase activity in all the groups except in CAF group which are 40% and 25% respectively higher than the control. There was no significant difference in the liver phosporylase activity in all the groups. The results showed that caffeine and kolanut extract reduced glucose tolerance most possibly by reducing insulin sensitivity.