The Effect of Long-Term Taurine Supplementation and Fructose Feeding on Glucose and Lipid Homeostasis in Wistar Rats - Advances in Experimental Medicine and Biology - page 37

Abbreviations

Fru Fructose

HDL High-density lipoprotein cholesterol

HOMA-IR Homeostasis model assessment of insulin resistance

LDL Low-density lipoprotein cholesterol

OGTT Oral glucose tolerance test

Tau Taurine

5.1 Introduction

Fructose has recently been hypothesized to be one of the main effectors driving
the increased incidence of the metabolic syndrome in countries that have adopted
the Western diet (Lustig et al. 2012 ; Stanhope 2012 ) .
Taurine (2-aminoethanesulfonic acid) is a nonprotein semi-essential amino acid
found in large amounts in both tissues (5-50 mM) and plasma (50-100 mM) and known
to have a number of physiological functions, such as conjugation with bile acids, intra-
cellular osmolyte for volume regulation, and antioxidant properties (Hansen 2001 ) .
In 1935 it was demonstrated by Ackermann et al. that taurine had a beneficial
effect upon glucose homeostasis in diabetic patients (Ackermann and Heinsen
1935 ). Taurine stimulates glycolysis and glycogenesis, thus presenting insulin-like
activity (Dokshina et al. 1976 ). Furthermore, it is evident that plasma and tissue
taurine levels change in a variety of metabolic pathophysiological conditions
(Hansen 2001 ) and taurine concentration in plasma has been demonstrated to
decrease in type 2 diabetic patients (De Luca et al. 2001 ). This reduction in plasma
taurine levels has also been seen in diabetic animal models (Franconi et al. 1995,
1996 ). An increase in taurine intake has been shown to decrease plasma glucose in
type 1 diabetic patients (Elizarova and Nedosugova 1996 ) . However, in studies
examining prediabetic and diabetic complications, differences in fasting plasma
glucose and insulin after taurine supplementation were not reported (Franconi et al.
1996 ; Nishimura et al. 2002 ). Together these data indicate that taurine may have a
protective role in hyperglycemia, something which is corroborated by recent litera-
ture reviews showing an interaction between taurine and diabetes (Franconi et al.
2006 ; Kim et al. 2007 ) .
Several animal studies have shown that taurine prevents fructose-induced insulin
resistance, as judged by both oral glucose tolerance tests and a normalization of
total insulin-induced kinase activity. Furthermore, a high-fructose diet in rats has
been reported to decrease plasma and liver taurine levels (El Mesallamy et al. 2010 ;
Nandhini et al. 2004, 2005 ; Nandhini and Anuradha 2002 ). In a rat model of non-
insulin-dependent diabetes, the Otsuka Long Evans Tokushima Fatty (OLETF) rat
(Kawano et al. 1992 ) taurine supplementation caused a decrease in serum triglycer-
ides and cholesterol, with no effect on body weight and abdominal fat mass (Harada
et al. 2004 ; Nakaya et al. 2000 ) .