Decreased intravenous glucose tolerance and low plasma insulin response in spiny mice (Acomys cahirinus)

Abstract

A technique was developed to permit estimation of intravenous glucose tolerance and the concomitant immunoreactive insulin (IRI) response in the Geneva colony of the semi-desert rodent Acomys cahirinus. Following intravenous injection of glucose 1.5 g/kg, young Acomys (2-3 months, 25-35g body weight) had a significantly lower glucose tolerance (p<0.01) and a smaller 30 rain integrated plasma IRI response (p < 0.001) than age and weight matched albino mice. With increasing age (8 and 21 months) and body weight (57 to 100 g) of the Acomys, glucose tolerance and plasma IRI response decreased further, and in the 21 month old group there were 2 overtly diabetic animals. There was a significant negative correlation between intravenous glucose toleraa:ce and body weight in older Acomys. The results suggest that pancreatic B-cell responsiveness to glucose is impaired in Acomys of all ages, and that this is associated with poor glucose tolerance which may be aggravated by obesity.

Proinsulin synthesis in islets of Langerhans from spiny mice (Acomys cahirinus). comparison with rats and mice

“…Furthermore, even when this is adhered to, differences noted between species must be interpreted cautiously: what is 'normal' for one species may not be normal for another. With these restrictions in mind, studies have been performed on proinsulin synthesis in islets of Langerhans from Acomys cahirinus, the spiny mouse, in which insulin release is markedly insensitive to glucose, when compared with other rodents such as rats or mice [6][7][8][9].…”

“…Standard rat insulin, kindly prepared by Dr. J. Schlichtkrull (Novo Research Institute, Copenhagen, Denmark) was used for the assay of rat and also of mouse samples; standard human insulin (Dr. Schlichtkrull) was used for the assay of acomys samples as previously described [6]. lesI porcine insulin was prepared by the method of Hunter and Greenwood [15].…”

“…The results demonstrate a decreased responsiveness of proinsulin synthesis to glucose in acomys and are discussed in terms of the known decreased sensitivity of insulin release in this animal. Acomys cahirinus maintained in the Geneva colony exhibit hyperplasia of the islets of Langerhans [1][2][3] and a retarded as well as reduced rate of insulin release in response to glucose challenge by comparison with rats or mice [4][5][6][7]. These differences in the response profile to glucose have been detected in vivo, after either intraperitoneal [4][5] or intravenous [6] glucose injection, and in vitro, using isolated islets [7][8][9].…”

“…Acomys cahirinus maintained in the Geneva colony exhibit hyperplasia of the islets of Langerhans [1][2][3] and a retarded as well as reduced rate of insulin release in response to glucose challenge by comparison with rats or mice [4][5][6][7]. These differences in the response profile to glucose have been detected in vivo, after either intraperitoneal [4][5] or intravenous [6] glucose injection, and in vitro, using isolated islets [7][8][9]. While acomys islets respond slowly to glucose, the total release of insulin over a two hour period may be comparable to that of rats, at least at higher glucose concentrations [7][8][9], suggesting predominantly early decreased sensitivity to glucose.…”

“…These differences in the response profile to glucose have been detected in vivo, after either intraperitoneal [4][5] or intravenous [6] glucose injection, and in vitro, using isolated islets [7][8][9]. While acomys islets respond slowly to glucose, the total release of insulin over a two hour period may be comparable to that of rats, at least at higher glucose concentrations [7][8][9], suggesting predominantly early decreased sensitivity to glucose.…”