Effects of intraperitoneal and intracerebroventricular injection of cinnamaldehyde and yohimbine on blood glucose and serum insulin concentrations in ketamine-xylazine induced acute hyperglycemia

This study was designed to investigate the effects of peripheral [intraperitoneal (IP)] and central [intracerebroventricular (ICV)] administration of cinnamaldehyde on concentrations of blood glucose and serum insulin in the acute hyperglycemia induced by ketamine/xylazine. Yohimbine (a α۲-adrenoceptor antagonist) was used alone and in combination with cinnamaldehyde to explore the α۲-adrenergic receptor contribution. A total of ۴۸ rats were divided into eight groups with six rats in each for IP administration of normal saline, vehicle, cinnamaldehyde (۲۵.۰۰, ۵۰.۰۰ and ۱۰۰ mg kg-۱), yohimbine (۰.۵۰ and ۲.۰۰ mg kg-۱) and cinnamaldehyde plus yohimbine. These rats were used again for ICV administration ۱۵ days after the completion of IP experiment. During this ۱۵ days period, the lateral ventricle of the brain was surgically cannulated for ICV administration of normal saline, vehicle, cinna-maldehyde (۲۵.۰۰, ۵۰.۰۰ and ۱۰۰ µg per rat), yohimbine (۵.۰۰ and ۲۰.۰۰ µg per rat) and cinnamaldehyde plus yohimbine. Blood glucose levels were measured from tail blood using a glucometer and serum insulin concentrations were determined via enzyme-linked immune-sorbent assay kit. The increased levels of blood glucose and the decreased concentrations of serum insulin were significantly decreased and increased, respectively, by separate and combined IP and ICV administrations of cinnamaldehyde and yohimbine. The systemic effects of these chemical compounds were significantly greater than the central ones. Based on the results, it can be argued that cinnamaldehyde has a potential to induce anti-hyperglycemic and antihypoinsulinemic effects. Peripheral and central α۲-adrenegic receptors might be involved in these effects of cinnamaldehyde.

Keywords:

Cinnamaldehyde , Insulin , Ketamine-xylazine hyperglycemia , Yohimbine , Rats