Abstract
Cyproheptadine administration has been demonstrated to stimulate appetite. Our previous report demonstrated a depression of blood glucose by cyproheptadine irrespective of circulating insulin level in rats.
The aim of the present study is to determine the effect of cyproheptadine on blood glucose, serum insulin and serum growth hormone level during, 1) the standard oral glucose tolerance test (OGTT), and during 2) the intravenous glucose tolerance test (IVGTT).
The subjects were seven apparently healthy males without family history of diabetes, aged from 23 to 25. Blood samples were drawn from the cubital vein before, and 30, 60, 90, and 120 minutes after oral administration of 50g of glucose.
In IVGTT, blood samples were collected before and at 3, 5, 7, 10 minutes and after every ten minute interval until 60 minutes.
Time was counted zero at the start of the intravenous injection of 10 g of glucose in 50% aqueous solution.
After examining all seven subjects with OGTT and IVGTT to obtain control values, cyproheptadine 8mg per day in tablet form, was administered for seven to ten days until the other OGTT and IVGTT were completed. Results obtained are as follows.
Blood glucose levels in subjects under cyproheptadine treatment during OGTT were lower than those of controls. Differences of glucose levels were significant in 60 minutes and 90 minutes during OGTT.
Changes in insulin levels, however, in OGTT after administration of cyproheptadine were minimum. 5 subjects on cyproheptadine had serum growth hormone levels lower than the controls in OGTT, but the differences were not significant.
In IVGTT cyproheptadine had no effect on serum insulin levels.
However, glucose disappearance ratio (K-value) in IVGTT was 1.7±0.1 for the control and 2.6±0.4 for cases with cyproheptadine treatment (p<0.05). These results in combination with our previous report may indicate enhancement of blood glucose utilisation in peripheral tissues irrespective of change in circulating insulin levels in man.
The next suggestion from the present study is that cyproheptadine has no effect on the insulin secretory response of the B cell of the islet of Langerhans during IVGTT in which the effect of the gut factor is neglected and insulinogenesis is a result of a direct hyperglycemic stimulus on the B cell.
