Counter-regulatory responses to Telfairia occidentalis-induced hypoglycaemia

Abstract

Background: Telfairia occidentalis (TO) has many biological activities including blood glucose regulation. Thus, it is being used in the treatment of diabetes mellitus. TO has been shown to cause insulin-mediated hypoglycaemia, which leads to post-hypoglycaemic hyperglycaemia. However, the mechanism involved in the post-hypoglycaemic hyperglycaemia is still poorly understood.

Objective: This research was designed to determine the response of glucoregulatory hormones and enzymes to TO treatment.

Methods: Thirty-five male Wistar rats were divided into seven oral treatment groups (n = 5/group), which received either of 100 mg/kg or 200 mg/kg TO for 7-, 10- or 14 days.

Results: The 7-day treatment with TO significantly increased the levels of insulin, glucagon, and glucose-6-phosphatase (G6Pase) activity but decreased the levels of glucose, adrenaline, and glucokinase (GCK) activity. The 10-day treatment with 100 mg/kg TO increased glucose and decreased GCK activity while 200 mg/kg for the same duration increased glucose, insulin, GCK and G6Pase activities but reduced glucagon. The 14-day treatment with 100 mg/kg TO decreased glucose and glucagon but increased cortisol, while 200 mg/kg TO for same duration increased insulin, but reduced glucagon and GCK activity.

Conclusion: The TO's post-hypoglycaemic hyperglycaemia results from increased glucagon and G6Pase activity, and reduced GCK activity. Moreover, the glucagon response mainly depends on glucose rather than insulin.

Keywords: ANOVA, Analysis of Variance; Avidin-HRP, Avidin-Horseradish Peroxidase; Counter-regulatory hormones; EGP, Endogenous glucose production; ELISA, Enzyme-linked immunosorbent assay; G6P, Glucose-6-phosphate; G6PD, Glucose-6-phosphate dehydrogenase; G6Pase, Glucose-6-phosphatase; GCK, Glucokinase; Glucoregulatory enzymes; Insulin; LDH, Lactate dehydrogenase; LSD, Least Significance Difference; NAD, Nicotinamide adenine dinucleotide; NIH, National Institutes of Health; Plasma glucose; SEM, Standard error of mean; SPSS, Statistical Package for the Social Sciences; TO, Telfairia occidentalis; Telfairia occidentalis; cAMP, Cyclic adenosine monophosphate.

Fig. 1

Effects of Telfairia occidentalis on plasma glucose levels in rats. ∗p < 0.05 vs. control; ^#p < 0.05 vs. animals treated with 100 mg/kg Telfairia occidentalis (TO) for same duration.

Fig. 2

Effects of Telfairia occidentalis on plasma insulin levels in rats. ∗p < 0.05 vs. control; ^#p < 0.05 vs. animals treated with 100 mg/kg Telfairia occidentalis (TO) for same duration.

Fig. 3

Effects of Telfairia occidentalis on plasma glucagon levels in rats. ∗p < 0.05 vs. control; ^#p < 0.05 vs. animals treated with 100 mg/kg Telfairia occidentalis (TO) for same duration.

Fig. 4

Effects of Telfairia occidentalis on plasma adrenaline levels in rats. ∗p < 0.05 vs. control; ^#p < 0.05 vs. animals treated with 100 mg/kg Telfairia occidentalis (TO) for same duration.

Fig. 5

Effects of Telfairia occidentalis on plasma cortisol levels in rats. ∗p < 0.05 vs. control; ^#p < 0.05 vs. animals treated with 100 mg/kg Telfairia occidentalis (TO) for same duration.

Fig. 6

Effects of Telfairia occidentalis on liver glucokinase activity in rats. ∗p < 0.05 vs. control; ^#p < 0.05 vs. animals treated with 100 mg/kg Telfairia occidentalis (TO) for same duration.

Fig. 7

Effects of Telfairia occidentalis on liver glucose-6-phosphatase activity in rats. ∗p < 0.05 vs. control; ^#p < 0.05 vs. animals treated with 100 mg/kg Telfairia occidentalis (TO) for same duration.