The role of adrenergic receptors in nicotine-induced hyperglycemia in the common African toad (Bufo regularis)

  • GO Isehunwa
  • GO Adewunmi
  • ARA Alada
  • OT Olaniyan

Abstract

The role of adrenergic receptors in nicotine-induced hyperglycaemia has not been well studied in amphibians. Thus, this study investigates the effects of alpha and beta adrenergic receptor blockers in nicotine-induced hyperglycaemia in the common African toad Bufo regularis. Toads fasted for 24 h were anaesthetized with sodium pentobarbitone (3 mg/100 g body weight) intraperitoneally (i.p) and given intravenous (i.v) injection of 0.7% amphibian saline, or nicotine (50 µg/kg), nicotine(50 µg/kg i.v) 30 min after pretreatment with prazosin (0.2 mg/kg i.v), propranolol (0.5 mg/kg i.v) or combination of both prazosin (0.2 mg/kg i.v) and propranolol (0.5 mg/kg, i.v). Thereafter, blood samples were also collected from truncus arteriosus for estimation of blood glucose level using the modified glucose oxidase method. Nicotine caused significant increase (P<0.01) in the levels of blood glucose in the common African toad. Pre-treatment of the toads with prazosin (0.2 mg/kg i.v) or propranolol (0.5 mg/kg, i.v) significantly (p < 0.01) reduced the hyperglycaemia induced by nicotine (50 µg/kg i.v). However, the combination of prazosin (0.2 mg/kg i.v) and propranolol (0.5 mg/kg, i.v) abolished the hyperglycaemic effect of nicotine (50 µg/kg i.v). The above results on glucose metabolism suggests involvement of both alpha and beta adrenoceptors in nicotine-induced hyperglycaemia in common African toad B. regularis.

Keywords: Nicotine, hyperglycaemia, prazosin, propranolol, common African toad Bufo regularis.

African Journal of Biotechnology, Vol 13(30) 3101-3106

Author Biographies

GO Isehunwa
Department of Physiology, University of Ibadan, Ibadan, Nigeria
GO Adewunmi
Department of Physiology, University of Ibadan, Ibadan, Nigeria
ARA Alada
Department of Physiology, University of Ibadan, Ibadan, Nigeria
OT Olaniyan
Department of Physiology, University of Ibadan, Ibadan, Nigeria
Published
2015-09-01
Section
Articles

Journal Identifiers


eISSN: 1684-5315