African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12193

Full Length Research Paper

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

Isehunwa, G. O.*
  • Isehunwa, G. O.*
  • Department of Physiology, University of Ibadan, Ibadan, Nigeria.
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Adewunmi, G. O.
  • Adewunmi, G. O.
  • Department of Physiology, University of Ibadan, Ibadan, Nigeria.
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Alada, A. R. A
  • Alada, A. R. A
  • Department of Physiology, University of Ibadan, Ibadan, Nigeria.
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Olaniyan, O. T.
  • Olaniyan, O. T.
  • Department of Physiology, Bingham University, Karu, Nasarawa, Nigeria.
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  •  Received: 28 February 2014
  •  Accepted: 02 June 2014
  •  Published: 23 July 2014

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.

 

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