Serum transforming growth factor β concentrations in streptozotocin and insulin resistant diabetic female rats during phases of the estrous cycle

  • A.P. Arikawe
  • I.C. Udenze
  • A.O. Ogunsola
  • K.A. Dada
  • T.E. Ogundeko
Keywords: Diabetes, insulin resistance, inhibin B, activin A, gonadotropins


Background: Transforming Growth Factors beta (TGF-β) are proteins that function in most cells to promote cellular proliferation and differentiation.

Objective: inhibin and activin are example of TGF-β involved in the regulation of pituitary gonadotrophin secretion, however precise implications of this involvement in female diabetic and insulin resistant rats is less understood.

Methods: Female Sprague-Dawley rats aged 6 weeks were divided into 3 groups. Control; Streptozotocin (STZ) group received single IP injection of STZ 45 mg/kg body weight in Na+ citrate buffer pH 4.5; Insulin resistant (IR) group fed on a diet containing 25% fructose weight for weight. Estrous cycle was monitored and during each phase, blood samples were collected by cardiac puncture under tribromoethanol anaesthesia (250mg/kg) for measurement of serum activin A and inhibin B concentrations using ELISA method.

Results: The STZ and IR groups recorded irregular estrous cycle pattern with prolonged proestrus, metestrus, diestrus phases and a significantly reduced (P < 0.05) estrus phase compared to the control group. Inhibin B was significantly lower (P < 0.05) in experimental groups compared to control. Activin A was significantly higher (P < 0.05) in IR group compared to the Control and STZ groups during proestrus and metestrus phases while it was significantly lower (P < 0.05) in the IR group compared to the Control and STZ groups during estrus and diestrus phases of the estrous cycle.

Conclusion: Our result showed that diabetes mellitus and insulin resistance altered normal levels of TGF-β in female rats. These open a new prospect to study hormonal profile and hypothalamopituitary-ovarian axis in insulin resistant diabetic female rats with a view to identify neuroendocrine centres that might be implicated.

Keywords: Diabetes, insulin resistance, inhibin B, activin A, gonadotropins


Journal Identifiers

eISSN: 0189-2657