mRNA levels of kinin B1 and B2 receptors were determined in HPA axis of type 1 (STZ-induced) and type 2 diabetic rats (ZDF and obese Zucker rats). B2 mRNA levels were elevated in hypothalamus of STZ-induced diabetic (STZ-D) and ZDF rats. Pituitary B2 mRNA levels were elevated in ZDF and obese rats. Adrenal B2 mRNA level was attenuated in STZ-D rats. Kinin B1 receptor may not play a role in HPA axis in diabetes since its expression was unchanged. Enhanced mRNA expression of B2 receptors in hypothalamus of STZ-D and ZDF rats parallels a rise in plasma glucose and reflect a functional relationship. Enhanced pituitary B2 mRNA in type 2 and reduced adrenal in type 1 diabetes account for a differential pattern in release of transmitters.