Using in vitro receptor autoradiography, this study aims at determining whether the higher level of kinin B₂ receptor density in the spinal cord of SHR is secondary to arterial hypertension, and if chronic treatment with angiotensin-1 converting enzyme inhibitors (ACEI) can regulate neuronal B₁ and B₂ receptors. SHR received from the age of 4 weeks, one of the two ACEI (lisinopril or zofenopril, 10 mg/kg/day ) or for comparison, the selective AT₁ antagonist (losartan, 20 mg/kg/day) in their drinking water for a period of 4, 12 and 20 weeks. Age-matched untreated SHR and Wistar Kyoto rats (WKY) were used as controls. B₂ receptor binding sites in most laminae were higher in SHR than in WKY from the age of 8 to 24 weeks. While B₁ receptor binding sites were significantly present in young SHR and WKY, they were barely detectable in adults. ACEI (16 and 24 weeks) and AT₁ antagonist (24 weeks) enhanced the number of B₂ without changing B₁ receptor binding sites. However, at 8 weeks the three treatments significantly increased B₁ and decreased B₂ receptors in lamina I. It is concluded that I) the higher density of B₂ receptors in the spinal cord of SHR is not due to hypertension, 2) kinin receptors are regulated differently by ACEI in neuronal and vascular tissues, and 3) ageing may have a profound impact on levels of B₁ and B₂receptors in the rat spinal cord.