Camilla Estevão de França; Carla Guardabassi & Ricardo Luiz Smith

Kinins are vasoactive peptides that promote pain and inflammation, yet centrally believed to participate to cardiovascular defensive reflexes produced by noxious stimuli. These peptides signal through the activation of two transmembrane G- protein-coupled receptors named B1 and B2 receptors (B1R and B2R). The B2R is constitutive in healthy tissues and animals. The aim of the study was to measure the gene and protein expression of B2R kinin receptors in central and peripheral tissues isolated from control 2 rats and rats were pre-treated with capsaicin on the second day of life (50 mg/kg, s.c.) or two weeks prior to sacrifice (125 mg/kg over three days, s.c.). The same treatment with saline was made in control animals. Levels of mRNA for B2R were measured by quantitative 2 RT-PCR and Qualitative while receptor binding sites were measured on tissue sections with the radioligands 125I-HPP-Hoe 140 (B R). B2R was expressed in all studied tissues (hypothalamus, paratrigeminal nucleus, nucleus of solitary tract, spinal cord, aorta and liver) and treatment capsaicin neonates when compared to controls, did not affect its level of expression. Capsaicin had no significant effect on the expression of B2R in some tissues on binding sites. The synthesis of B2R kinin receptor is not associated with sensory C-fibre and tissues showed no significant difference indicating that B2R was regulated by distinct mechanisms.

KEY WORDS: Medulla; Spinal Cord; Rats; Kinin receptor B2; Capsaicin.