Long-Term Treatment with Buprenorphine Increased TLR1 Receptor Expression in Methamphetamine Rats' Brainstems.

Background & Objective: Toll-like receptors (TLRs) are proteins that play key roles in inflammation. METH and buprenorphine (BUP) both modulate pain, but the exact mechanism underlying their antinociceptive effects is unknown. As a result, the expression of TLR1 and TLR2 genes was examined in METH rats that had been treated with or without BUP. Materials & Methods: A total of 77 rats were classified into 11 subtypes (n = 7): control (saline), BUP 6 or 10 mg/kg, METH (10 mg/kg), METH+BUP 6 or 10 mg/kg, or withdrawal groups. The treatments were intraperitoneally administered for 5 or 14 days. RT-PCR evaluated genes expressed in the brain stem area. Results: The results showed that TLR1 gene expression in the METH group (10 mg/kg; 5 days) considerably improved compared with the control group. Furthermore, BUP injection (10 mg/kg) acutely decreased TLR2 gene expression compared with the METH group. In the METH + BUP (10 mg/kg; 14 days) group, TLR1 expression was higher than in the METH group. The coadministration of METH+BUP (10 mg/kg) acutely decreased TLR2 gene expression compared with METH. Conclusion: There are limited changes in these genes, and their role in METH consumption and inflammation is unclear. Due to the presence of these two genes in the inflammatory pain and addiction signaling pathways, they may have more clear roles in other parts of the nervous system. [ABSTRACT FROM AUTHOR]