Effects of calcitonin gene-related peptide and its receptor on pain regulation in parabrachial nucleus of rats with inflammatory pain

Abstract

Inflammatory pain is one of the most common types of pain in clinical practice. The parabrachial nucleus (PBN) is involved in the development of inflammatory pain. Many studies have shown that pain is related to neurotransmitters, such as calcitonin gene-related peptide (CGRP). Carrageenan was injected into the left soles of rats to make an inflammatory pain model. CGRP and CGRP8-37 were injected into the PBN of rats. The responses to thermal and mechanical stimulation of rats were measured by hot plate and Randall Selitto tests. The expression of CLR at mRNA and protein levels was detected with RT-PCR and western blotting. Our results found that injection of CGRP resulted in an obvious antinociceptive effect in inflammatory pain rats in a dose-dependent manner. The antinociceptive effect of CGRP is significantly reduced after the injection of CGRP 8-37, suggesting that CGRP receptor is involved in the antinociceptive effect of CGRP in PBN of inflammatory rats. Furthermore, the antinociceptive effect of CGRP in inflammatory pain rats was significantly lower than that of naive rats, the expression of mRNA and protein of CLR in PBN was also decreased in inflammatory pain rats. The results showed that CGRP induced antinociception in PBN of rats with inflammatory pain and CGRP receptor involved in. Inflammatory pain resulted in decreased levels of mRNA and protein expression of CGRP receptor, and the decrease of CGRP-induced antinociception. Effects of … Lin-Lin Wang et al.