Animal experiment:

Rats: Adult male Sprague Dawley rats are given a spinal hemisection or a sham surgery at the T13 spinal segment. An externally accessible PE-10 intrathecal catheter that terminated at T13 is used for drug delivery. Animals are allowed to recover for 4 weeks at which time the hemisected animals displayed mechanical and thermal allodynia bilaterally, in both forelimbs and hindlimbs. CGRP-(8-37) is delivered just prior to a testing session in 1, 5, 10, or 50 nM doses in artificial cerebral spinal fluid in 10 mL volumes[1].

Rat CGRP-(8-37) (VTHRLAGLLSRSGGVVKDNFVPTNVGSEAF) is a highly selective CGRP receptor antagonist.

CGRP-(8-37) is a truncated version of calcitonin gene-related peptide (CGRP) that binds to the CGRP receptor with similar affinity but does not activate the receptor[1].

CGRP-(8-37) is effective in alleviating mechanical and thermal allodynia in a dose-dependent manner. The 50 nM dose is most efficacious for both forelimb and hindlimb responses. The period of efficacy is 10 min to onset for a duration of 20 min. Post-drug washout responses are not statistically significant compared to pre-drug responses[1]. Intrathecal administration of 5 nmol or 10 nmol of CGRP-(8-37), but not 1 nmol, induces a significant increase in hindpaw withdrawal latency. Intrathecal administration of CGRP-(8-37) not only reverses the SP-induced decrease in latency to both withdrawal responses but also mediates a significant increase in response latency compared to basal levels[2].

References:
[1]. Bennett AD, et al. Alleviation of mechanical and thermal allodynia by CGRP(8-37) in a rodent model of chroniccentral pain. Pain. 2000 May;86(1-2):163-75.
[2]. Yu LC, et al. The calcitonin gene-related peptide antagonist CGRP8-37 increases the latency to withdrawalresponses in rats. Brain Res. 1994 Aug 8;653(1-2):223-30.