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. 2023 Feb 15;28(4):1822. doi: 10.3390/molecules28041822

Figure 4.

Figure 4

Characterization of OL-CTOP antinociception and antagonism of morphine in the 55 °C warm-water tail-withdrawal assay. (A) Control comparison with CTOP itself. Intracerebroventricular pretreatment with parent peptide CTOP (637 μg, i.c.v.; black bar) antagonized the response of morphine (10 nmol, i.c.v.; blue bar), whereas intranasal (i.n.s.) administration of CTOP (600 μg, i.n.s.; white bar) was without effect. * p < 0.0001 vs. morphine (Tukey test). Data shown are tail withdrawal latencies (as means ± SEM) from eight mice, with results from 24 mice overall. (B) Mice treated intranasally (i.n.s.) with OL-CTOP (100, 300 or 600 μg) showed a modest increase in tail-withdrawal latency over baseline up to 30 min post administration (left panel). All mice pretreated with OL-CTOP (30 μg (not shown in the left panel) 100, 300 or 600 μg) were then administered morphine (10 nmol, i.c.v.) 55 min after OL-CTOP administration, and the tail-withdrawal latency was measured 20, 30 or 40 min afterward (right panel). Control mice received morphine alone (blue circles). Data shown are tail withdrawal latencies (as means ± SEM) from five to eight mice, with results from 34 mice overall.