Citral inhibits the nociception in the rat formalin test: effect of metformin and blockers of opioid receptor and the NO-cGMP-K+ channel pathway. - Ortiz, Mario I.; Cariño-Cortés, Raquel; Muñoz-Pérez, Víctor M.; Medina-Solís, Carlo Eduardo; Castañeda-Hernández, Gilberto (Canadian Journal of Physiology & Pharmacology, 2022)