Effect of tramadol hydrochloride on neural tube development in 48-hr chick embryos: Argyrophilic nucleolar organizing region and genetic analysis study

Abstract

Background: Tramadol hydrochloride or tramadol is an opioid analgesic that acts on the central nervous system. The pregnancy category of tramadol is determined as "C" according to the Food and Drug Administration. There are no adequate and well-controlled studies in pregnant women. In this study, we aimed to reveal the effects of tramadol on neural tube (midline) closure by analyzing morphologically, histologically and genetically in chick embryos.

Methods: Ninety White Leghorn species, fertile and 0-day-old specific pathogen-free eggs (60 ± 5 g) were used in the study. Eggs were divided into a total of six groups (control, sham, and drug groups). Four different doses of tramadol (1, 2.5, 5, and 7.5 mg/egg) were administered subblastodermically at the 28th hour of the incubation. All eggs were opened at the 48th hour of incubation and evaluated.

Results: Embryos in the control group according to Hamburger-Hamilton classification were compatible with stages 13 and 14. In the groups treated with tramadol, it was determined that the embryos had neural tube closure defects (such as neck, tail regions) and some embryos showed developmental retardation due to the increase in the drug dose. In the statistical analysis performed, a significant difference was found between the control group and the group receiving the highest dose of tramadol in terms of crown-rump length and number of somites (p < .05). The brain and reproductive expression gene expression was upregulated in embryos at each of tramadol doses compared to control group.

Conclusions: It was determined that tramadol causes neural tube closure defects in embryos depending on the dose.