Evidence of single dose opioid dependence in 12- to 14-day-old chicken embryos.

摘要: Abstract We have previously reported that chicken embryos injected with a single dose of methadone (Meth) on day 3, 7 or 11 embryogenesis fail to show dependence 14, measured as significant overshoot in motility above baseline after challenge the opioid antagonist naloxone (Nx). Constant infusion Meth from 14 also failed produce evidence 14. To address question whether 14-day-old embryo is capable expressing withdrawal, isobutylmethylxanthine (IBMX), compound produces quasiopioid was directly into embryo, resulting increase motility. determine could express true were various doses morphine (Morph), followed at different time intervals by injections varying Nx. A high Morph 24 hours later low Nx produced did 1 hour higher U50488H, selective kappa agonist, had no effect suggesting decrease seen not mediated receptor. Pretreatment irreversible mu antagonist, beta-funaltrexamine (B-FNA), blocked and prevented when given post-Meth. able demonstrate dependence/withdrawal 12-day-old but both required. 9 led decreased 10, apparently induce broad range baseline. IBMX leading us conclude there may be sensitive period during before which this sign withdrawal cannot expressed. Because receptors are present functional even prior stage development, failure behavioral quasi-opioid 10 suggests detoxification without threat withdrawal-induced morbidity mortality attainable early stages development.