Hayase T, Yamamoto Y, Yamamoto K, Abiru H, Fukui Y
Department of Legal Medicine, Kyoto University Faculty of Medicine, Japan.
Nihon Arukoru Yakubutsu Igakkai Zasshi. 1998 Apr;33(2):112-34.
The present study was aimed at elucidating the relationship between brain beta-endorphin, which was estimated by the immunofluorescence method, and fatal drug toxicities due to cocaine and combined cocaine-ethanol administration, including the late fatal toxicities clinically noted. beta-endorphin is an endogenous opioid peptide, and its secretion has been suggested to be influenced by physiological stresses. Furthermore, since protection against these fatal toxicities has been previously reported to be provided by buprenorphine (a ligand for opioid receptors) and Ro 15-4513 (a ligand for benzodiazepine receptors), this study also focused on the relationship between the effects of these two ligands and the changes in brain beta-endorphin immunoreactivity. In the fatal toxicity study, a toxic dose (75 mg/kg, i.p.) of cocaine combined with and without ethanol (3 g/kg, i.p.) was administered to the rats, with and without buprenorphine (0.25, 0.5, 1 mg/kg, i.p.) or Ro 15-4513 (5, 10, 15 mg/kg, i.p.). All of the deaths that occurred in these animals were divided into two groups: early deaths with early toxic symptoms in which the drugs were detected in the tissue samples, and late deaths with late toxic symptoms in which no drugs were detected in the samples. Without the administration of buprenorphine or Ro 15-4513, the frequency of late deaths was higher in the cocaine group as compared to the cocaine-ethanol group. The total mortality rate was effectively attenuated by treatment with 0.25 mg/kg buprenorphine or 10 mg/kg Ro 15-4513. Following treatment with 1 mg/kg buprenorphine or 15 mg/kg Ro 15-4513, the frequency of late deaths was significantly enhanced in the cocaine group. The brain and liver cocaethylene concentrations were also attenuated in those groups in which the total mortality rates were attenuated. In the brain beta-endorphin immunoreactivity study, the number of beta-endorphin immunoreactive nerve cells at the arcuate nucleus was counted at 3 minutes or 24 hours after the drug treatment. At 3 minutes after the drug treatment, the number of weakly immunoreactive cells with photographic light absorption values greater than 50% was enhanced in the groups in which the frequency of late deaths had been increased. In the cocaine-ethanol groups treated with buprenorphine or Ro 15-4513, this enhancement of weakly immunoreactive cells was observed when the total mortality rate was increased, regardless of the type of death. At 24 hours after the drug treatment (50 mg/kg cocaine), an enhancement of the weakly immunoreactive cells only was observed in all of the groups in which the occurrence of toxicities had been enhanced, regardless of the type of toxicity. Therefore, it can be concluded that the enhancement of total brain beta-endorphin immunoreactivity was closely correlated with the increase in the frequency of total fatal toxicities, and that the enhancement of weakly immunoreactive cells was closely correlated with the increase in the frequency of delayed fatal toxicities.
本研究旨在阐明通过免疫荧光法估算的脑β-内啡肽与可卡因及可卡因-乙醇联合给药所致致命药物毒性之间的关系，包括临床上所观察到的迟发性致命毒性。β-内啡肽是一种内源性阿片肽，其分泌被认为受生理应激影响。此外，由于先前报道丁丙诺啡（一种阿片受体配体）和Ro 15-4513（一种苯二氮䓬受体配体）可预防这些致命毒性，本研究还关注这两种配体的作用与脑β-内啡肽免疫反应性变化之间的关系。在致命毒性研究中，给大鼠腹腔注射可卡因（75 mg/kg），分别联合或不联合乙醇（3 g/kg），并分别给予或不给予丁丙诺啡（0.25、0.5、1 mg/kg，腹腔注射）或Ro 15-4513（5、10、15 mg/kg，腹腔注射）。这些动物发生的所有死亡分为两组：出现早期毒性症状的早期死亡，其组织样本中可检测到药物；出现晚期毒性症状的晚期死亡，其样本中未检测到药物。在未给予丁丙诺啡或Ro 15-4513的情况下，与可卡因-乙醇组相比，可卡因组的晚期死亡频率更高。用0.25 mg/kg丁丙诺啡或10 mg/kg Ro 15-4513治疗可有效降低总死亡率。用1 mg/kg丁丙诺啡或15 mg/kg Ro 15-4513治疗后，可卡因组的晚期死亡频率显著增加。在总死亡率降低的组中，脑和肝中可卡因乙烯的浓度也降低。在脑β-内啡肽免疫反应性研究中，在药物治疗后3分钟或24小时对弓状核中β-内啡肽免疫反应性神经细胞数量进行计数。在药物治疗后3分钟，晚期死亡频率增加的组中，光吸收值大于50%的弱免疫反应性细胞数量增加。在用丁丙诺啡或Ro 15-4513治疗的可卡因-乙醇组中，无论死亡类型如何，当总死亡率增加时，均可观察到弱免疫反应性细胞的这种增加。在药物治疗后24小时（50 mg/kg可卡因），在所有毒性发生率增加的组中，无论毒性类型如何，均仅观察到弱免疫反应性细胞增加。因此，可以得出结论，全脑β-内啡肽免疫反应性增强与总致命毒性频率增加密切相关，弱免疫反应性细胞增加与迟发性致命毒性频率增加密切相关。
