Effects of purine nucleotide administration on purine nucleotide metabolism in brains of heroin-dependent rats

ABSTRACT Heroin is known to enhance catabolism and inhibit anabolism of purine nucleotides, leading to purine nucleotide deficiencies in rat brains. Here, we determined the effect of exogenous purine nucleotide administration on purine nucleotide metabolism in the brains of heroin-dependent rats. Heroin was administrated in increasing doses for 9 consecutive days to induce addiction, and the biochemical changes associated with heroin and purine nucleotide administration were compared among the treated groups. HPLC was performed to detect the absolute concentrations of purine nucleotides in the rat brain cortices. The enzymatic activities of adenosine deaminase (ADA) and xanthine oxidase (XO) in the treated rat cortices were analyzed, and qRT-PCR was performed to determine the relative expression of ADA, XO, adenine phosphoribosyl transferase (APRT), hypoxanthine-guaninephosphoribosyl transferase (HGPRT), and adenosine kinase (AK). Heroin increased the enzymatic activity of ADA and XO, and up-regulated the transcription of ADA and XO. Alternatively, heroin decreased the transcription of AK, APRT, and HGPRT in the rat cortices. Furthermore, purine nucleotide administration alleviated the effect of heroin on purine nucleotide content, activity of essential purine nucleotide metabolic enzymes, and transcript levels of these genes. Our findings therefore represent a novel, putative approach to the treatment of heroin addiction.

摘要 海洛因已知可增强嘌呤核苷酸的分解代谢并抑制其合成代谢，进而导致大鼠脑内嘌呤核苷酸缺乏。本研究旨在探讨外源性嘌呤核苷酸给药对海洛因依赖大鼠脑内嘌呤核苷酸代谢的影响。本研究采用连续9天递增剂量海洛因给药的方式构建大鼠依赖模型，并对比各给药组中海洛因与嘌呤核苷酸联合给药相关的生化改变。采用高效液相色谱法（HPLC）检测大鼠大脑皮层内嘌呤核苷酸的绝对含量；对给药大鼠皮层中的腺苷脱氨酶（ADA）、黄嘌呤氧化酶（XO）活性进行分析，并通过实时荧光定量聚合酶链反应（qRT-PCR）检测ADA、XO、腺嘌呤磷酸核糖转移酶（APRT）、次黄嘌呤-鸟嘌呤磷酸核糖转移酶（HGPRT）以及腺苷激酶（AK）的相对表达水平。实验结果显示，海洛因可提升ADA与XO的酶活性，并上调ADA和XO的转录水平；与此同时，海洛因会降低大鼠皮层内AK、APRT及HGPRT的转录水平。进一步研究发现，外源性嘌呤核苷酸给药可缓解海洛因对嘌呤核苷酸含量、关键嘌呤核苷酸代谢酶活性以及上述基因转录水平的影响。因此，本研究结果为海洛因成瘾的治疗提供了一种全新的潜在干预策略。