{'fraction_non_alphanumeric': 0.027004909983633387, 'fraction_numerical': 0.0032733224222585926, 'mean_word_length': 5.794444444444444, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Opiate addiction: adaptations in the mesolimbic dopamine system

The mesolimbic dopamine system, which plays an important role in the reinforcingeffects of opiates reward, has been shown specific cellular adaptations in responses to chronic opiateadministration. These adaptations have been included: (1) the higher levels of tyrosine hydrox-ylase (TH), upregulation of GluR1, lower levels of neurofilament proteins and a reduction of thesize of dopamine neurons in the ventral tegmental area (VTA); (2) the functional D1-receptor su-persensitivity, decreased levels of Gi/o a subunits, increased levels of cAMP-PKA system and theupregulation of the nuclear transcription factors CREB, c-fos and c-jun expression in the nucleusaccumbens neurons. Opiates directly or indirectly alter the functional activity of the VTA-NAcdopamine system via the different actions of opioid receptors and which could producepositive reinforcement of brain rewarding system or negative effects. The administration of certainneurotrophic factors and transgenic procedures have further highlighted that these opiate-inducedadaptations of the meso-limbic DA system may be the important neural bases of the psychic de-pendence of drug addiction.