Cirrhosis-induced morphological changes in the retina:possible role of endogenous opioid

·AIM: To investigate the impact of cirrhosis on retinal morphology and to evaluate the role of endogenous opioids as a mediator in cirrhosis induced retinal change.·METHODS: Thirty-six male rats were divided into 3main groups; the common bile duct ligated(BDL) group,the sham-operated(Sham) group and the unoperated(Unop) group. Then each of these three main groups was divided into two subgroups; the first subgroup received daily injection of naltrexone hydrochloride(NTX) and the second group was injected with normal saline(Saline)daily. After 28 d, rats were anesthetized and their right eyes were enucleated and assessed for histological changes. The thickness of the rod and cons layer, outer nuclear layer, outer plexiform layer, inner nuclear layer,inner plexiform layer and ganglion cell layer for each eye were measured in micrometers by light microscope.· RESULTS: Ganglion cell layer showed significant increase in thickness in the BDL group(P 【0.05). This increase was eliminated in the group where BDL rats received daily intraperitoneal injection of naltrexone hydrochloride(20 mg/kg). No other histological changes were detected in the other 5 layers we measured·CONCLUSION: The morphological change we detected in the retina of cirrhotic rats is probably due to opioids increased tone in cirrhosis since the increase in thickness in the ganglion cell layer was almost eliminated when naltrexone hydrochloride was injected.These results suggest a possible role for endogenous opioids in the morphological retinal changes detected in cirrhotic rats.

Genetics of adult attachment and the endogenous opioid system

Since the pioneering work by Panksepp et al,the neurobiological bases of attachment behavior have been closely linked with opioid neurotransmission.Candidate gene studies of adult individuals have shown that variation in the muopioid receptor gene(OPRM1)influences attachment behavior.Early maternal care and the A/A genotype of the A118G polymorphism interact in modulating levels of fearful attachment.Compared to their counterparts carrying the A/A genotype,individuals expressing the minor 118G allele show lower levels of avoidant attachment and experience more pleasure in social situations.Brain imaging research has strengthened the biological plausibility of candidate gene studies.The avoidance dimension of attachment correlates negatively with muopioid receptor availability in the thalamus and anterior cingulate cortex,as well as the frontal cortex,amygdala,and insula.Overall,findings from human studies combined with those from animal models suggest that research on the genetic bases of attachment should include the endogenous opioid system among the investigated variables.

不同参数电针对内源性阿片肽系统调节的量效关系

Endogenous opioid peptides(EOP)are the neurochemical basis of the anesthetic and analgesic effects of acupuncture,and the quantity of acupuncture stimulus can be controlled accurately by using electroacupuncture(EA).The present study explores the dose-effect relationship between EA with different parameters and the regulation of EOP system.In this paper,the intervention effects of EA on EOP system were specially discussed in terms of the single factor and the different combinations of the frequency,waveform and current intensity.This study shows that EOP system presents a frequency-response specificity.The low frequency of EA promotes the release of enkephalin,β-endorphin and endomorphin,the high one activates the dynorphin system selectively,and the intermediate frequency works on promoting the release of enkephalin andβ-endorphin,as well as dynorphin.Sparse-dense wave of EA may induce the release of enkephalin,β-endorphin,endomorphin and dynorphin,presenting a synergistic effect.However,the waveform of EA should be selected flexibly in clinical practice.Sometimes the better therapeutic effect can also be obtained with the continuous wave of EA.EOP system is involved in mediating appropriate intensity of EA,while the acupuncture effect generated by an extra strong EA stimulation refers to a kind of stress response of non-opioid mechanism.The different combinations of EA parameters result in various effects.The combination of EA parameters should be optimized in accordance with different diseases,which is valuable for guiding clinical practice and the development of EA therapy.