Cholestasis induced antinociception and decreased gene expression of MOR1 in rat brain

Modulation of social and depression behaviors in cholestatic and drug-dependent mice: possible role of opioid receptors

Objectives

Social behavior, a set of motivating activities critical for survival, is disturbed in cholestasis conditions and many substance abusers as well as psychiatric disorders. The documented loss of social interest in cholestatic patients may be associated with depressive symptoms. Interestingly, the endogenous opioid system is involved in the modulation of depression.

Methods in this research

, we assessed the effect of cholestasis and drug dependence on social and depression behaviors using the Three-Chamber Paradigm Test, Forced Swim Test (FST), and Tail Suspension Test (TST) as well as Open Field Test (OFT) in male NMRI mice.

Results

The results indicated that alone administration of morphine and tramadol, as well as co-administration of them, increased social motivation and novelty but decreased depression in bile duct ligated mice. Whereas, alone administration of naloxone (a µ-opioid receptor antagonist) and co-administration of it along with morphine and tramadol decreased social motivation and novelty while enhanced depression in the sham-operated and bile duct ligated mice. These administrations of drugs did not change locomotor activity compared to the control group.

Conclusion

In conclusion, it appears that (i) both cholestasis and drug dependence impaired social motivation behavior, as well as induced depression-like behavior in the bile duct, ligated mice, (ii) alone administration of morphine and tramadol as well as co-treatment of them may protect against cholestasis and drug dependence induced abnormal behaviors, (iii) µ-opioid receptors play an important role in modulation of social motivation and depression behaviors in mice.

Repeated Use of Morphine Induces Anxiety by Affecting a Proinflammatory Cytokine Signaling Pathway in the Prefrontal Cortex in Rats

We examined the role of toll-like receptors (TLRs) and proinflammatory cytokine signaling pathways in the prefrontal cortex (PFC) in anxiety-like behaviors after repeated use of morphine. Morphine (10 mg/kg) was used twice daily for 8 days to induce morphine dependence in male Wistar rats. On day 8, opioid dependence was confirmed by measuring naloxone-precipitated withdrawal signs. On days 1 and 8, anxiety-like behaviors were evaluated using a light/dark box test. Expression of TLR1 and 4, proinflammatory cytokines, and some of the downstream signaling molecules was also evaluated in the bilateral PFC at mRNA and protein levels following morphine dependence. The results revealed that morphine caused anxiolytic-like effects on day 1 while induced anxiety following 8 days of repeated injection. On day 8, a significant decrease in TLR1 expression was detected in the PFC in morphine-dependent rats, but TLR4 remained unaffected. Repeated morphine injection significantly increased IL1-β, TNFα, and IL6 expression, but decreased IL1R and TNFR at mRNA and protein levels except for IL6R at the protein level in the PFC. The p38α mitogen-activated protein (MAP) kinase expression significantly increased but the JNK3 expression decreased in the PFC in morphine-dependent rats. Repeated injection of morphine also significantly increased the NF-κB expression in the PFC. Further, significant increases in Let-7c, mir-133b, and mir-365 were detected in the PFC in morphine-dependent rats. We conclude that TLR1 and proinflammatory cytokines signaling pathways in the PFC are associated with the anxiogenic-like effects of morphine following its chronic use in rats via a MAP kinase/NF-κB pathway.

Differential expression of H19, BC1, MIAT1, and MALAT1 long non-coding RNAs within key brain reward regions after repeated morphine treatment

Morphine-induced analgesic tolerance and dependence are significant limits of pain control; however, the exact molecular mechanisms underlying morphine tolerance and dependence have remained unclear. The role of long non-coding RNAs (lncRNAs) in morphine tolerance and dependence is yet to be determined. We aimed to explore the association of specific lncRNAs expression in key brain reward regions after repeated injection of morphine. Male Wistar rats received subcutaneous injections of twice-daily morphine (10 mg/kg) or saline (1 mL/kg) for eight days. On day 8 of the repeated injections, induction of morphine analgesic tolerance and dependence was confirmed through a hotplate test and a naloxone-precipitated withdrawal analysis, respectively. Expression of H19, BC1, MIAT1, and MALAT1 lncRNAs was determined from the midbrain, striatum, hypothalamus, prefrontal cortex (PFC), and hippocampus by real-time PCR on day 8 of the repeated injections. The H19 expression was significantly different between morphine-treated and control saline-treated rats in all investigated areas except for the hippocampus. The BC1 expression significantly altered in the midbrain, hypothalamus, and hippocampus, but not in the striatum and PFC after repeated morphine treatment. The MIAT1 and MALAT1 expression site-specifically altered in the midbrain, hypothalamus, and striatum; however, no significant changes were detected in their expression in the PFC and hippocampus after repeated morphine treatment. We conclude that alterations in the expression of these lncRNAs in the brain reward regions especially in the midbrain, striatum and hypothalamus may have critical roles in the development of morphine dependence and tolerance, which need to be considered in future researches.

Possible involvement of the opioidergic system in the modulation of body temperature, jumping behavior and memory process in cholestatic and addicted mice

Cholestasis is related to an increased plasma level of endogenous opioid levels. Naloxone-induced withdrawal syndrome has been reported in a mouse model of cholestasis. Moreover, studies revealed that the memory process is affected by cholestasis. Thus, we aimed at determining whether pharmacological manipulation of the opioidergic system is involved in signs of cholestasis disease such as hypothermia and withdrawal behaviors such as jumping behavior as well as memory process in mice. Cholestasis was induced by bile duct resection in mice and physical dependence was induced by administration of morphine and/or tramadol three times daily (8, 12 and 16 h) at the doses of 25, 50 and 75 mg/kg during three consecutive days. The memory process was assessed by a step-down passive avoidance test. Our results indicated that cholestatic mice showed hypothermia whereas cholestatic- and drug dependent mice indicated hyperthermia. Moreover, administration of morphine (50 mg/kg) and/or tramadol (50 mg/kg) on the 4th day, 2 h before naloxone injection significantly decreased latency to first jumping but increased the number of jumping and rearing behavior as well as locomotor activity in BDL-vs. sham-operated mice. In addition, the latency time of the step-down test decreased in BDL-vs. sham-operated group, showing impairment of memory in BDL mice. The results of this study support the evidence that (1) the opioidergic system involved in thermoregulation of cholestasis mice, (2) μ-opioid receptors play an important role in withdrawal behaviors, and (3) memory process is affected by cholestasis and addiction in mice.

Anxiety in rats with bile duct ligation is associated with activation of JNK3 mitogen-activated protein kinase in the hippocampus

We examine the anxiety-like behaviors in rats with bile duct ligation (BDL), as well as its relationship with the expression of JNK3 and P38 MAPKs in rat hippocampus. Male Wistar rats undergo either sham operation or BDL as a rat model of cirrhotic HE. The anxiety-like behaviors are determined using a light/dark box test two hours befor the surgery on day 1 and on days 7, 14, 21 and 28 of BDL. The gene and protein expression levels of JNK3 and p38 in the hippocampus were examined respectively with qPCR and western blotting methods on day 28 of BDL. The results revealed that anxiety was increased in the cirrhotic HE model rats during 28 days of BDL. The molecular data indicated that the gene expression of Jnk3 and protein levels of JNK3, as well as phospho-JNK3, significantly increased in the hippocampus of the cirrhotic HE model rats compared to the sham control group. However, the results revealed no significant changes in the gene expression and the protein levels of p38 as well as phospho-p38 in the hippocampus of the cirrhotic HE model rats compared to the sham control group. We conclude that the increases in the expression and activation of JNK3 MAPK in the hippocampus may underlie, at least partly, the anxiety-like behaviors in rats with cirrhotic HE.

Altered expression of itch‑related mediators in the lower cervical spinal cord in mouse models of two types of chronic itch

In this study, we focused on several itch-related molecules and receptors in the spinal cord with the goal of clarifying the specific mediators that regulate itch sensation. We investigated the involvement of serotonin receptors, opioid receptors, glia cell markers and chemokines (ligands and receptors) in models of acetone/ether/water (AEW)- and diphenylcyclopropenone (DCP)-induced chronic itch. Using reverse transcription-quantitative polymerase chain reaction, we examined the expression profiles of these mediators in the lower cervical spinal cord (C5-8) of two models of chronic itch. We found that the gene expression levels of opioid receptor mu 1 (Oprm1), 5-hydroxytryptamine receptor 1A (Htr1a) and 5-hydroxytryptamine receptor 6 (Htr6) were upregulated. Among the chemokines, the expression levels of C-C motif chemokine ligand (Ccl)21, Cxcl3 and Cxcl16 and their receptors, Ccr7, Cxcr2 and Cxcr6, were simultaneously upregulated in the spinal cords of the mice in both models of chronic itch. By contrast, the expression levels of Ccl2, Ccl3, Ccl4 and Ccl22 were downregulated. These findings indicate that multiple mediators, such as chemokines in the spinal cord, are altered and may be central candidates in further research into the mechanisms involved in the development of chronic itch.

Altered Expression of Differential Genes in Thoracic Spinal Cord Involved in Experimental Cholestatic Itch Mouse Model

The spinal origin of cholestatic itch in experimental obstructive jaundice mouse model remains poorly understood. In this study, the jaundice model was established by bile duct ligation (BDL) in mice, and differential gene expression patterns were analyzed in the lower thoracic spinal cord involved in cholestatic pruritus after BDL operation using high-throughput RNA sequencing. At 21st day after BDL, the expression levels of ENSRNOG00000060523, ENSRNOG00000058405 and ENSRNOG00000055193 mRNA were significantly up-regulated, and those of ENSRNOG00000042197, ENSRNOG00000008478, ENSRNOGOOOOOO19607, ENSRNOG00000020647, ENSRNOG00000046289, Gemin8, Serpina3n and Trim63 mRNA were significantly down-regulated in BDL group. The RNAseq data of selected mRNAs were validated by RT-qPCR. The expression levels of ENSRNOG00000042197, ENSRNOG00000008478, ENSRNOGOOOOOO 19607, ENSRNOG00000020647, ENSRNOG00000046289 and Serpina3n mRNA were significantly down-regulated in BDL group. This study suggested that cholestatic pruritus in experimental obstructive jaundice mouse model is related with in the changes of gene expression profiles in spinal cord.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Peripheral and spinal 5-HT receptors participate in cholestatic itch and antinociception induced by bile duct ligation in rats

Although 5-HT has been implicated in cholestatic itch and antinociception, two common phenomena in patients with cholestatic disease, the roles of 5-HT receptor subtypes are unclear. Herein, we investigated the roles of 5-HT receptors in itch and antinociception associated with cholestasis, which was induced by common bile duct ligation (BDL) in rats. 5-HT-induced enhanced scratching and antinociception to mechanical and heat stimuli were demonstrated in BDL rats. 5-HT level in the skin and spinal cord was significantly increased in BDL rats. Quantitative RT-PCR analysis showed 5-HT_1B, 5-HT_1D, 5-HT_2A, 5-HT_3A, 5-HT_5B, 5-HT₆, and 5-HT₇ were up-regulated in peripheral nervous system and 5-HT_1A, 5-HT_1F, 5-HT_2B, and 5-HT_3A were down-regulated in the spinal cord of BDL rats. Intradermal 5-HT₂, 5-HT₃, and 5-HT₇ receptor agonists induced scratching in BDL rats, whereas 5-HT₃ agonist did not induce scratching in sham rats. 5-HT_1A, 5-HT₂, 5-HT₃, and 5-HT₇ agonists or antagonists suppressed itch in BDL rats. 5-HT_1A agonist attenuated, but 5-HT_1A antagonist enhanced antinociception in BDL rats. 5-HT₂ and 5-HT₃ agonists or antagonists attenuated antinociception in BDL rats. Our data suggested peripheral and central 5-HT system dynamically participated in itch and antinociception under cholestasis condition and targeting 5-HT receptors may be an effective treatment for cholestatic itch.

Hepatic encephalopathy induces site-specific changes in gene expression of GluN1 subunit of NMDA receptor in rat brain

We investigate changes in gene expression of GluN1 subunit of N-Methyl-D-Aspartate (NMDA) receptor in the prefrontal cortex (PFC), hippocampus and striatum in a rat model of hepatic encephalopathy (HE). We used male Wistar rats in which HE was induced after a common bile duct ligation (BDL). The animals were divided into three sets, and each set included three groups of control, sham operated and BDL. In the first set of animals, blood samples collected for biochemical analysis on day 21 of BDL. In the second set, changes in nociception threshold was assessed on day 21 of BDL using a hotplate test. In the third set, whole brain extracted, and the PFC, the hippocampus and the striatum in each rat were immediately dissected. We used a semi-quantitative RT-PCR method for evaluating the GluN1 gene expression. The biochemical analyses showed that plasma levels of ammonia and bilirubin in BDL rats were significantly increased compared to the sham control group on day 21 of BDL (P < 0.01). Nociception threshold was also increased in rats with BDL compared to sham group (P < 0.001). The results revealed that the GluN1 gene expression at mRNA levels in BDL group was decreased by 19 % in the PFC (P < 0.05) but increased by 82 % in the hippocampus (P < 0.01) compared to the sham control group; however, no significant change was observed in the striatum. It can be concluded that HE affects the GluN1 gene expression in rat brain with a site-specific pattern, and the PFC and hippocampus are more sensitive areas than striatum.

Cholestatic liver injury model of bile duct ligation and the protection of Huang-Lian-Jie-Du decoction by NMR metabolomic profiling

Bile duct ligation (BDL) induced cholestasis in rats and the treatment effects of Huang-Lian-Jie-Du decoction (HLJDD) were investigated by NMR-based metabolomics approach: biphasic feature of BDL model and bilateral adjustment of HLJDD were found.