Dataset Information

Changes in Monoaminergic Neurotransmission in an Animal Model of Osteoarthritis: The Role of Endocannabinoid Signaling.

ABSTRACT: Chronic pain is a main symptom of osteoarthritis (OA). Moreover, a high percentage of OA patients suffer from mental health problems. The endocannabinoid (EC) system has attracted attention as an emerging drug target for pain treatment together with its activity on the mesolimbic reward system. Understanding the circuits that govern the reward of pain relief is crucial for the search for effective analgesics. Therefore, we investigated the role of the EC system on dopamine (DA) and noradrenaline (NA) in an animal model of OA-related chronic pain. OA rats exhibited significant decreases in DA metabolism in the nucleus accumbens (NAc), striatum (STR) and hippocampus (HC). NA metabolism was also significantly decreased by chronic pain in OA rats; however, this disruption was limited to the frontal cortex (FCx) and HC. URB597 (an inhibitor of EC metabolism) treatment completely reversed the decreased DA metabolism, especially in the brain reward system and the HC. Furthermore, administration of URB597 normalized the impairment of NA activity in the HC but potentiated the decreased NA levels in the FCx. Our results demonstrated that chronic pain in OA rats was reflected by the inhibition of mesolimbic and mesocortical dopaminergic transmission, and may indicate the pro-pain role of NA in the FCx. The data provide understanding about changes in neurotransmission in chronic pain states and may explain the clinical improvement in perceived life quality following cannabinoid treatment. Additional mechanistic studies in preclinical models examining the intersection between chronic pain and reward circuits may offer new approaches for improving pain therapy.

SUBMITTER: Mlost J

PROVIDER: S-EPMC6306412 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Changes in Monoaminergic Neurotransmission in an Animal Model of Osteoarthritis: The Role of Endocannabinoid Signaling.

Mlost Jakub J Wąsik Agnieszka A Michaluk Jerzy Tadeusz JT Antkiewicz-Michaluk Lucyna L Starowicz Katarzyna K

Frontiers in molecular neuroscience 20181220

Chronic pain is a main symptom of osteoarthritis (OA). Moreover, a high percentage of OA patients suffer from mental health problems. The endocannabinoid (EC) system has attracted attention as an emerging drug target for pain treatment together with its activity on the mesolimbic reward system. Understanding the circuits that govern the <i>reward</i> of <i>pain relief</i> is crucial for the search for effective analgesics. Therefore, we investigated the role of the EC system on dopamine (DA) and ...[more]

PMID: 30618615

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Project description:Background and purposeAlthough the antinociceptive efficacies of imidazoline I2 receptor agonists have been established, the exact post-receptor mechanisms remain unknown. This study tested the hypothesis that monoaminergic transmission is critical for I2 receptor agonist-induced antinociception.Experimental approachvon Frey filaments were used to assess antinociceptive effects of two I2 receptor agonists, 2-BFI and CR4056 on chronic constriction injury (CCI)-induced neuropathic pain or complete Freund's adjuvant (CFA)-induced inflammatory pain in rats. Rectal temperature was measured to assess hypothermic effects of 2-BFI. A two-lever drug discrimination paradigm in which rats were trained to discriminate 5.6 mg·kg-1 2-BFI (i.p.) from its vehicle was used to examine the discriminative stimulus effects of 2-BFI. In each experiment, pharmacological mechanisms were investigated by combining 2-BFI or CR4056 with various pharmacological manipulations of the monoaminergic system including selective reuptake inhibition, monoamine depletion and monoamine receptor antagonism.Key resultsIn the CCI model, selective reuptake inhibitors of 5-HT (fluoxetine) or noradrenaline (desipramine), but not dopamine (GBR12909), enhanced 2-BFI-induced antinociception. Selective depletion of 5-HT or noradrenaline almost abolished 2-BFI-induced antinociception. 5-HT1A , 5-HT2A and α1 -adrenoceptor antagonists, but not other monoaminergic antagonists, attenuated 2-BFI and CR4056-induced antinociception in CCI and/or CFA models. However, none of these monoamine receptor antagonists significantly altered 2-BFI-induced hypothermia or discriminative stimulus effects.Conclusions and implicationsAntinociception induced by I2 receptor agonists was mediated by serotonergic and noradrenergic mechanisms with 5-HT1A , 5-HT2A and α1 -adrenoceptor being particularly important. In contrast, the hypothermic and discriminative stimulus effects of I2 receptor agonists were mediated by distinct, independent mechanisms.

Project description:Background Longitudinal data on the association of quantitative thigh muscle MRI markers with knee osteoarthritis (KOA) outcomes are scarce. These associations are of clinical importance, with potential use for thigh muscle-directed disease-modifying interventions. Purpose To measure KOA-associated longitudinal changes in MRI-derived muscle cross-sectional area (CSA) and adipose tissue and their association with downstream symptom worsening and knee replacement (KR). Materials and Methods In a secondary analysis of the Osteoarthritis Initiative multicenter prospective cohort (February 2004 through October 2015), knees of participants with available good-quality thigh MRI scans at baseline and at least one follow-up visit were included and classified as with and without KOA according to baseline radiographic Kellgren-Lawrence grade of 2 or higher and matched for confounders with use of propensity score matching. An automated deep learning model for thigh MRI two-dimensional segmentation was developed and tested. Markers of muscle CSA and intramuscular adipose tissue (intra-MAT) were measured at baseline and 2nd- and 4th-year follow-up (period 1) and compared between knees with and without KOA by using linear mixed-effect regression models. Furthermore, in knees with KOA, the association of period 1 changes in muscle markers with risk of KR (Cox proportional hazards) and symptom worsening (mixed-effect models) during the 4th to 9th year (period 2) was evaluated. Results This study included 4634 matched thighs (2317 with and 2317 without KOA) of 2344 participants (mean age, 62 years ± 9 [SD]; 1292 women). Compared with those without, knees with KOA had a decrease in quadriceps CSA (mean difference, -8.21 mm2/year; P = .004) and an increase in quadriceps intra-MAT (1.98 mm2/year; P = .007). Decreased CSA and increased intra-MAT of quadriceps during period 1 was predictive of downstream (period 2) KOA symptom worsening (Western Ontario and McMaster Universities Osteoarthritis Index total score: odds ratio, 0.24 [negative association] [P < .001] and 1.38 [P = .012], respectively). Quadriceps CSA changes were negatively associated with higher future KR risk (hazard ratio, 0.70; P < .001). Conclusion Knee osteoarthritis was associated with longitudinal MRI-derived decreased quadriceps cross-sectional area and increased intramuscular adipose tissue. These potentially modifiable risk factors were predictive of downstream symptom worsening and knee replacement. Clinical trial registration no. NCT00080171 © RSNA, 2022 Online supplemental material is available for this article.

Dataset Information

Changes in Monoaminergic Neurotransmission in an Animal Model of Osteoarthritis: The Role of Endocannabinoid Signaling.

Publications

Changes in Monoaminergic Neurotransmission in an Animal Model of Osteoarthritis: The Role of Endocannabinoid Signaling.

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