| 1. |
- Brolin, Erika, et al.
(författare)
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Chronic administration of morphine using mini-osmotic pumps affects spatial memory in the male rat
- 2018
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Ingår i: Pharmacology, Biochemistry and Behavior. - : Elsevier BV. - 0091-3057 .- 1873-5177. ; 167, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- The use of opioid analgesics to treat non-cancer pain has increased over the years. Many chronic pain patients suffer from numerous adverse effects, such as reduced quality of life, development of dependence, and cognitive impairments. Cognitive processes are regulated by several systems, one of which involves growth hormone (GH) and its secondary mediator insulin-like growth factor-1 (IGF-1), but also glutamatergic transmission, including receptors such as the N-methyl-D-aspartate (NMDA)-receptor complex. In the laboratory, repeated injections are commonly used to establish animal models of long-term or chronic drug exposure. However, in the present study, we aimed to mimic a more human dose regimen using constant drug delivery provided by mini-osmotic pumps implanted subcutaneously in male Sprague Dawley rats. After developing opioid tolerance the cognitive function of rats was studied. Spatial learning and memory capabilities were evaluated using the rat Morris water maze (MWM). Moreover, gene expression related to the GH/IGF-1-axis and the NMDA-receptor system was analyzed using quantitative PCR (qPCR) and plasma levels of IGF-1 were assessed using the ELISA technique. Our results demonstrate that rats exposed to morphine for 27 days display memory impairments in the MWM probe trial. However, the behavioral effects of chronic morphine treatment were not accompanied by any significant differences in terms of mRNA expression or IGF-1 plasma concentration. The animal model used in this study provides a simple and suitable way to investigate the behavioral and neurochemical effects of chronic opioid treatment similar to the exposure seen in human pain patients.
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| 2. |
- Nylander, Erik, 1986-, et al.
(författare)
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The Protective and Restorative Effects of Growth Hormone and Insulin-Like Growth Factor-1 on Methadone-Induced Toxicity In Vitro
- 2018
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 19:11, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- Evidence to date suggests that opioids such as methadone may be associated with cognitive impairment. Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are suggested to be neuroprotective and procognitive in the brain and may therefore counteract these effects. This study aims to explore the protective and restorative effects of GH and IGF-1 in methadone-treated cell cultures. Primary cortical cell cultures were harvested from rat fetuses and grown for seven days in vitro. To examine the protective effects, methadone was co-treated with or without GH or IGF-1 for three consecutive days. To examine the restorative effects, methadone was added for the first 24 h, washed, and later treated with GH or IGF-1 for 48 h. At the end of each experiment, mitochondrial function and membrane integrity were evaluated. The results revealed that GH had protective effects in the membrane integrity assay and that both GH and IGF-1 effectively recovered mitochondrial function and membrane integrity in cells pretreated with methadone. The overall conclusion of the present study is that GH, but not IGF-1, protects primary cortical cells against methadone-induced toxicity, and that both GH and IGF-1 have a restorative effect on cells pretreated with methadone.
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