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Grigson, P. S.

Publications and source records attributed to Grigson, P. S..

3 recordsLinked to original sources

Acute Glucagon-Like Peptide-1 Receptor Agonist Liraglutide Prevents Drug-Induced Heroin Seeking in Rats

Substance use disorder is a difficult disease to treat due to its relapsing nature. In the last decade, opioid use disorder has been a threat to public health, being declared an epidemic by the Centers for Disease Control and Prevention. This is a tragic situation, considering there are currently effective, yet not ideal, treatments to prevent relapse. Recent research has shown that hormones that modulate hunger and satiety also can modulate motivated behavior for drugs of abuse. For example, the short-acting analog of glucagon-like peptide-1 (GLP-1), an incretin hormone that regulates homeostatic feeding, has been shown to reduce responding for rewarding stimuli such as food, cocaine, heroin and nicotine. Here, we tested the acute effects of the long-acting GLP-1 analog, liraglutide, on heroin seeking. We found that, in rats with heroin self-administration experience, subcutaneous (sc) administration of an acute dose of 0.3 mg/kg liraglutide was effective in preventing relapse after exposure to three major precipitators: drug-associated cues, stress, and the drug itself. However, the effects of the drug were contingent upon the pretreatment time, with the drug being fully effective when administered using a 6 h, rather than a 4 h pretreatment time. Finally, we confirmed that the reduction in drug seeking is not due to a locomotor impairment, as liraglutide did not significantly alter performance in a rotarod test. As such, this acute non-opioid treatment may serve as a new and effective bridge to treatment.

neuroscience↗

Adolescent social stress decrease of adult morphine-induced behavioral sensitization is dependent upon genetic background

1Deaths related to opioid use have skyrocketed in the United States, leading to a public health epidemic. Research has shown that both biological (genes) and environmental (stress) precursors are linked to opioid use. In particular, stress during adolescence - a critical period of frontal lobe development - influences the likelihood of abusing drugs. However, little is known about the biological mechanisms through which adolescent stress leads to long-term risk of opioid use, or whether genetic background moderates this response. Male and female C57BL/6J and BALB/cJ mice were exposed to chronic variable social stress (CVSS) or control conditions throughout adolescence and then tested for morphine locomotor sensitization or morphine consumption in adulthood. To examine possible mechanisms that underlie stress-induced changes in morphine behaviors, we assessed physiological changes in response to acute stress exposure and prefrontal cortex miRNA gene expression. Adolescent stress did not influence morphine sensitization or consumption in BALB/cJ animals, and there was limited evidence of stress effects in female C57BL/6J mice. In contrast, male C57BL/6J mice exposed to adolescent CVSS had blunted morphine sensitization compared to control animals; no differences were observed in the acute locomotor response to morphine administration or morphine consumption. Physiologically, C57BL/6J mice exposed to CVSS had an attenuated corticosterone recovery following an acute stressor and downregulation of twelve miRNA in the prefrontal cortex compared to control mice. The specificity of the effects for C57BL/6J versus BALB/cJ mice provides evidence of a gene by environmental interaction influencing opioid behaviors. Long-term differences in stress reactivity or miRNA expression suggests two possible biological mechanisms to evaluate in future research.

animal behavior and cognition↗

Glucagon-like peptide-1 receptor agonist, exendin-4, reduces reinstatement of heroin seeking behavior in rats

BackgroundStudies have shown that satiety agents such as exendin-4 (a glucagon-like peptide-1 analog) reduce responding for addictive drugs (e.g., cocaine, nicotine, alcohol). In this study we tested the effect of exendin-4 on cue-induced and drug-induced reinstatement of heroin seeking behavior in rats.\n\nMethodsThis study consisted of three phases: In Phase 1, 55 male Sprague-Dawley rats had 15 daily pairings of saccharin with heroin self-administration. In Phase 2, rats experienced a 16-day home cage abstinence period and daily treatment with vehicle or exendin-4. On day 17, an extinction/reinstatement test was performed to assess drug seeking. In Phase 3, rats experienced 9 days of extinction followed by a reinstatement only test. Finally, expression of mRNA for various receptors in the nucleus accumbens shell (NAcS) was measured using RTqPCR.\n\nResultsIn Phase 1, rats that avoided intake of the heroin-paired saccharin cue exhibited shorter latency to obtain the first infusion. In Phase 2, treatment with exendin-4 decreased cue-induced, but not drug-induced heroin seeking. In Phase 3, saccharin avoiders previously treated with exendin-4 increased acceptance of saccharin, and 1-hour pretreatment with Exendin-4 abolished drug-induced heroin seeking. Finally, exendin-4 treatment increased expression of mRNA for the Orexin 1 receptor (OX1) in the NAcS, but did not affect expression of dopamine D2 receptors, GLP-1 receptors, or leptin receptors in this same structure.\n\nConclusionExendin-4 reduced cue- and drug-induced heroin seeking and increased acceptance of the drug-associated saccharin cue. These changes in behavior were accompanied by an increase in the expression of the OX1 receptor in the NAcS.

animal behavior and cognition↗