Browsing by Author "Ko, Ashley"
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Item Open Access Amitifadine, a triple reuptake inhibitor, reduces self-administration of the opiate remifentanil in rats.(Psychopharmacology, 2020-06) Levin, Edward D; Wells, Corinne; Hawkey, Andrew; Holloway, Zade; Blair, Graham; Vierling, Alexander; Ko, Ashley; Pace, Caroline; Modarres, John; McKinney, Anthony; Rezvani, Amir H; Rose, Jed ERationale
A variety of neural systems are involved in drug addiction, and some of these systems are shared across different addictive drugs. We have found several different types of drug treatments that successfully reduce nicotine self-administration.Objectives
The current set of studies is the first in a series to determine if drug treatments that have been found to significantly reduce nicotine self-administration would reduce opiate self-administration.Methods
Amitifadine, a triple reuptake inhibitor of dopamine, norepinephrine, and serotonin, was assessed in female Sprague-Dawley rats to determine whether it significantly reduces remifentanil self-administration with either acute or chronic treatment.Results
Acutely, amitifadine doses of 5, 10, and 20 mg/kg each significantly reduced remifentanil self-administration. In a chronic study, repeated treatment with 10 mg/kg of amitifadine continued to reduce remifentanil self-administration, even after the cessation of treatment. However, amitifadine was not found to attenuate the rise in remifentanil self-administration with continued access. This study and our earlier one showed that the 10 mg/kg amitifadine dose did not significantly affect food motivated responding. Amitifadine did not attenuate remifentanil-induced antinociception as measured on the hot plate test but extended and maintained antinociceptive effects.Conclusions
These studies show the promise of amitifadine as a treatment for countering opiate self-administration for adjunctive use with opioids for analgesia. Further studies are needed to determine the possible efficacy of amitifadine for combating opiate addiction or preventing it in humans during adjunctive use with opioids for chronic pain.Item Open Access Correction to: Amitifadine, a triple reuptake inhibitor, reduces self-administration of the opiate remifentanil in rats.(Psychopharmacology, 2021-04) Levin, Edward D; Wells, Corinne; Hawkey, Andrew; Holloway, Zade; Blair, Graham; Vierling, Alexander; Ko, Ashley; Pace, Caroline; Modarres, John; McKinney, Anthony; Rezvani, Amir H; Rose, Jed EOur article published in Psychopharmacology had a typographical error in the units of remifentanil infusion for selfadministration. The correct infusion dose of remifentanil is 0.3 µg/kg/infusion not 0.3 mg/kg/infusion.Item Open Access Corrigendum to "The Developmental Neurotoxicity of Tobacco Smoke Can Be Mimicked by a Combination of Nicotine and Benzo[a]pyrene: Effects on Cholinergic and Serotonergic Systems".(Toxicological sciences : an official journal of the Society of Toxicology, 2019-03) Slotkin, Theodore A; Skavicus, Samantha; Ko, Ashley; Levin, Edward D; Seidler, Frederic JThe correct units in Tables S3, S5, and S6 are "fmol/mg protein," whereas no units should be specified in Table S4, which presents data as a ratio.Item Open Access Dextromethorphan and bupropion reduces high level remifentanil self-administration in rats.(Pharmacology, biochemistry, and behavior, 2020-04) Blair, Graham; Wells, Corinne; Ko, Ashley; Modarres, John; Pace, Caroline; Davis, James M; Rezvani, Amir H; Rose, Jed E; Levin, Edward DOpiate addiction has risen substantially during the past decade. New treatments to combat opiate addiction are sorely needed. The current study was conducted to determine the acute individual and interactive effects of bupropion and dextromethorphan in a rat model of opiate self-administration using the short-acting synthetic opioid remifentanil. Both of these drugs have been found to reduce self-administration of nicotine. Bupropion and dextromethorphan and their combination had differential effects depending on whether the rats showed higher or lower baseline remifentanil self-administration. The rats with higher initial remifentanil self-administration showed a significant decrease in remifentanil self-administration with bupropion or dextromethorphan treatment, compared to the vehicle control condition. This decrease in self-remifentanil administration was most pronounced when combination of the higher doses of bupropion and dextromethorphan were administered. In contrast, the rats with lower baseline remifentanil self-administration showed the opposite effect of drug treatment with an increase in remifentanil self-administration with bupropion treatment compared to the vehicle control condition. Dextromethorphan had no significant effect inthis group. This study shows that combination bupropion and dextromethorphan affects remifentanil self-administration in a complex fashion with differential effects on low and high baseline responders. In subjects with high baseline remifentanil self-administration, bupropion and dextromethorphan treatment significantly reduced self-administration, whereas in subjects with low baseline remifentanil self-administration, bupropion increased remifentanil self-administration and dextromethorphan had no discernible effect. This finding suggests that combination bupropion-dextromethorphan should be tested in humans, with a focus on treating people with high-level opiate use.Item Open Access Differential behavioral functioning in the offspring of rats with high vs. low self-administration of the opioid agonist remifentanil.(European journal of pharmacology, 2021-10) Rezvani, Amir H; Wells, Corinne; Hawkey, Andrew; Blair, Graham; Koburov, Reese; Ko, Ashley; Schwartz, Andrea; Kim, Veronica J; Levin, Edward DOpioid use disorder (OUD) has a variety of adverse effects on both the users and their offspring. In the current study, a random group of Sprague-Dawley rats (25 females and 15 males) were tested for intravenous self-administration of the opioid agonist remifentanil to determine the range of acquisition for opioid. One-month after the end of self-administration of remifentanil, rats with the highest intake were mated together and rats with lowest intake were mated together. Then, the offspring of the two groups were tested for anxiety-like behavior, locomotor activity, nociception and intravenous remifentanil self-administration. The parents showed a range of remifentanil self-administration, especially in the female rats. The offspring of the parents with low and high remifentanil self-administration showed significant differences in specific behavioral functions. On the hotplate test of nociception, the female offspring parents with high remifentanil self-administration had significantly longer hotplate latencies, indicating reduced nociception, than the female offspring of parents with low remifentanil-self-administration, whereas there was no difference in the male offspring of low and high responding parents. In the elevated plus maze test of anxiety-like behavior, the offspring of the parents with high remifentanil intake showed more anxiety-like behavior than the offspring of the parents with low remifentanil intake regardless of sex. Locomotor activity was not significantly different. Interestingly, no significant differences in remifentanil self-administration in the offspring of parents with low and high remifentanil self-administration were detected. Overall, our data suggest a considerable range in remifentanil self-administration in rats and the offspring of rats with high opioid self-administration exhibit different behaviors vs offspring of rats with low opioid self-administration.Item Open Access Perinatal diazinon exposure compromises the development of acetylcholine and serotonin systems.(Toxicology, 2019-08) Slotkin, Theodore A; Skavicus, Samantha; Ko, Ashley; Levin, Edward D; Seidler, Frederic JOrganophosphate pesticides are developmental neurotoxicants. We gave diazinon via osmotic minipumps implanted into dams prior to conception, with exposure continued into the second postnatal week, at doses (0.5 or 1 mg/kg/day) that did not produce detectable brain cholinesterase inhibition. We evaluated the impact on acetylcholine (ACh) and serotonin (5-hydroxytryptamine, 5HT) systems in brain regions from adolescence through full adulthood. Diazinon produced deficits in presynaptic ACh activity with regional and sex selectivity: cerebrocortical regions and the hippocampus were affected to a greater extent than were the striatum, midbrain or brainstem, and females were more sensitive than males. Diazinon also reduced nicotinic ACh receptors and 5HT1A receptors, with the same regional and sex preferences. These patterns were similar to those of diazinon given in a much more restricted period (postnatal day 1-4) but were of greater magnitude and consistency; this suggests that the brain is vulnerable to diazinon over a wide developmental window. Diazinon's effects differed from those of the related organophosphate, chlorpyrifos, with regard to regional and sex selectivity, and more importantly, to the effects on receptors: chlorpyrifos upregulates nicotinic ACh receptors and 5HT receptors, effects that compensate for the presynaptic ACh deficits. Diazinon can thus be expected to have worse neurodevelopmental outcomes than chlorpyrifos. Further, the disparities between diazinon and chlorpyrifos indicate the problems of predicting the developmental neurotoxicity of organophosphates based on a single compound, and emphasize the inadequacy of cholinesterase inhibition as an index of safety.Item Open Access The Developmental Neurotoxicity of Tobacco Smoke Can Be Mimicked by a Combination of Nicotine and Benzo[a]Pyrene: Effects on Cholinergic and Serotonergic Systems.(Toxicological sciences : an official journal of the Society of Toxicology, 2019-01) Slotkin, Theodore A; Skavicus, Samantha; Ko, Ashley; Levin, Edward D; Seidler, Frederic JTobacco smoke contains polycyclic aromatic hydrocarbons (PAHs) in addition to nicotine. We compared the developmental neurotoxicity of nicotine to that of the PAH archetype, benzo[a]pyrene (BaP), and also evaluated the effects of combined exposure to assess whether PAHs might exacerbate the adverse effects of nicotine. Pregnant rats were treated preconception through the first postnatal week, modeling nicotine concentrations in smokers and a low BaP dose devoid of systemic effects. We conducted evaluations of acetylcholine (ACh) and serotonin (5-hydroxytryptamine, 5HT) systems in brain regions from adolescence through full adulthood. Nicotine or BaP alone impaired indices of ACh presynaptic activity, accompanied by upregulation of nicotinic ACh receptors and 5HT receptors. Combined treatment elicited a greater deficit in ACh presynaptic activity than that seen with either agent alone, and upregulation of nAChRs and 5HT receptors was impaired or absent. The individual effects of nicotine and BaP accounted for only 60% of the combination effects, which thus displayed unique properties. Importantly, the combined nicotine + BaP exposure recapitulated the effects of tobacco smoke, distinct from nicotine. Our results show that the effects of nicotine on development of ACh and 5HT systems are worsened by BaP coexposure, and that combination of the two agents contributes to the greater impact of tobacco smoke on the developing brain. These results have important implications for the relative safety in pregnancy of nicotine-containing products compared with combusted tobacco, both for active maternal smoking and secondhand exposure, and for the effects of such agents in "dirty" environments with high PAH coexposure.