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Higher anhedonia during withdrawal from initial opioid exposure is protective against subsequent opioid self-administration in rats.

ABSTRACT: RATIONALE:Understanding factors contributing to individual differences in vulnerability to opioid addiction is essential for developing more effective preventions and treatments, yet few reliable behavioral predictors of subsequent opioid self-administration have been identified in rodents. Sensitivity to the acute effects of initial drug exposure predicts later addiction vulnerability in both humans and animals, but the relationship between sensitivity to withdrawal from initial drug exposure and later drug use vulnerability is unclear. OBJECTIVE:The goal of the current study was to evaluate whether the degree of anhedonia experienced during withdrawal from early opioid exposure predicts subsequent vulnerability to opioid self-administration. METHODS:Rats were first tested for withdrawal sensitivity following acute injections of morphine (i.e., "acute dependence"), measured as elevations in intracranial self-stimulation (ICSS) thresholds (anhedonia-like behavior) during naloxone-precipitated and spontaneous withdrawal. Rats were then tested for addiction-like behavior using various measures of i.v. morphine self-administration (MSA) including acquisition, demand, extinction, and reinstatement induced by morphine, stress, and/or drug-associated cues. RESULTS:Greater naloxone-precipitated withdrawal across repeated morphine injections and greater peak spontaneous withdrawal severity following a single morphine injection were associated with lower addiction-like behavior on multiple MSA measures. Withdrawal-induced anhedonia predicted a wider range of MSA measures than did any individual measure of MSA itself. CONCLUSIONS:Our data establish WIA as one of the first behavioral measures to predict individual differences in opioid SA in rodents. This model promises to be useful for furthering our understanding of behavioral and neurobiological mechanisms underlying vulnerability to opioid addiction.

SUBMITTER: Swain Y

PROVIDER: S-EPMC7354901 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:ObjectiveTo evaluate the severity of neonatal opioid withdrawal syndrome (NOWS) in infants prenatally exposed to medications for opioid use disorder (MOUD) and serotonin reuptake inhibitors (SRI).MethodsA prospective cohort included 148 maternal-infant pairs categorized into MOUD (n = 127) and MOUD + SRI (n = 27) groups. NOWS severity was operationalized as the infant's need for pharmacologic treatment with opioids, duration of hospitalization, and duration of treatment. The association between prenatal SRI exposure and the need for pharmacologic treatment (logistic regression), time-to-discharge, and time-to-treatment discontinuation (Cox proportional hazards modeling) was examined after adjusting for the type of maternal MOUD, use of hydroxyzine, other opioids, benzodiazepines/sedatives, alcohol, tobacco, marijuana, gestational age, and breastfeeding.ResultsInfants in the MOUD + SRI group were more likely to receive pharmacologic treatment for NOWS (OR = 3.58; 95% CI: 1.31; 9.76) and had a longer hospitalization (median: 11 vs. 6 days; HR = 0.54; 95% CI: 0.33; 0.89) compared to the MOUD group. With respect to time-to-treatment discontinuation, no association was observed in infants who received treatment (HR = 0.59; 95% CI: 0.26, 1.32); however, significant differences were observed in the entire sample (HR = 0.55; 95% CI: 0.34, 0.89).ConclusionsUse of SRIs among pregnant women on MOUD might be associated with more severe NOWS.ImpactA potential drug-drug interaction between maternal SRIs and opioid medications that inhibit the reuptake of serotonin has been hypothesized but not carefully evaluated in clinical studies. Results of this prospective cohort indicate that the use of SRIs among pregnant women on MOUD is associated with more severe neonatal opioid withdrawal syndrome. This is the first prospective study which carefully examined effect modification between the type of maternal MOUD and SRI use on neonatal outcomes. This report lays the foundation for treatment optimization in pregnant women with co-occurring mental health and substance use disorders.

Project description:Although opioids are potent analgesics, a consequence of chronic opioid use is hyperalgesia during withdrawal, which may contribute to opioid misuse. Dynorphin, the endogenous ligand of κ-opioid receptors (KORs), is upregulated in opioid-dependent rats and in animal models of chronic pain. However, the role of KORs in opioid withdrawal-induced hyperalgesia remains to be determined. We hypothesized that KOR antagonism would reverse opioid withdrawal-induced hyperalgesia in opioid-dependent rats. Male and female Wistar rats received daily injections of heroin (2-6 mg/kg, SC) and were tested for mechanical sensitivity in the electronic von Frey test 4-6 h into withdrawal. Female rats required significantly more heroin than male rats to reach comparable levels of both heroin-induced analgesia and hyperalgesia (6 mg/kg vs. 2 mg/kg). Once hyperalgesia was established, we tested the effects of the KOR antagonists nor-binaltorphimine (norBNI; 30 mg/kg, SC) and 5'-guanidinonaltrindole (5'GNTI; 30 mg/kg, SC). When the animals continued to receive their daily heroin treatment (or saline treatment in the repeated saline group) five times per week throughout the experiment, both KOR antagonists reversed heroin withdrawal-induced hyperalgesia. The anti-hyperalgesia effect of norBNI was more prolonged in males than in females (14 days vs. 7 days), whereas 5'GNTI had more prolonged effects in females than in males (14 days vs. 4 days). The behavioral effects of 5'GNTI coincided with higher 5'GNTI levels in the brain than in plasma when measured at 24 h, whereas 5'GNTI did not reverse hyperalgesia at 30 min posttreatment when 5'GNTI levels were higher in plasma than in the brain. Finally, we tested the effects of 5'GNTI on naloxone-induced and spontaneous signs of opioid withdrawal and found no effect in either male or female rats. These findings indicate a functional role for KORs in heroin withdrawal-induced hyperalgesia that is observed in rats of both sexes.

Project description:Evidence has emerged demonstrating that ethanol (EtOH) influences cytokine expression within the central nervous system, although most studies have examined long-term exposure. Thus, the cytokine response to an acute EtOH challenge was investigated, in order to characterize profiles of cytokine changes following acute exposure.Rats pups were injected intraperitoneally (i.p.) with 2-g/kg EtOH, and IL-1 mRNA and protein were assessed 0, 60, 120, 180, and 240 minutes post injection (Experiment 1). In Experiments 2 to 5, the expression of several cytokines was examined in adult male rats during acute intoxication (3 hours after 4-g/kg EtOH), as well as withdrawal (18 hours post injection), after i.p. or intragastric (i.g.) EtOH administration.Early in ontogeny, acute EtOH significantly decreased brain IL-1 mRNA and protein. Subsequently, when adult rats were examined, significant and temporally dynamic alterations in central and peripheral cytokines were observed following acute i.p. EtOH exposure (4 g/kg). Although cytokine- and region-dependent central IL-6 expression was generally increased and tumor necrosis factor alpha decreased during intoxication, IL-1 expression exhibited increases during withdrawal. In the periphery, acute i.p. EtOH elevated expression of all cytokines, with the response growing in magnitude as the time post injection increased. Following acute i.g. EtOH (4 g/kg), intoxication-related increases in IL-6 expression were again observed in the paraventricular nucleus of the hypothalamus (PVN), although to a lesser extent. Long-term, voluntary, intermittent EtOH consumption resulted in tolerance to the effects of an i.g. EtOH challenge (4 g/kg) on PVN IL-6 expression, whereas these same elevations in IL-6 expression were still seen in the amygdala in rats with a history of moderate EtOH intake. Treatment with minocycline did not significantly attenuate i.p. or i.g. EtOH-induced changes in central cytokine expression.Together, these studies provide a foundation for understanding fluctuations in central and peripheral cytokines following acute EtOH as potential contributors to the constellation of neural and behavioral alterations observed during EtOH intoxication and withdrawal.

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Higher anhedonia during withdrawal from initial opioid exposure is protective against subsequent opioid self-administration in rats.

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