Identity construction among second-generation Chinese in Italy: a perspective on the symbolic function of language.

Prescription opioids continue to be a major public health issue across the US, as evidenced by a total of over 108,000 reported overdose deaths in 2022, with 76 percent of those deaths attributed to opioid overdoses (). Oxycodone, one of the several prescription opioids, is also highly linked to both opioid use disorders and overdose deaths. Additionally, there is a high societal cost from the misuse of prescription opioids, with estimated annual expenditures for health care, law enforcement, and loss of productivity reaching $78.5 billion in 2013 (). Individuals misusing prescription opioids are also significantly more likely to begin using heroin than non-misusers of prescription opioids, indicating a strong link between the two opioids (; ). Oxycodone is a semi-synthetic opioid analgesic and acts primarily as a mu opioid receptor (MOP) agonist (). Indeed, oxycodone possesses rewarding and reinforcing actions in rodents (; ; ; ; ; ). Furthermore, C57BL/6J mice () as well as non-human primates () discriminate between oxycodone and vehicle. In recreational opioid users, intravenous oxycodone has been associated with liking and high (), suggesting that, like other opioid agonists, it has a high potential for abuse. While oxycodone is a major player in today’s opioid epidemic, research examining the rewarding effects of oxycodone in animal models is limited compared to that of other opioids, such as morphine. Research into the rewarding effects of opioids in animal models often utilizes experimenter-administered drug delivery methods, i.e., subcutaneous or intraperitoneal administration. However, epidemiologic studies indicate that prescription opioid misuse occurs most frequently through oral ingestion of oxycodone, and that some individuals will continue to ingest prescription opioids orally even after they have access to abuse-deterrent formulations (). Therefore, it is important to develop preclinical models of opioid reward that utilize voluntary oral self-administration of the test drug to increase the translational relevance of the results. The place conditioning paradigm, a Pavlovian conditioning paradigm, is widely used to evaluate the motivational and rewarding effects of abused drugs. In this paradigm, subjects learn to associate the interoceptive effects of a drug with a unique environmental context and thus express a preference for the drug-paired environment, i.e., they exhibit a conditioned place preference (CPP) response when tested under a drug-free state (; ; ). The place conditioning paradigm is a valuable approach to study the acquisition of CPP, its extinction, and reinstatement after re-exposure to the drug, including oxycodone (; ; ; ; ). The use of CPP provides an opportunity to evaluate the rewarding effects of opioids and the likelihood of relapses in response to re-exposure to the drug, because CPP involves associative learning and memory processes. Therefore, this study was designed to develop a preclinical model of reward employing voluntary oral oxycodone self-administration in mice to assess whether oral oxycodone self-administration would be associated with reward-related behavior. We examined the acquisition, extinction, and reinstatement of oxycodone-induced CPP in male and female C57BL/6J mice as well as in male mice lacking MOP and their wild-type littermates.