Valsalva manoeuvre effect on distribution of lung damage in heroin inhalation

H4K5 histone acetylation of BRG1 is associated with heroin administration rather than addiction

Diacetylmorphine hydrochloride (heroin) addiction is a chronic relapsing brain disorder that is a heavy public health burden worldwide. Brm/SWI2-related gene-1 (BRG1) is a tumor suppressor gene that can influence embryogenesis and the development of the cerebellum. The current study aimed to investigate the effect of histone H4 lysine 5 (H4K5) modifications on the BRG1 gene in brain tissue of the ventral tegmental area (VTA) of heroin-addicted rats. A total of 21 male Sprague Dawley rats were raised in a standard manner and underwent heroin self-administration training. Rats were randomly divided into three equal groups: Group A, self-administered delivery of heroin; group B, yoked delivery of heroin; and group C, yoked delivery of saline. The VTA was harvested and subjected to chromatin immunoprecipitation (ChIP) analysis. Gene expression was evaluated by quantitative polymerase chain reaction. We calculated the recovery rate, which indicated the percentage of the total input BRG1 recovered by ChIP. Our results showed that BRG1 was less associated with H4K5 histone modification in the group of rats that underwent heroin self-administration than in the other two groups (A vs. B, P=0.031; A vs. C, P=0.067). The recovery fold changes of the self-administration group and the passive-administration group were significantly different from those of the group with yoked saline (A vs. C, P=0.013; B vs. C, P=0.009; A vs. B, P=0.731). The results of the current study demonstrated that H4K5 histone acetylation of BRG1 in the VTA may be associated with heroin administration, but not addiction.

The effects of opioids on the lung

The term opioid refers to a broad class of medications that are used most frequently for their analgesic effects. Along with this effect, they also produce euphoria, and it is for this reason that they have been used illicitly, as well as medicinally, for thousands of years. While the most well-known complications of opioid use and misuse include respiratory and central nervous system depression, there are many other toxicities that have been associated with these drugs. Many complications can occur with multiple different opioids, such as non-cardiogenic pulmonary edema, while many of the complications are unique to the opioid used as well as the route of administration. This review focuses on the pulmonary complications associated with opioid use and abuse, but opioids can affect nearly every organ system. Their effects on the pulmonary system can be direct, such as causing granulomatous change, but they can also work indirectly. For example, opioids cause respiratory depression by decreasing sensitivity of peripheral chemoreceptors to carbon dioxide and decreasing activity in the central respiratory centers. Opioids have also been reported to affect the immune system, and place users at increased risk for many different infectious complications. Patients can have a wide array of signs and symptoms, sometimes making it difficult to recognize opioids as a cause for a patient's clinical picture. Due to the sedative effects of opioids, patients are also often not able to provide a reliable history. Knowledge of the possible toxicities of opioids can help prepare a physician to recognize the many complications associated with opioid use.

The large spectrum of pulmonary complications following illicit drug use: features and mechanisms

Damage to lungs may occur from systemic as well as inhalational exposure to various illegal drugs of abuse. Aspiration pneumonia probably represents the most common pulmonary complication in relation to consciousness impairment. Some pulmonary consequences may be specifically related to one given drug. Prolonged smoking of marijuana may result in respiratory symptoms suggestive of obstructive lung disease. Non-cardiogenic pulmonary edema has been attributed to heroin, despite debated mechanisms including attempted inspiration against a closed glottis, hypoxic damage to alveolar integrity, neurogenic vasoactive response to stress, and opiate-induced anaphylactoid reaction. Naloxone-related precipitated withdrawal resulting in massive sympathetic response with heart stunning has been mistakenly implicated. In crack users, acute respiratory syndromes called "crack-lung" with fever, hemoptysis, dyspnea, and pulmonary infiltration on chest X-rays have been reported up-to 48h after free-base cocaine inhalation, with features of pulmonary edema, interstitial pneumonia, diffuse alveolar hemorrhage, and eosinophil infiltration. The high-temperature of volatilized cocaine and the presence of impurities, as well as cocaine-induced local vasoconstriction have been suggested to explain alveolar damage. Some other drug-related pulmonary insults result from the route of drug self-administration. In intravenous drug users, granulomatous pneumonia with multinodular patterns on thoracic imaging is due to drug contaminants like talcum. Septic embolism from right-sided endocarditis represents an alternative diagnosis in case of sepsis from pulmonary origin. Following inhalation, pneumothorax, and pneumomediastinum have been attributed to increased intrathoracic pressure in relation to vigorous coughing or repeated Valsalva maneuvers, in an attempt to absorb the maximal possible drug amount. In conclusion, pulmonary consequences of illicit drugs are various, resulting in both acute life-threatening conditions and long-term functional respiratory sequelae. A better understanding of their spectrum and the implicated mechanisms of injury should help to improve patient management.