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Bravo, I. M.

Publications and source records attributed to Bravo, I. M..

4 recordsLinked to original sources

Probing different paradigms of morphine withdrawal on sleep behavior in male and female C57BL/6J mice

Opioid misuse has dramatically increased over the last few decades resulting in many people suffering from opioid use disorder (OUD). The prevalence of opioid overdose has been driven by the development of new synthetic opioids, increased availability of prescription opioids, and more recently, the COVID-19 pandemic. Coinciding with increases in exposure to opioids, the United States has also observed increases in multiple Narcan (naloxone) administrations as life-saving measures for respiratory depression, and, thus, consequently, naloxone-precipitated withdrawal. Sleep dysregulation is a main symptom of OUD and opioid withdrawal syndrome, and therefore, should be a key facet of animal models of OUD. Here we examine the effect of precipitated and spontaneous morphine withdrawal on sleep behaviors in C57BL/6J mice. We find that morphine administration and withdrawal dysregulate sleep, but not equally across morphine exposure paradigms. Furthermore, many environmental triggers promote relapse to drug-seeking/taking behavior, and the stress of disrupted sleep may fall into that category. We find that sleep deprivation dysregulates sleep in mice that had previous opioid withdrawal experience. Our data suggest that the 3-day precipitated withdrawal paradigm has the most profound effects on opioid-induced sleep dysregulation and further validates the construct of this model for opioid dependence and OUD. HighlightsO_LIMorphine withdrawal differentially dysregulates the sleep of male and female mice C_LIO_LI3-day precipitated withdrawal results in larger changes than spontaneous withdrawal C_LIO_LIOpioid withdrawal affects responses to future sleep deprivation differently between sexes C_LI

neuroscience↗

Examining opioid withdrawal scoring and adaptation of global scoring systems to male and female C57BL/6J mice

Opioid Use Disorder (OUD) is a chronic and relapsing psychiatric condition which is currently the leading cause of accidental death in the US. Symptoms of acute opioid withdrawal resemble a flu-like illness which is accompanied by a dysphoric state. Psychological comorbidities such as anxiety, depression, and disordered sleep can persist for months or years, well into the abstinence period. These symptoms are thought to drive further opioid intake in order to alleviate this unpleasant internal state. Many differences in OUD have been documented between male and female patients, with females at higher risk for relapse and overdose. This study sets out to characterize sex differences in symptoms and behavioral adaptations in mice during early withdrawal. Using our moderate dose, three-day precipitated withdrawal paradigm, we discovered significant effects of sex, time, and drug treatment on early withdrawal behaviors, locomotor activity, and gut motility in C57BL/6J mice. Here I will discuss previous methods of condensing behavioral phenotypes into one global withdrawal score, and propose a new methodology. This method increases the ability to detect nuanced effects and allows for more accurate translation across strain, sex, paradigm, and experimental context. Classification of opioid withdrawal-induced behavioral adaptations will allow for improved behavioral analysis of pharmacological manipulations, and investigations of brain circuitry involved in opioid withdrawal, as well as future screening of compounds with potential therapeutic benefit for the treatment of OUD.

neuroscience↗

Divergent behavioral responses in protracted opioid withdrawal in male and female C57BL/6J mice

Persons suffering from opioid use disorder (OUD) experience long-lasting dysphoric symptoms well into extended periods of withdrawal. This protracted withdrawal syndrome is notably characterized by heightened anxiety. Here we investigate if an exacerbated withdrawal model of acute morphine dependence results in lasting behavioral adaptation 6 weeks into forced abstinence. We found that our exacerbated morphine withdrawal paradigm produced distinct impairments in elevated-plus maze, open field, and social interaction tests in male and female mice. These findings will be relevant for future investigation examining the neural mechanisms underlying these behaviors, and will aid in uncovering physiological sex differences in response to opioid withdrawal.

neuroscience↗

Stress-induced alterations of norepinephrine release in the bed nucleus of the stria terminalis of mice

Stress can drive adaptive changes to maintain survival during threatening stimuli. Chronic stress exposure, however, may result in pathological adaptations. A key neurotransmitter involved in stress signaling is norepinephrine. Previous studies show that stress elevates norepinephrine levels in the bed nucleus of the stria terminalis (BNST), a critical node regulating anxiety and upstream of stress responses. Here, we use mice expressing channelrhodopsin in norepinephrine neurons to selectively activate terminals in the BNST, and measure norepinephrine release with fast-scan cyclic voltammetry. Mice exposed to a single restraint session show an identical norepinephrine release profile compared to that of unexposed mice. Mice experiencing five days of restraint stress, however, show elevated noradrenergic release across multiple stimulation parameters, and reduced sensitivity to the 2-adrenergic receptor antagonist idazoxan. These data are the first to examine norepinephrine release in the BNST to tonic and phasic stimulation frequencies, and confirm that repeated stress alters autoreceptor sensitivity.\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC=\"FIGDIR/small/335653_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (28K):\norg.highwire.dtl.DTLVardef@75ef4aorg.highwire.dtl.DTLVardef@b0fd27org.highwire.dtl.DTLVardef@1bc3afborg.highwire.dtl.DTLVardef@c469f1_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗