Biology subjects

Chartoff, E. H.

Publications and source records attributed to Chartoff, E. H..

4 recordsLinked to original sources

bioRxiv2024

Sex-specific behavioral and thalamo-accumbal circuit adaptations after oxycodone abstinence.

Opioid use disorder is characterized by compulsive drug seeking and heightened relapse vulnerability following abstinence, a phenomenon known as incubation of craving. Although preclinical data suggest similar behavioral expression of opioid use between sexes, conclusive evidence on sex differences in craving and relapse across abstinence periods remains lacking. Here, we investigated the effects of abstinence from oxycodone self-administration on neurotransmission in the paraventricular thalamus (PVT) to nucleus accumbens shell (NAcSh) pathway in male and female rats. Using optogenetics and ex vivo electrophysiology, we assessed synaptic strength, glutamate release probability, and intrinsic excitability of NAcSh medium spiny neurons (MSNs) following 1 (acute) or 14 (prolonged) days of forced abstinence. No sex differences were observed in oxycodone self-administration or somatic withdrawal. However, females exhibited greater cue-induced relapse after prolonged but not acute abstinence. Prolonged abstinence produced comparable increases in PVT-NAcSh synaptic strength and presynaptic glutamate release probability in both sexes, while inhibitory transmission and MSN excitability were largely unaltered. The dissociation between comparable circuit-level plasticity and sex-specific relapse vulnerability suggests that PVT-NAcSh strengthening represents a shared neuroadaptation to oxycodone abstinence, while mechanisms driving heightened relapse in females likely involve additional circuit elements that remain to be identified.

neuroscience↗

bioRxiv2021

Prenatal opioid exposure inhibits microglial sculpting of the dopamine system during adolescence

The current opioid epidemic has dramatically increased the number of children who are prenatally exposed to opioids, including oxycodone. A number of social and cognitive abnormalities have been documented in these children as they reach young adulthood. However, little is known about the mechanisms underlying developmental effects of prenatal opioid exposure. Microglia, the resident immune cells of the brain, respond to acute opioid exposure in adulthood. Moreover, microglia are known to sculpt neural circuits during healthy development. Indeed, we recently found that microglial phagocytosis of dopamine D1 receptors (D1R) in the nucleus accumbens (NAc) is required for the natural developmental decline in NAc-D1R that occurs between adolescence and adulthood in rats. This microglial pruning occurs only in males, and is required for the normal developmental trajectory of social play behavior. However, virtually nothing is known as to whether this developmental program is altered by prenatal exposure to opioids. Here, we show in rats that maternal oxycodone self-administration during pregnancy leads to reduced adolescent microglial phagocytosis of D1R and subsequently higher D1R density within the NAc in adult male, but not female, offspring. Finally, we show that prenatal opioid exposure abolishes the extinction of oxycodone-conditioned place preference in these male offspring. This work demonstrates for the first time that microglia play a key role in translating prenatal opioid exposure to long-term changes in neural systems and behavior. HighlightsO_LIPrenatal opioid exposure decreases offspring viability and body weight in males and females C_LIO_LIPrenatal opioid exposure decreases microglial phagocytosis of D1R in the nucleus accumbens in males only C_LIO_LIPrenatal opioid exposure increases nucleus accumbens dopamine D1 receptor expression in males but not females C_LIO_LIAdult males fail to extinguish oxycodone-conditioned place preference following prenatal oxycodone exposure C_LI

neuroscience↗

bioRxiv2020

Intracranial self-stimulation and concomitant behaviors following systemic methamphetamine administration in Hnrnph1 mutant mice

RationaleAddiction to methamphetamine (MA) is a major public health issue in the United States. While psychostimulant use disorders are heritable, their genetic basis remains poorly understood. We previously identified heterogeneous nuclear ribonucleoprotein H1 (Hnrnph1; H1) as a quantitative trait gene underlying sensitivity to MA-induced locomotor activity. Mice heterozygous for a frameshift deletion in the first coding exon of H1 (H1+/-) showed reduced MA phenotypes including oral self-administration, locomotor activity, dopamine release, and dose-dependent differences in MA conditioned place preference. However, the effects of H1+/- on innate and MA-modulated reward sensitivity are not known. ObjectivesWe examined innate reward sensitivity and modulation by MA in H1+/- mice via intracranial self-stimulation (ICSS). MethodsWe used intracranial self-stimulation (ICSS) of the medial forebrain bundle to assess shifts in reward sensitivity following acute, ascending doses of MA (0.5-4.0 mg/kg, i.p.) using a within-subjects design. We also assessed video-recorded behaviors during ICSS testing sessions. ResultsH1+/- mice displayed reduced normalized maximum response rates, H1+/- females showed lower normalized M50 values compared to wild-type females following MA, and H1+/- influenced ICSS responding relative to maximum baseline rates. There was a dose-dependent reduction in distance to the response wheel following MA administration, providing an additional measure of reward-related behavior. ConclusionsH1+/- mice displayed reduced reward facilitation following MA in a sex- and dose-dependent manner. This result expands upon the set of MA-induced phenotypes observed in H1+/- mice.

neuroscience↗

bioRxiv2019

Attenuated Dopamine Receptor Signaling in Nucleus Accumbens Core in a Rat Model of Chemically-Induced Neuropathy

Neuropathy is major source of chronic pain that can be caused by mechanically or chemically induced nerve injury. Previous work in a rat model of neuropathic pain demonstrated that bilateral formalin injection into the hind paws produced mechanical hypersensitivity (allodynia) and depressed responding for intracranial self-stimulation (ICSS). To determine whether neuropathy alters dopamine receptor responsiveness in mesolimbic brain regions, we examined dopamine D1-like and D2-like receptor (D1/2R) signaling and expression in male rats 14 days after bilateral intraplantar formalin injections into both rear paws. D2R-mediated G-protein activation and expression of the D2R long, but not short, isoform were reduced in nucleus accumbens (NAc) core, but not in NAc shell, caudate-putamen (CPu) or ventral tegmental area (VTA) of formalin-compared to saline-treated rats. In addition, D1R-stimulated adenylyl cyclase (AC) activity was also reduced in NAc core, but not in NAc shell or prefrontal cortex, of formalin-treated rats, whereas D1R expression was unaffected. Expression of other proteins involved in dopamine neurotransmission, including dopamine uptake transporter (DAT) and tyrosine hydroxylase (TH), were unaffected by formalin treatment. In behavioral tests, the effects of D2R agonists on ICSS were attenuated in formalin-treated rats, whereas the effects of D1R agonists were unchanged. These results indicate that intraplantar formalin as a model of chemically induced neuropathy produces attenuation of highly specific DA receptor signaling processes in NAc core of male rats.

pharmacology and toxicology↗