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Parkinson Disease (PD) is increasingly considered a proteinopathy and lipidopathy. This proteinopathy+lipidopathy paradigm has been further refined to a fatty acid (FA)‐opathy, centering dysregulated FA metabolism as fundamental in PD lipid dysfunction. FA dysfunction can disrupt alpha‐synuclein (αS)‐membrane interactions, altering αS localization, conformation, and aggregation. Correcting FA dyshomeostasis rescues PD‐associated αS phenotypes and is a promising strategy for disease‐modifying therapeutics. Herein, we consider the impact of PD FA dyshomeostasis in modifying the bioactive oxylipin‐ome. Oxylipin metabolism is complex, and the role of oxylipins in PD is not yet fully determined. This perspective considers PD‐associated differences oxylipin profiles, oxylipin precursor polyunsaturated fatty acids (PUFAs), and oxylipin biosynthetic enzymes in human PD studies to explore a potential PD oxylipin‐ome signature. Founded on disrupted oxylipin and oxylipin precursor PUFA abundance, higher PUFA intake reducing PD risk and progression, and the association between cyclooxygenase (COX) inhibition and lower PD incidence, we posit that the oxylipin‐ome plays a role in PD. Oxylipin metabolism may be a novel target for PD biomarkers and disease‐modifying therapeutics.

Sensitivity to different pain modalities has a genetic basis that remains largely unknown. Employing closely related inbred mouse substrains can facilitate gene mapping of nociceptive behaviors in preclinical pain models. We previously reported enhanced sensitivity to acute thermal nociception in C57BL/6J (B6J) versus C57BL/6N (B6N) substrains. Here, we expanded on nociceptive phenotypes and observed an increase in formalin-induced inflammatory nociceptive behaviors and paw diameter in B6J versus B6N mice (Charles River Laboratories). No strain differences were observed in mechanical or thermal hypersensitivity or in edema following the Complete Freund’s Adjuvant model of inflammatory pain, indicating specificity in the inflammatory nociceptive stimulus. In the chronic constrictive nerve injury, a model of neuropathic pain, no strain differences were observed in baseline mechanical threshold or in mechanical hypersensitivity up to one month post-chronic constrictive nerve injury. We replicated the enhanced thermal nociception in the 52.5°C hot plate test in B6J versus B6N mice from The Jackson Laboratory. Using a B6J × B6N-F2 cross (N = 164), we mapped a major quantitative trait locus underlying hot plate sensitivity to chromosome 7 that peaked at 26 Mb (log of the odds [LOD] = 3.81, p < 0.01; 8.74 Mb-36.50 Mb) that was more pronounced in males. Genes containing expression quantitative trait loci associated with the peak nociceptive marker that are implicated in pain and inflammation include Ryr1, Cyp2a5, Pou2f2, Clip3, Sirt2, Actn4, and Ltbp4 (false discovery rate < 0.05). Future studies involving positional cloning and gene editing will determine the quantitative trait gene(s) and potential pleiotropy of this locus across pain modalities.

Binge eating (BE) is a heritable trait associated with eating disorders and involves episodes of rapid, large amounts of food consumption. We previously identified cytoplasmic FMR1-interacting protein 2 (Cyfip2) as a genetic factor underlying compulsive-like BE in mice. CYFIP2 is a homolog of CYFIP1 which is one of four paternally-deleted genes in patients with Type I Prader-Willi Syndrome (PWS), a neurodevelopmental disorder whereby 70% of cases involve paternal 15q11-q13 deletion. PWS symptoms include hyperphagia, obesity (if untreated), cognitive deficits, and obsessive-compulsive behaviors. We tested whether Cyfip1 haploinsufficiency (+/−) would enhance compulsive-like behavior and palatable food (PF) intake in a parental origin- and sex-dependent manner on two Cyfip2 genetic backgrounds, including the BE-prone C57BL/6N (Cyfip2N/N) background and the BE-resistant C57BL/6J (Cyfip2J/J) background. Cyfip1+/− mice showed increased compulsive-like behavior on both backgrounds and increased PF intake on the Cyfip2N/N background. In contrast, maternal Cyfip1 haploinsufficiency on the BE-resistant Cyfip2J/J background induced a robust escalation in PF intake in wild-type Cyfip1J/J males while having no effect in Cyfip1J/- males. Notably, induction of behavioral phenotypes in wild-type males following maternal Fmr1+/− has previously been reported. In the hypothalamus, there was a paternally-enhanced reduction in CYFIP1 protein whereas in the nucleus accumbens, there was a maternally-enhanced reduction in CYFIP1 protein. Nochange in FMR1 protein (FMRP) was observed in Cyfip1+/− mice, regardless of parental origin. To summarize, Cyfip1 haploinsufficiency increased compulsive-like behavior and induced genetic background-dependent, sex-dependent, and parent-of-origin-dependent effects on PF consumption and CYFIP1 expression that could have relevance for neurodevelopmental and neuropsychiatric disorders.

Opioid use disorder is heritable, yet its genetic etiology is largely unknown. C57BL/6J and C57BL/6NJ mouse substrains exhibit phenotypic diversity in the context of limited genetic diversity which together can facilitate genetic discovery. Here, we found C57BL/6NJ mice were less sensitive to oxycodone (OXY)‐induced locomotor activation versus C57BL/6J mice in a conditioned place preference paradigm. Narrow‐sense heritability of OXY‐induced locomotor activity traits ranged from 0.22 to 0.31, implicating suitability for genetic analysis. Quantitative trait locus (QTL) mapping in an F2 cross identified a chromosome 1 QTL explaining 7%–12% of the variance in OXY locomotion and anxiety‐like withdrawal in the elevated plus maze. A second QTL for EPM withdrawal behavior on chromosome 5 near Gabra2 (alpha‐2 subunit of GABA‐A receptor) explained 9% of the variance. To narrow the chromosome 1 locus, we generated recombinant lines spanning 163–181 Mb, captured the QTL for OXY locomotor traits and withdrawal, and fine‐mapped a 2.45‐Mb region (170.16–172.61 Mb). Transcriptome analysis identified five, localized striatal cis‐eQTL transcripts and two were confirmed at the protein level (KCNJ9, ATP1A2). Kcnj9 codes for a potassium channel (GIRK3) that is a major effector of mu opioid receptor signaling. Atp1a2 codes for a subunit of a Na+/K+ ATPase enzyme that regulates neuronal excitability and shows functional adaptations following chronic opioid administration. To summarize, we identified two candidate genes underlying the physiological and behavioral properties of opioids, with direct preclinical relevance to investigators employing these widely used substrains and clinical relevance to human genetic studies of opioid use disorder. We exploited near‐isogenic C57BL/6 substrains to fine‐map a 2.45‐Mb region containing DNA variants underlying oxycodone behaviors. We mapped a genomic region on distal chromosome 1 and identified genotype‐driven, differentially expressed mRNAs and proteins within this region and DNA variants. Atp1a2 and Kcnj9 as two likely candidate genes underlying oxycodone behavior.

Methamphetamine addiction remains a major public health concern in the United States that has paralleled the opioid epidemic. Psychostimulant use disorders have a heritable genetic component that remains unexplained. Methamphetamine targets membrane and vesicular transporters to increase synaptic dopamine, norepinephrine, and serotonin. We previously identified (heterogeneous nuclear ribonucleoprotein H1) as a quantitative trait gene underlying methamphetamine behavioral sensitivity. encodes the RNA-binding protein hnRNP H1 that is ubiquitously expressed in neurons throughout the brain. Gene-edited mice with a heterozygous frameshift deletion in first coding exon of showed reduced methamphetamine-induced dopamine release and behaviors. To inform the mechanism linking hnRNP H with methamphetamine neurobehavioral effects, we surveyed the mRNA targetome of hnRNP H via cross-linking immunoprecipitation coupled with RNA-sequencing in striatal tissue at baseline and at 30 min post-methamphetamine in wild-type male and female C57BL/6J mice. Methamphetamine induced changes in RNA-binding targets of hnRNP H in mice, including differential binding to 3'UTR targets and multiple enriched mRNAs involved in synaptic plasticity. Targetome, transcriptome, and spliceome analyses triangulated on as a suggestive target, with differences in hnRNP H binding, gene expression and splicing following methamphetamine treatment (2 mg/kg, i.p.). Furthermore, pre-treatment with pregabalin, an inhibitor of α2δ2 and α2δ1 voltage-gated calcium channel subunits, attenuated methamphetamine-induced locomotor activity in male and female mice, supporting a role for Cacna2d1/d2 in methamphetamine locomotor stimulant sensitivity. Our study identifies a dynamic hnRNP H RNA targetome that can rapidly and adaptively respond to methamphetamine to regulate gene expression and likely synaptic plasticity and behavior.

Opioid use disorder is heritable, yet its genetic etiology is largely unknown. C57BL/6J and C57BL/6NJ mouse substrains exhibit phenotypic diversity in the context of limited genetic diversity which together can facilitate genetic discovery. Here, we found C57BL/6NJ mice were less sensitive to oxycodone (OXY)-induced locomotor activation versus C57BL/6J mice in a conditioned place preference paradigm. Narrow-sense heritability was estimated at 0.22-0.31, implicating suitability for genetic analysis. Quantitative trait locus (QTL) mapping in an F2 cross identified a chromosome 1 QTL explaining 7-12% of the variance in OXY locomotion and anxiety-like withdrawal in the elevated plus maze. A second QTL for EPM withdrawal behavior on chromosome 5 near (alpha-2 subunit of GABA-A receptor) explained 9% of the variance. To narrow the chromosome 1 locus, we generated recombinant lines spanning 163-181 Mb, captured the QTL for OXY locomotor traits and withdrawal, and fine-mapped a 2.45-Mb region (170.16-172.61 Mb). Transcriptome analysis identified five, localized striatal cis-eQTL transcripts and two were confirmed at the protein level (KCNJ9, ATP1A2). codes for a potassium channel (GIRK3) that is a major effector of mu opioid receptor signaling. codes for a subunit of a Na+/K+ ATPase enzyme that regulates neuronal excitability and shows functional adaptations following chronic opioid administration. To summarize, we identified two candidate genes underlying the physiological and behavioral properties of opioids, with direct preclinical relevance to investigators employing these widely used substrains and clinical relevance to human genetic studies of opioid use disorder.

The opioid epidemic led to an increase in the number of Neonatal Opioid Withdrawal Syndrome (NOWS) cases in infants born to opioid-dependent mothers. Hallmark features of NOWS include weight loss, severe irritability, respiratory problems, and sleep fragmentation. Mouse models provide an opportunity to identify brain mechanisms that contribute to NOWS. Neonatal outbred Swiss Webster Cartworth Farms White (CFW) mice were administered morphine (15mg/kg, s.c.) twice daily for postnatal days (P) 1-14, an approximate of the third trimester of human gestation. Male and female mice underwent behavioral testing on P7 and P14 to determine the impact of opioid exposure on anxiety and pain sensitivity. Ultrasonic vocalizations (USVs) and daily body weights were also recorded. Brainstems containing pons and medulla were collected during morphine withdrawal on P14 for RNA-sequencing. Morphine induced weight loss from P2-14, which persisted during adolescence (P21) and adulthood (P50). USVs markedly increased at P7 in females, emerging earlier than males. On P7 and P14, both morphine exposed female and male mice displayed hyperalgesia on the hot plate and tail flick assays, with females having greater hyperalgesia than males. Morphine-exposed mice exhibited increased anxiety-like behavior in the open-field arena at P21. Transcriptome analysis of the brainstem (medulla plus pons), an area implicated in opioid withdrawal and NOWS, identified pathways enriched for noradrenergic signaling in females and males. We also found sex-specific pathways related to mitochondrial function and neurodevelopment in females and circadian entrainment in males. Sex-specific transcriptomic neuroadaptations implicate unique neurobiological mechanisms underlying NOWS-like behaviors. Competing Interest Statement The authors have declared no competing interest.

Objective: Binge eating is a heritable quantitative trait associated with eating disorders (ED) and refers to the rapid consumption of a large quantity of energy-dense food that is associated with loss of control, anxiety, and depression. Binge Eating Disorder is the most common ED in adults in the US; however, the genetic basis is unknown. We previously identified robust mouse inbred strain differences between C57BL/6J and DBA/2J in binge-like eating (BLE) of sweetened palatable food (PF) in an intermittent access, conditioned place preference paradigm. Methods: To map the genetic basis of BLE, we phenotyped and genotyped 128 C57BL/6J x DBA/2J-F2 mice. Results: We identified a quantitative trait locus (QTL) on chromosome 13 influencing progressive changes in body weight across training days (LOD = 5.5; 26-39 cM). We also identified two sex-combined QTLs influencing PF intake on chromosome 5 (LOD = 5.6; 1.5-LOD interval = 21-28 cM) and 6 (LOD = 5.3; 1.5-LOD interval = 50-59 cM). Furthermore, sex-specific analyses revealed that the chromosome 6 locus was driven by males (1.5-LOD interval: 52-59 cM) and identified a female-selective QTL for BLE on chromosome 18 (LOD = 4.1; 1.5-LOD interval: 23-35 cM). Systems genetic analysis of the chromosome 6 locus for BLE using GeneNetwork legacy trait datasets from BXD recombinant inbred strains identified Adipor2 and Plxnd1 as two positional, functional, biological candidate genes. Discussion: We identified genetic loci influencing BLE. Future studies will phenotype BXD recombinant inbred strains to fine map loci and support candidate gene nomination and validation. Competing Interest Statement The authors have declared no competing interest.

Binge eating (BE) is a heritable symptom of eating disorders associated with anxiety, depression, malnutrition, and obesity. Genetic analysis of BE could facilitate therapeutic discovery. We used an intermittent, limited access BE paradigm involving sweetened palatable food (PF) to examine genetic differences in BE, conditioned food reward, and compulsive-like eating between C57BL/6J (B6J) and DBA/2J (D2J) inbred mouse strains. D2J mice showed a robust escalation in intake and conditioned place preference for the PF-paired side. D2J mice also showed a unique style of compulsive-like eating in the light/dark conflict test where they rapidly hoarded and consumed PF in the preferred unlit environment. BE and compulsive-like eating exhibited narrow-sense heritability estimates between 56 and 73 percent. To gain insight into the genetic basis, we phenotyped and genotyped a small cohort of 133 B6J x D2J-F2 mice at the peak location of three quantitative trait loci (QTL) previously identified in F2 mice for sweet taste (chromosome 4: 156 Mb), bitter taste (chromosome 6: 133 Mb) and behavioral sensitivity to drugs of abuse (chromosome 11: 50 Mb). The D2J allele on chromosome 6 was associated with greater PF intake on training days and greater compulsive-like PF intake, but only in males, suggesting that decreased bitter taste may increase BE in males. The D2J allele on chromosome 11 was associated with an increase in final PF intake and slope of escalation across days. Future studies employing larger crosses and genetic reference panels comprising B6J and D2J alleles will identify causal genes and neurobiological mechanisms. Footnotes * This manuscript now includes additional studies targeting three previously identified QTLs that could contribute to the genetic differences in binge eating. These QTLs included two for taste perception (chromosomes 4 and 6) and one for behavioral sensitivity to drugs of abuse (chromosome 11). Additionally, we now report sex differences as they relate to binge eating and compulsive-like eating, as well as their relationship with taste perception.

Binge eating (BE) is a heritable symptom of eating disorders with an unknown genetic etiology. Rodent models for BE of palatable food permit the study of genetic and biological mechanisms. We previously used genetic mapping and transcriptome analysis to map a coding mutation in Cyfip2 associated with increased BE in the BE-prone C57BL/6NJ substrain compared to the BE-resistant C57BL/6J substrain. The increase in BE in C57BL/6NJ mice was associated with a decrease in transcription of genes enriched for myelination in the striatum. Here, we tested the hypothesis that decreasing myelin levels with the demyelinating agent cuprizone would enhance BE. Mice were treated with a 0.3% cuprizone home cage diet for two weeks. Following a three-week recovery period, mice were trained for BE in an intermittent, limited access procedure. Cuprizone induced similar weight loss in both substrains and sexes that recovered within 48 h after removal of the cuprizone diet. Surprisingly, cuprizone reduced BE in male but not female C57BL/6NJ mice while having no effect in C57BL/6J mice. Cuprizone also reduced myelin basic protein (MBP) at seven weeks post-cuprizone removal while having no effect on myelin-associated glycoprotein (MAG) at this time point. C57BL/6N mice also showed less MBP than C57BL/6J mice. There were no statistical interactions of Treatment with Sex on MBP levels, indicating that differences in MBP are unlikely to account for sex differences in BE. To summarize, cuprizone induced an unexpected, male-specific reduction in BE which could indicate sex-specific biological mechanisms that depend on genetic background.