bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mephedrone: a Synthetic Cathinone with Marked Serotonergic Discriminative Stimulus Effects in Rats
Authors: Erwin Laura Lynn , Jursic Bronco , Winsauer Peter 
Published: November 2023

Mephedrone (4‐methylmethcathinone) was one of the major constituents of the recreational substances referred to as “bath salts”. It is a synthetic cathinone and psychostimulant that can produce auditory and visual hallucinations, as well as problematic cardiovascular effects. This study compared the discriminative stimulus effects of mephedrone (0.32–10 mg/kg) with other prototypical drugs with central nervous system effects, such as ketamine (1.8–18 mg/kg), methylphenidate (1.0–10 mg/kg), and 3,4‐methylenedioxyamphetamine (MDA) (0.32–5.6 mg/kg). Additionally, a selective serotonin reuptake inhibitor, fluoxetine, was administered alone and in combination with mephedrone in order to assess the involvement of the serotonin transporter (SERT). Rats (n=11) were trained to discriminate an intraperitoneal injection of mephedrone from saline under a fixed‐ratio 20 schedule of food presentation. Following training, increasing cumulative doses of mephedrone (0.32–10 mg/kg) produced dose‐dependent increases in mephedrone‐lever responding, with full substitution considered to be greater than 80% drug‐lever responding and partial substitution greater than 50% drug‐lever responding. During substitution tests, MDA and methylphenidate produced 77% and 56% drug‐lever responding, respectively, without significantly decreasing rate of responding (i.e., a 20% decrease from control). Ketamine never produced more than 17% drug‐lever responding at any dose tested. When cumulative doses of fluoxetine (1.8–18 mg/kg) were administered alone, there was little to no substitution. However, when given as a pretreatment, 3.2 mg/kg fluoxetine in combination with mephedrone produced a small (less than two‐fold) shift to the right in the dose‐effect curve for mephedrone‐lever responding. As the pretreatment dose of fluoxetine increased to 5.6 and 10 mg/kg, the ascending portion of the dose‐effect curve for drug‐lever responding shifted to the left and upward. In addition, the 5.6 and 10 mg/kg doses of fluoxetine both partially substituted when administered alone as a bolus injection prior to mephedrone, something which was not seen when administered in cumulative doses. Taken together, these data indicate that the discriminative stimulus effects of mephedrone partially overlap with stimulants such as methylphenidate and MDA, and are also mediated by SERT due to the capacity of fluoxetine to dose‐dependently shift the ascending portion of the curve for mephedrone's discriminative stimulus effects. These data also suggest that doses in the range of 3.2–10 mg/kg likely involve other neurotransmitters such as dopamine.Support or Funding InformationBoard of Regents Fellowship
Effects of Alpha‐2 Norepinephrine Receptor Agonists on Cocaine Self‐Administration in Nonhuman Primate Models
Authors: Czoty Paul W , Coller Michael , Odom Jill , Epperly Phillip , John William S , Nader Susan H , Nader Michael A 
Published: November 2023

Preclinical research has shown that drugs acting at alpha‐2 norepinephrine receptors can decrease stress‐induced reinstatement of cocaine self‐administration in rodents and stress‐induced cocaine craving in humans. Because stress can drive cocaine use, alpha‐2 receptor agonists such as lofexidine (LFX) may have utility in treating cocaine use disorder. In the only published study in nonhuman primates, acute LFX decreased cocaine self‐administration under a fixed‐ratio (FR) schedule, but chronic LFX treatment increased the reinforcing potency of cocaine (Kohut et al., Drug Alcohol Depend, 2013). To expand the range of conditions under which LFX has been studied, we examined effects of acute administration of LFX (0.03–3.0 mg/kg, i.v.) under several procedures in monkeys. More specifically, we examined LFX under conditions used to assess the reinforcing strength of cocaine using concurrent (choice) and progressive‐ratio (PR) schedules of reinforcement. Group‐housed male (n=8) and female (n=4) cynomolgus monkeys self‐administered cocaine under a food‐drug choice procedure. Under this paradigm, ascending cocaine doses (0.0, 0.003, 0.01, 0.03, 0.1 mg/kg per i.v. injection) were available as the alternative to a food pellet under a concurrent fixed‐ratio schedule in successive components of each daily session. Thus, a complete cocaine dose‐effect curve was determined each day. Under these conditions, LFX decreased choice of at least one cocaine dose in 5 of 8 male monkeys and 2 of 4 females; other monkeys were unaffected. In male monkeys, another alpha‐2 receptor agonist, guanfacine (0.01–1.0 mg/kg, i.v.), produced similar effects. In contrast, in 3 male rhesus monkeys, acute and chronic treatment with LFX increased choice of low cocaine doses. In addition, in 5 rhesus monkeys responding under a multiple FR food, PR cocaine schedule, LFX increased cocaine injections at doses that did not affect food‐reinforced responding. Taken together, these data indicate a limited effectiveness of alpha‐2 receptor agonists to decrease ongoing cocaine self‐administration. However, the potential of this class of drugs to reduce relapse in abstinent individuals should be studied further in models that specifically assess such effects.Support or Funding InformationDA10584, DA 17763, DA 06634
Abuse‐Related Effects of “Bath Salts” Mixtures: Studies with MDPV, Methylone, and Caffeine in Rats.
Authors: Collins Gregory T , Gannon Brenda M , Galindo Kayla I , Mesmin Melson P , Rice Kenner C 
Published: November 2023

The recreational use of synthetic cathinones has become a serious public health problem worldwide. In the US, “bath salts” products often contain MDPV (a monoamine transporter inhibitor) or methylone (a monoamine transporter substrate); however, preparations often contain mixtures of multiple synthetic cathinones, or mixtures of a synthetic cathinone and caffeine. In order to determine if the reinforcing effects of mixtures of “bath salts” constituents differed from the reinforcing effects of the constituents alone, adult male Sprague Dawley rats were trained to self‐administer either 0.032 mg/kg/inf MDPV or 0.32 mg/kg/inf methylone under a progressive ratio (PR) schedule of reinforcement. Drug mixtures were based on the concept of dose equivalence, with each pair of drugs evaluated at three ratios (3:1, 1:1, and 1:3) relative to the mean ED50 for each drug. Dose addition analyses were used to calculate predicted effect levels for an additive interaction at each dose pair of each combination of drugs using the Emax, ED50, and slope parameters derived from dose‐response curves obtained in individual rats. Although high levels of responding were maintained by each of the “bath salts” mixtures, the nature of the interaction varied depending upon the constituent drugs. For combinations containing a cathinone and caffeine (MDPV+caffeine and methylone+caffeine), the interactions were generally additive, however, when mixed at a 3:1 ratio of their ED50s the reinforcing effects of both sets of mixtures were found to be supra‐additive. Interestingly, although combining caffeine with MDPV appeared to only increase the potency of the mixture, combining caffeine and methylone significantly increased the reinforcing effectiveness of the a “bath salts” mixture beyond that which would be predicted for an additive interaction. Unlike with combinations of cathinones and caffeine, when MDPV was combined with methylone departures from additivity tended to occur in the sub‐additive direction, with the onset of toxicity observed with larger dose pairs of the MDPV+methylone mixtures. Together, these studies suggest that the reinforcing effects of binary mixtures containing common bath salts constituents (i.e., MDPV, methylone, and caffeine) are generally additive in nature; however, both supra‐additive (MDPV+caffeine and methylone+caffeine) and sub‐additive interactions (MDPV+methylone) can be observed. Although such interactions could account for the high rates of bath salts abuse, further study will be needed to determine if similar interactions exist between these and other bath salts constituents with regard to other abuse‐related and toxic effects.Support or Funding InformationThis study was supported by a National Institutes of Health (NIH) research grant (R01 DA039146) from the National Institute on Drug Abuse (NIDA), as well as the NIH Intramural Research Programs of NIDA and National Institute on Alcohol Abuse and Alcoholism (NIAAA).
Prior Treadmill Exercise Promotes Resilience in Traumatized Rats
Authors: Kochi Camila , Zaidi Safiyya , Liu Hesong , Atrooz Fatin , Dantoin Phoebe , Salim Samina 
Published: November 2023

Post‐traumatic stress disorder (PTSD) is a serious psychological condition induced by experiencing traumatic events. Interestingly, PTSD can be acquired not only from directly experiencing traumatic events but also from witnessing such events. Treatment and prevention strategies are limited. Animal studies have provided critical insights. Recently, we published a “Trauma Witness Model” (TWM) of rat and reported that witnessing traumatic events cause PTSD‐like behaviors including anxiety‐ and depression‐like behavior as well as learning‐memory deficits. TWM is a modified social defeat paradigm, which involves aggressive encounters between a large Long‐Evans male rat (resident) and a smaller Sprague‐Dawley male rat (intruder), resulting in intruder social defeat. The cage mate of the intruder designated as trauma witnessing rat (TW), is positioned to witness intruder defeat. Using this model, we examined beneficial role of moderate treadmill exercise in preventing TW‐induced behavioral impairments. Beneficial role of treadmill exercise has been reported in other models of stress. Male Sprague Dawley rats were allocated to five different groups: control (C), social defeat (SD), exercise (Ex), trauma witness (TW), and trauma witness with exercise (TWEx). The two exercised groups, Ex and TWEx, were subjected to a daily 30‐minute treadmill exercise regimen for 14 days. On day 15, the SD group was exposed to 7 days of direct trauma. The trauma witness groups, TW and TWEx, were strategically placed around the cage to witness the SD rats receive social defeat. On day 22, all groups were subjected to behavioral and cognitive tests including short‐term (STM) and long‐term (LTM) memory function, anxiety and depression‐like behaviors. TW and SD had the highest levels of anxiety and depression‐like behaviors compared to the other groups. In addition, TWEx had lower levels of anxiety and depression‐like behaviors compared to TW. STM and LTM remained unchanged. This study demonstrates that treadmill exercise provides resilience to trauma witness in a rodent model.Support or Funding InformationGrant Support: 2R15MH093918‐02
Investigating the role of the locus coeruleus‐noradrenergic system during social stress on neuroinflammation and resulting changes in serotonin
Authors: Moffitt Casey M , Finnell Julie E , Lombard Calliandra M , Wood Christopher S , Wood Susan K 
Published: November 2023

Repeated exposure to social stress is known to result in the emergence of depression. While depression is associated with dysregulation of norepinephrine (NE) and serotonin (5‐HT), the mechanism by which this occurs remains unknown. We have previously determined that a history of social stress enhances neuroinflammation in stress sensitive brain regions, proving causal to a depressive‐like phenotype in socially stressed rats. A growing body of evidence suggests that NE is capable of altering proinflammatory cytokine release (ie. IL‐1β) in the brain. Therefore, there were three major goals of this study: 1) to determine if a history of social defeat produced a sensitized neuroinflammatory response to a subsequent stressor within the serotonergic dorsal raphe (DR); 2) because IL‐1β is capable of decreasing 5‐HT synthesis, we sought to determine whether changes in IL‐β in the DR were related to changes in 5‐HT synthesis and 3) rats were treated with DSP‐4 (400μg/rat, icv), a selective retrograde NE neurotoxin that reduces NE levels in LC target regions (ie., DR), to determine the role of NE on stress‐induced IL‐1β levels in the DR and relative 5‐HT expression. Our initial studies identified sensitized stress‐induced proinflammatory cytokine expression in the brains of socially defeated rats compared with rats with a history of control. Furthermore, DSP‐4 significantly increased stress‐induced proinflammatory cytokines in the central amygdala a prominent LC target and induced anhedonia in the 2‐bottle choice sucrose preference test, regardless of stress history. This suggests that LC‐NE has inhibitory control over neuroinflammation in its target regions, including the DR. Since inflammation is known to increase the enzymatic activity of indoleamine‐2,3‐dioxygenase (IDO), resulting in a shift from 5‐HT synthesis to the production of kynurenine (Kyn), stress‐induced inflammation in the DR is likely associated with a concomitant increase in IDO activity and a reduction of 5‐HT. Together these data suggest that LC‐NE activity may suppress neuroinflammatory drive under conditions of stress and that impaired LC‐NE firing may serve as a mechanistic link between stress‐induced neuroinflammation, dysfunction in the 5‐HT system, and expression of depressive‐like behaviors. These studies seek to identify mechanisms involved in stress susceptibility, in order to reveal novel targets useful in the treatment of stress‐related psychosocial disorders.Support or Funding Information15SDG22430017 and P20GM103641
Repeated Social Defeat Stress Changes Peripheral Immune Status in Rats: Potential Effects on Basolateral Amygdala Function
Authors: Munshi Soumyabrata , Rosenkranz J. Amiel 
Published: November 2023

Chronic psychological stress is one of the most common triggers of clinical depression and anxiety, and many studies suggest involvement of the immune system in these effects. The basolateral amygdala (BLA), a key brain region involved in emotion, mediates many effects of stress on emotion and may be an intermediary in the link between immune function and depression. Repeated social defeat stress (RSDS) is a powerful model of social stress with known impact on immune function. The peripheral immune system includes pro‐inflammatory and anti‐inflammatory aspects that, as a whole, may exert very different influences on behavior. The aim of this study is (1) to determine the effect of RSDS on the balance between pro‐inflammatory and anti‐inflammatory aspects of peripheral immune function, and (2) to determine if a shift in this balance causes a change in BLA function. Adult male Sprague Dawley rats were exposed to the resident‐intruder model of RSDS using unfamiliar aggressor Long Evans rats for five consecutive days, or control handling. After three days, the following were evaluated: (a) peripheral circulating T‐cell counts and their intracellular cytokine profile (Th1, Th2) by flow‐cytometry, (b) pro‐ and anti‐inflammatory serum cytokine levels by ELISA, and (c) anxiety‐like behavior in the open field test (OFT). RSDS decreased the frequency of dual positive (DP, CD4+CD8+) T‐cells as well as the CD4+ T‐cells with no significant changes in that of the CD8+ T‐cells. Additionally, RSDS increased the frequency of dual negative (DN, CD4‐CD8‐) precursor T‐cells in the circulation. Frequency of CD4+ T‐cells positive for the Th2‐like (anti‐inflammatory) cytokine was increased with similar increase in those of the CD8+ T‐cells positive for the Tc2‐like (anti‐inflammatory) cytokine. RSDS also caused changes in many different serum cytokines. OFT showed that RSDS induced an increase in anxiety‐like behavior. To test whether a pro‐inflammatory state can induce a change in the BLA physiology, in vivo extracellular electrophysiological recordings were performed in a different set of rats that underwent peripheral immune challenge with interleukin‐1β. Interleukin‐1β caused a trend of a time‐dependent alteration of the evoked local field potential as well as alteration of the spontaneous neuronal firing‐rate in the BLA. Taken together, these data suggest that RSDS affects differentiation of peripheral circulatory T‐cells and shifts peripheral immune balance. In addition, a shift in immune balance impacts BLA neuronal activity. This could contribute to the effects of RSDS on anxiety behavior. The results have implications in understanding how chronic stress might alter BLA physiology by recruitment of the peripheral immune system.Support or Funding InformationNIH Grant MH084970 and MH109484 to JAR.
Caveolin‐2: Improves Longevity and Allows for Stress Adaptation in C. Elegans
Authors: Mehta Meghna D. , Schilling Jan M. , Mehta Ekta D. , Fridolfsson Heidi N. , Roth David M. , Patel Hemal H. 
Published: November 2023

IntroductionCaveolins are scaffolding proteins that are involved in stress adaptation via regulation of signal transduction and endocytosis. Three isoforms of caveolin (Cav‐1, Cav‐2, and Cav‐3) are expressed in mammalian cells, while C. elegans express only two (Cav‐1 and Cav‐2). Cav‐2 has conserved homology to the mammalian isoforms Cav‐1 and Cav‐3, with the amino acid region being 67% similar and 37% identical. As aging and diabetic studies are lengthy in mice, a model species such as C. elegans could qualify for high throughput evaluation of the role of caveolin in stress and adaptation since their lifespan is generally under 30 days. Benefits of C. elegans as a model organism are that their whole genome has been sequenced and that they are the only organism to have a complete connectome.HypothesisWe hypothesized that expression level of Cav‐2 in C. elegans is a major regulator of stress adaptation with increased expression leading to better, and decreased expression leading to worse stress response.MethodsWe generated C. elegans overexpressing Cav‐2 (Cav‐2 OE) gene through microinjection and transformation with a global promotor. The worms were grown on 1.7% agar plates containing E. coli OP50. We assessed the impact of the Cav‐2 gene on longevity, egg laying, and stress adaptation by comparing the N2 control with the Cav‐2 OE and Cav‐2 KO.ResultsCav‐2 OE worms showed a 13.3% increase in median lifespan compared to N2 controls and Cav‐2 KO worms (p<0.001, n=180, Log‐Rank Test) under normal conditions. Cav‐2 OE worms had a 28% and 41% increase in production of eggs compared to the N2 controls and Cav‐2 KO worms, respectively. Cav‐2 OE worms also had an 18% increase in the duration of egg laying compared to both N2 controls and Cav‐2 KO worms (p<0.0001, n=180, 2‐Way RM ANOVA). In order to examine the ability of C. elegans to adapt to stress, we induced stress by exposing the C. elegans to 2% glucose. Cav‐2 OE worms showed a 8% and 27% increase in lifespan compared to N2 controls and Cav‐2 KO worms, respectively (p<0.0001, n=180, Log‐Rank Test).ConclusionTaken together, our data suggests that Cav‐2 is a major regulator of longevity and stress adaptation in C. elegans and C. elegans may serve as an ideal model system to evaluate the impact of caveolin on human physiology and aging.Support or Funding InformationThis research was supported by funds from the UCSD Department of Anesthesiology.
Anti‐angiogenic Peptide Derived from Kinesin KIF13B Inhibits Trafficking of VEGFR2 to Endothelial Cell surface
Authors: Yamada Kaori , Malik Asrar B. 
Published: November 2023

Trafficking of VEGFR2 to the endothelial cell (EC) surface is required for VEGF‐induced angiogenesis. We found that the kinesin‐family plus‐end motor KIF13B transports VEGFR2 to the EC surface. VEGF induced phosphorylation on KIF13B, and activated KIF13B by increasing binding of KIF13B to VEGFR2, and KIF13B‐VEGFR2 complex to microtubule tracks. KIF13B depletion shunted VEGFR2 towards the lysosomal degradation pathway. KIF13B depletion also prevented VEGF‐mediated endothelial migration, capillary tube formation, and neo‐vascularization in mice, suggesting blockade of trafficking as a potential anti‐angiogenesis strategy.We developed a bioactive peptide based on VEGFR2‐binding domain of KIF13B, which competes specifically with VEGFR2‐binding of KIF13B, and thereby inhibits angiogenesis. The peptide termed a kinesin‐derived angiogenesis inhibitor (KAI) is a cell‐permeable, water‐soluble peptide, inhibiting EC migration, capillary network formation, and EC sprouting, in vitro. KAI also inhibited VEGF‐induced EC migration and tumor growth in human lung carcinoma xenografted in immunodeficient mice. Thus, we describe a novel class of peptides derived from the site of interaction of KIF13B with VEGFR2 that inhibit VEGFR2 trafficking and thereby starve cancer of blood supply.Support or Funding InformationThis work was supported by PPG HL060678, R01 HL045638, P01 HL077806, R01 HL090152, R01 HL118068, and R01 HL125350 to ABM, R56 HL128342 and 13SDG14680053 to KHY.
Mutagenesis study on the Ca2+ sensitivity of the SK2 channel
Authors: Siwiecki Sara Ann , Nam Young Woo , Whitmore Benjamin , Orfali Razan , Zhang Miao 
Published: November 2023

The cerebellar Purkinje Cells (PCs) are affected in many types of ataxias. The dysfunction of PCs, more specifically the loss of firing precision of PCs, is one of the primary mechanisms underlying the symptoms of ataxia. Disruptions of regular pacemaking activity of PCs have been identified in studies with mouse models of ataxias. Drugs that normalize the regular firing of PCs have been suggested as therapeutics for the symptom of ataxia patients. Small conductance Ca2+ activated potassium (SK) channels emerged as one of the principle ion channel involved in PCs' pacemaking. Over the past decade, positive allosteric modulators (PAMs) have been developed to target the SK channels. PAMs of SK channels have been shown to alleviate behavioral and neuro‐pathological symptoms in animal models of ataxias. In the SK2 channel, an intrinsically disordered fragment (IDF) at the proximal intracellular C‐terminus connects the transmembrane S6 domain and the CaM binding domain (CaMBD). The flexibility of the IDF makes it a perfect region for the modulation of SK channel activity. The PAMs such as NS309 stabilizes the IDF, and consequently facilitates the coupling between Ca2+ binding to CaM and opening of the channel. This observation motivated us to introduce mutations in the PAM binding pocket, which also result in changes in the Ca2+ sensitivity of SK channels.Support or Funding InformationAmerican Heart Association SDG Grant, National Ataxia Foundation YI‐SCA Grant to M.Z.