N-Isopropylbenzylamine-induced conditioned place preference, sensitization behaviour and self-administration in rodents.

N-Isopropylbenzylamine (N-ipb), a chain isomer of methamphetamine (METH) with similar physical properties, has been used as a substitute for METH in seized drug samples. However, the abuse potential of N-ipb remains unclear. Therefore, this study aimed to evaluate the abuse potential of N-ipb in comparison to METH, by using conditioned place preference (CPP), locomotor sensitization and intravenous self-administration tests. The results showed that N-ipb at a dose of 3 mg·kg-1 significantly induced CPP in mice, which was comparable to the effect of METH at 1 mg·kg-1 . Either acute or repeated N-ipb injections (1 or 3 mg·kg-1 ) failed to raise the locomotor activity. However, acute treatment with 10 mg·kg-1 N-ipb elevated the locomotor activity compared with saline, while chronic injection of 10 mg·kg-1 N-ipb induced a delayed and attenuated sensitization compared with 1 mg·kg-1 METH. Rats could acquire N-ipb self-administration at a dose of 1 mg·kg-1 ·infusion-1 , and a typical inverted U-shaped dose-response curve was obtained for N-ipb. The mean dose of N-ipb that maintained the maximum response was greater than that of METH, indicating that N-ipb is less potent for reinforcement than METH. In the economic behavioural analysis, comparison of essential values derived from the demand elasticity revealed that N-ipb is less efficacy as a reinforcer than METH. The present data demonstrate that N-ipb functions as a reinforcer and has a potential for abuse. However, the potency of psychomotor stimulation and the reinforcing effectiveness of N-ipb are lower than those of METH.

TRPV1 is a risk factor for sleep disturbance in patients with gastro-oesophageal reflux disease: a case control study.

BACKGROUND/AIMS: Gastro-oesophageal reflux disease (GORD) is a chronic high-morbidity disease with a bidirectional relationship with sleep disturbance (SD) that may occur via the transient receptor potential vanilloid type 1 receptor (TRPV1) in the oesophageal mucosa. Yet the related mechanism was still unclear, the aim of this study is to investigate whether TRPV1 is associated with the presence of SD in GORD patients. METHODS: A case-control study was performed. After the screening, A total of 88 subjects were assigned to GORD without sleep disturbance (GORD + NOSD, n = 28), GORD comorbid sleep disturbance (GORD + SD, n = 30) and matched healthy controls (n = 30). Mucosal tissue was obtained from the participants by digestive endoscopy, the levels of TRPV1 expressed in the oesophageal mucosa were detected via RT-qPCR and western blot in different groups, and the correlation between GORD and SD were also analysed. RESULTS: In this study, we found that the Gastroesophageal Reflux Disease Diagnostic Questionnaire (GerdQ) scores was positively correlated with Pittsburgh Sleep Quality Index (PSQI) scores but negatively correlated with total sleep time (TST). We also found that the level of TRPV1 expressed in the oesophageal mucosa of GORD + SD was significantly higher than GORD + NOSD patients, and they were all higher than healthy controls. CONCLUSION: The current study suggested a closer link exists between GORD and sleep disturbance, and TRPV1 in oesophageal mucosa may be a crucial factor affecting sleep in GORD patients.

Assessment of abuse potential of carfentanil.

Carfentanil, as a fentanyl analogue, is a potent synthetic opioid. It has been controlled in many countries, and its emergence has been highlighted by many recent reports. However, although discriminative stimulus effects of carfentanil in rats had been reported, its abuse potential has not been fully evaluated. In this study, we evaluated the abuse potential of carfentanil via the tests of conditioned place preference (CPP), drug self-administration and naloxone-precipitated opioid withdrawal assay, compared with fentanyl and heroin. Carfentanil exhibited significant place preference at a minimum dose of 1 µg/kg in mice, whereas fentanyl and heroin induced significant place preference at the minimum doses of 100 µg/kg and 1000 µg/kg, respectively. In the drug-substitution test in heroin self-administered rats (50 µg/kg/infusion), carfentanil and fentanyl acquired significant self-administrations above saline levels from 0.05-0.1 and 0.1-10.0 µg/kg/infusion, respectively. Carfentanil induced the maximum number of infusions at 0.1 µg/kg, whereas fentanyl and heroin at 1 and 25 µg/kg, respectively. In short, carfentanil showed the highest potency to induce CPP and self-administration. Furthermore, repeated treatment with escalating doses of carfentanil, fentanyl or heroin induced typical withdrawal symptoms in mice, including a greater number of jumping and weight loss than saline group. This indicated that carfentanil could produce physical dependence similar to fentanyl and heroin. Taken together, the present study demonstrated the higher abuse potential of carfentanil compared with fentanyl and heroin. The rank order of abuse potential for these compounds is carfentanil > fentanyl > heroin.

Seed priming with rutin enhances tomato resistance against the whitefly Bemisia tabaci.

Flavonoids are ubiquitously distributed in plants, showing pleiotropic effects in defense against abiotic and biotic stresses. Although it has been shown that seed priming with flavonoids can enhance plant resistance to abiotic stress, little is known about its potential to enhance plant tolerance to biotic stresses, especially for herbivorous insects. Here, we investigated whether treatment of tomato (Solanum lycopersicum) seeds with rutin improves plant resistance against the whitefly (Bemisia tabaci). Specifically, we measured the effect of rutin seed treatment on tomato seedling vigour, plant growth, feeding behavior and performance of B. tabaci on plants grown from control and rutin-treated seeds, and plant defense responses to B. tabaci attack. We found that seed treatment with different concentrations of rutin (viz 1, 2, 5, 10, and 20 mM) had minimal impact on shoot growth. Furthermore, seed treatment of rutin reduced the developmental rate of nymphs, the fecundity and feeding efficiency of adult females on plants grown from these seeds. The enhanced resistance of tomato against B. tabaci is closely associated with increased flavonoids accumulation, callose deposition and the expression of jasmonic acid (JA)-dependent defense genes. Additionally, callose deposition and expression of JA-dependent genes in tomato plants grown from rutin-treated seeds significantly increased upon B. tabaci infestation. These results suggest that seed treatment with rutin primes tomato resistance against B. tabaci, and are not accompanied by reductions in shoot growth. Defense priming by seed treatments may therefore be suitable for commercial exploitation.

2-Fluorodeschloroketamine has similar abuse potential as ketamine.

2-Fluorodeschloroketamine (2-FDCK) as a substitute for ketamine has emerged among drug abusers in recent years. However, 2-FDCK has not been controlled or regulated in many countries, which may be partly related to the lack of evidence on its abuse potential. In this study, we evaluated the abuse potential of 2-FDCK via the tests of the conditioned place preference (CPP), locomotor sensitization, drug self-administration and drug discrimination using ketamine as a reference. 2-FDCK induced significant CPP at a minimum dose of 3 mg/kg in mice, an effect comparable with that of ketamine (3 mg/kg). Acute injections of 2-FDCK or ketamine at 30 mg/kg enhanced locomotor activity. Repeated treatments with this dose of 2-FDCK and ketamine induced locomotor sensitization after withdrawal. 2-FDCK readily induced self-administration with 0.5 mg/kg/infusion, the same dose for ketamine, and induced the highest seeking response at 1 mg/kg. Drug discrimination test showed that 2-FDCK dose-dependently substitute for ketamine with comparable ED50 to ketamine in substitution testing. Taken together, these results strongly suggested that 2-FDCK has an abuse potential comparable with ketamine.

Tropisetron Facilitates Footshock Suppression of Compulsive Cocaine Seeking.

BACKGROUND: The hallmark characteristics of the murine model of drug addiction include the escalation of cocaine consumption and compulsive punishment-resistant drug seeking. In this study, we evaluated the motivation for drug seeking in cocaine self-administering rats exposed to an escalated dosing regimen that endeavored to mimic the characteristic of escalating drug intake in human addicts. Tropisetron is a 5-HT3 receptor antagonist and α7-nicotinic receptor partial agonist. Utilizing rats trained on the escalated-dosing regimen, we examined the effects of tropisetron on control over compulsive drug-seeking behavior that was defined as footshock-resistant lever pressing. METHODS: Rats were trained to self-administer cocaine with incremental-infusion doses (from 0.6 to 2.4 mg/kg/infusion) across training sessions (3 h/session) or with a long-access paradigm (i.e., 0.6 mg/kg/infusion, 6 h/d training session). The drug-seeking motivations of 2 groups were estimated by the patterns of drug intake and progressive-ratio schedule. The compulsivity for drug seeking of the group with an escalated dose was further evaluated using the footshock-associated seeking-taking chain task. RESULTS: The rats trained on the dose-escalated protocol achieved the same levels of motivated drug seeking as those subjected to a long-access paradigm, as indicated by cocaine intake per training session and breakpoints on a progressive ratio schedule. Tropisetron attenuated compulsive behavior of rats when pressing of the seeking lever potentially led to footshock. Intriguingly, tropisetron did not change the motivation to seek cocaine when footshock was absent. Tropisetron had no effect on locomotor activities or saccharin self-administration. CONCLUSIONS: These results demonstrate that tropisetron restored control over compulsive cocaine seeking, and they indicate that 5-HT3/α7-nicotinic receptors may be potential therapeutic targets for relieving compulsive drug seeking.

The Effects of 4-Methylethcathinone on Conditioned Place Preference, Locomotor Sensitization, and Anxiety-Like Behavior: A Comparison with Methamphetamine.

BACKGROUND: 4-Methylethcathinone is a drug that belongs to the second generation of synthetic cathinones, and recently it has been ranked among the most popular "legal highs". Although it has similar in vitro neurochemical actions to other drugs such as cocaine, the behavioral effects of 4-methylethcathinone remain to be determined. METHODS: The addictive potential and locomotor potentiation by 4-methylethcathinone were investigated in rats using the conditioned place preference and sensitization paradigm. Methamphetamine was used as a positive control. Because synthetic cathinones can have psychological effects, we also examined anxiety-like behavior using the elevated plus maze. RESULTS: A conditioning dose of 10 mg/kg 4-methylethcathinone was able to induce conditioned place preference and reinstatement (following 2 weeks of withdrawal). Acute or repeated injections of 4-methylethcathinone at 3 or 10mg/kg failed to alter locomotor activity. At 30 mg/kg, however, acute 4-methylethcathinone increased locomotor activity compared with saline, while chronic 4-methylethcathinone induced a delayed and attenuated sensitization compared with methamphetamine. Additionally, repeated daily injections of 4-methylethcathinone (30 mg/kg) reduced, whereas methamphetamine increased time spent by rats in the open arm of an elevated plus maze compared with saline injections. Interestingly, a 2-week withdrawal period following chronic injections of 4-methylethcathinone or methamphetamine increased time spent in the open arm in all rats. CONCLUSIONS: The rewarding properties of 4-methylethcathinone were found to be dissociated from its effects on locomotor activity. Additionally, chronic 4-methylethcathinone use may trigger abnormal anxious behaviors. These behavioral effects caused by 4-methylethcathinone appear to last even after a withdrawal period.

Synaptic glutamate spillover due to impaired glutamate uptake mediates heroin relapse.

Reducing the enduring vulnerability to relapse is a therapeutic goal in treating drug addiction. Studies with animal models of drug addiction show a marked increase in extrasynaptic glutamate in the core subcompartment of the nucleus accumbens (NAcore) during reinstated drug seeking. However, the synaptic mechanisms linking drug-induced changes in extrasynaptic glutamate to relapse are poorly understood. Here, we discovered impaired glutamate elimination in rats extinguished from heroin self-administration that leads to spillover of synaptically released glutamate into the nonsynaptic extracellular space in NAcore and investigated whether restoration of glutamate transport prevented reinstated heroin seeking. Through multiple functional assays of glutamate uptake and analyzing NMDA receptor-mediated currents, we show that heroin self-administration produced long-lasting downregulation of glutamate uptake and surface expression of the transporter GLT-1. This downregulation was associated with spillover of synaptic glutamate to extrasynaptic NMDA receptors within the NAcore. Ceftriaxone restored glutamate uptake and prevented synaptic glutamate spillover and cue-induced heroin seeking. Ceftriaxone-induced inhibition of reinstated heroin seeking was blocked by morpholino-antisense targeting GLT-1 synthesis. These data reveal that the synaptic glutamate spillover in the NAcore results from reduced glutamate transport and is a critical pathophysiological mechanism underling reinstated drug seeking in rats extinguished from heroin self-administration.

eIF2α dephosphorylation in basolateral amygdala mediates reconsolidation of drug memory.

Maladaptive memories elicited by exposure to environmental stimuli associated with drugs of abuse are often responsible for relapse among addicts. Interference with the reconsolidation of drug memory can inhibit drug seeking. Previous studies have indicated that the dephosphorylation of the eukaryotic initiation factor 2 α-subunit (eIF2α) plays an important role in synaptic plasticity and long-term memory consolidation, but its role in the reconsolidation of drug memory remains unknown. The amygdala is required for the reconsolidation of a destabilized drug memory after retrieval of drug-paired stimuli. Here, we used conditioned place preference (CPP) and self-administration procedures to determine whether amygdala eIF2α dephosphorylation is required for the reconsolidation of morphine and cocaine memories in rats. We found that the levels of eIF2α phosphorylation (Ser51) and activating transcription factor 4 (ATF4) were decreased after reexposure to a previously morphine- or cocaine-paired context (i.e., a memory retrieval procedure) in the basolateral amygdala (BLA) but not in the central amygdala. Intra-BLA infusions of Sal003, a selective inhibitor of eIF2α dephosphorylation, immediately after memory retrieval disrupted the reconsolidation of morphine- or cocaine-induced CPP, leading to a long-lasting suppression of drug-paired stimulus-induced craving. Advanced knockdown of ATF4 expression in the BLA by lentivirus-mediated short-hairpin RNA blocked the disruption of the reconsolidation of morphine-induced CPP induced by Sal003 treatment. Furthermore, inhibition of eIF2α dephosphorylation in the BLA immediately after light/tone stimulus retrieval decreased subsequent cue-induced heroin-seeking behavior in the self-administration procedure. These results demonstrate that eIF2α dephosphorylation in the BLA mediates the memory reconsolidation of drug-paired stimuli.

Attenuated methamphetamine-induced locomotor sensitization in serotonin transporter knockout mice is restored by serotonin 1B receptor antagonist treatment.

Repeated administration of methamphetamine (METH) enhances acute locomotor responses to METH administered in the same context, a phenomenon termed as 'locomotor sensitization'. Although many of the acute effects of METH are mediated by its influences on the compartmentalization of dopamine, serotonin systems have also been suggested to influence the behavioral effects of METH in ways that are not fully understood. The present experiments examined serotonergic roles in METH-induced locomotor sensitization by assessing: (a) the effect of serotonin transporter (SERT; Slc6A4) knockout (KO) on METH-induced locomotor sensitization; (b) extracellular monoamine levels in METH-treated animals as determined by in-vivo microdialysis; and (c) effects of serotonin (5-HT) receptor antagonists on METH-induced behavioral sensitization, with focus on effects of the 5-HT1B receptor antagonist SB 216641 and a comparison with the 5-HT2 receptor antagonist ketanserin. Repeated METH administration failed to induce behavioral sensitization in homozygous SERT KO (SERT-/-) mice under conditions that produced substantial sensitization in wild-type or heterozygous SERT KO (SERT+/-) mice. The selective 5-HT1B antagonist receptor SB 216641 restored METH-induced locomotor sensitization in SERT-/- mice, whereas ketanserin was ineffective. METH-induced increases in extracellular 5-HT (5-HTex) levels were substantially reduced in SERT-/- mice, although SERT genotype had no effect on METH-induced increases in extracellular dopamine. These experiments demonstrate that 5-HT actions, including those at 5-HT1B receptors, contribute to METH-induced locomotor sensitization. Modulation of 5-HT1B receptors might aid therapeutic approaches to the sequelae of chronic METH use.

Heroin relapse requires long-term potentiation-like plasticity mediated by NMDA2b-containing receptors.

Persistent relapse to addictive drugs constitutes the most challenging problem in addiction therapy, and is linked to impaired prefrontal cortex regulation of motivated behaviors involving the nucleus accumbens. Using a rat model of heroin addiction, we show that relapse requires long-term potentiation (LTP)-like increases in synaptic strength in the prefrontal cortex projection to the nucleus accumbens. The increased synaptic strength was paralleled by dendritic spine enlargement in accumbens spiny neurons and required up-regulated surface expression of NMDA2b-containing receptors (NR2B). Accordingly, blocking NR2B before reinstating heroin-seeking prevented the induction of LTP-like changes in spine remodeling and synaptic strength, and inhibited heroin relapse. These data show that LTP-like neuroplasticity in prefrontal-accumbens synapses is initiated by NR2B stimulation and strongly contributes to heroin relapse. Moreover, the data reveal NR2B-containing NMDA receptors as a previously unexplored therapeutic target for treating heroin addiction.

Reversing cocaine-induced synaptic potentiation provides enduring protection from relapse.

Cocaine addiction remains without an effective pharmacotherapy and is characterized by an inability of addicts to inhibit relapse to drug use. Vulnerability to relapse arises from an enduring impairment in cognitive control of motivated behavior, manifested in part by dysregulated synaptic potentiation and extracellular glutamate homeostasis in the projection from the prefrontal cortex to the nucleus accumbens. Here we show in rats trained to self-administer cocaine that the enduring cocaine-induced changes in synaptic potentiation and glutamate homeostasis are mechanistically linked through group II metabotropic glutamate receptor signaling. The enduring cocaine-induced changes in measures of cortico-accumbens synaptic and glial transmission were restored to predrug parameters for at least 2 wk after discontinuing chronic treatment with the cystine prodrug, N-acetylcysteine. N-acetylcysteine produced these changes by inducing an enduring restoration of nonsynaptic glutamatergic tone onto metabotropic glutamate receptors. The long-lasting pharmacological restoration of cocaine-induced glutamatergic adaptations by chronic N-acetylcysteine also caused enduring inhibition of cocaine-seeking in an animal model of relapse. These data mechanistically link nonsynaptic glutamate to cocaine-induced adaptations in excitatory transmission and demonstrate a mechanism to chronically restore prefrontal to accumbens transmission and thereby inhibit relapse in an animal model.

Role of amygdala in drug memory.

Drug addiction is a chronic brain disorder with the hallmark of a high rate of relapse to compulsive drug seeking and drug taking even after long-term abstinence. Addiction has been considered as an aberrant memory that has been termed "addiction memory." Drug-related memory plays a critical role in the maintenance of learned addictive behaviors and emergence of relapse. Disrupting these long-lasting memories by administering amnestic agents or other manipulations during specific phases of drug memory is a promising strategy for relapse prevention. Recent studies on the processes of drug addiction and relapse have demonstrated that the amygdala is involved in associative drug addiction learning processes. In this review, we focus on preclinical studies that used conditioned place preference and self-administration models to investigate the differential roles of the amygdala in each phase of drug-related memory, including acquisition, consolidation, retrieval, reconsolidation, and extinction. These studies indicate that the amygdala plays a critical role in both cue-associative learning and the expression of cue-induced relapse to drug-seeking behavior.

Reduced LTP and LTD in prefrontal cortex synapses in the nucleus accumbens after heroin self-administration.

Addiction changes prefrontal cortex regulation of the nucleus accumbens, including reduced ability to induce long-term potentiation (LTP) and long-term depression (LTD). This important potential mechanism of impaired prefrontal regulation of behaviour has been shown only for cocaine. Here we show that animals trained to self-administer heroin demonstrate impaired LTP and LTD in the core of the nucleus accumbens following in vivo stimulation of the prelimbic prefrontal cortex. These data indicate that compromised synaptic plasticity in prefrontal to accumbens projections is a common feature of at least two distinct classes of addictive drug.

Role of mGluR5 neurotransmission in reinstated cocaine-seeking.

In animal models of addiction, reducing glutamate stimulation of the metabotropic glutamate receptor 5 (mGluR5) inhibits drug-seeking. The present study used the reinstatement model of cocaine-seeking to show that blockade of mGluR5 directly in the core subcompartment of the nucleus accumbens (NAcore) prevented both conditioned cue- and cocaine-reinstated drug-seeking. Consistent with this finding, microinjection of the mGluR5 agonist (RS)-2-chloro-5-hydroxyphenylglycine into the NAcore produced modest reinstatement of lever pressing when given alone and significantly potentiated cue-induced reinstatement. Homer proteins are contained in the post-synaptic density and regulate mGluR5 intracellular signaling and trafficking to the membrane. Microinjecting a membrane permeable peptide antagonist of Homer binding to mGluR5 into the NAcore also inhibited cue- and cocaine-reinstated lever pressing. However, this peptide did not change the surface expression of mGluR5, indicating that the peptide inhibitor did not alter the surface trafficking of mGluR5. Taken together, these data show that mGluR5 inhibition and stimulation in the NAcore can regulate cocaine-seeking, and demonstrate that one mechanism for this effect is via interactions with Homer proteins.

Flavonoid-producing tomato plants have a direct negative effect on the zoophytophagous biological control agent Orius sauteri.

Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is often used for biological control of small arthropod pests in greenhouse vegetable production systems in Asia. In addition to feeding on arthropod prey, O. sauteri consumes small quantities of plant material. Previous studies demonstrated that tomato plant chemistry confers antixenosis resistance to phloem-feeding whiteflies, but the potential nontarget effects of phytochemicals on the beneficial predator O. sauteri are unknown. Comparison of O. sauteri confined to near-isogenic lines (NILs) of tomatoes producing high levels of flavonoids (NIL-purple hypocotyl; resistant to whiteflies) and low levels of flavonoids (NIL-green hypocotyl; susceptible to whiteflies) revealed that O. sauteri had reduced oviposition, nymphal survival, and development on resistant plants, even if they were also provided with prey that did not feed on the host plant. Moreover, O. sauteri showed a significant ovipositional preference in choice assays, laying significantly more eggs on susceptible than on resistant plants. Molecular gut content analysis using the specific chloroplast trnL gene from tomato confirmed that adult and immature O. sauteri feed on both resistant and susceptible genotypes, and feeding behavior assays revealed that resistance did not affect plant feeding or prey acceptance by O. sauteri adults. These results demonstrate a direct negative effect of phytochemicals on a nontarget beneficial species and indicate that resistance mediated by phytochemicals can affect organisms that do not solely feed on phloem sap. The results also indicate that the mode of action and the potential ecological effects of phytochemical-mediated resistance are broader than previously recognized.

Benzodiazepine-Receptor Agonist Utilization in Outpatients with Anxiety Disorder: A Retrospective Study Based on Electronic Healthcare Data from a Large General Tertiary Hospital.

Benzodiazepine-receptor agonists (BZRAs), including benzodiazepines (BZDs) and drugs related to BZDs (Z-drugs), are commonly used for anxiety, but often have side effects. We retrospectively investigated the utilization and prescription characteristics of BZRAs for patients with anxiety disorders in a large tertiary care general hospital between 2018 and 2021, based on electronic healthcare records. We also examined the pattern of simultaneous consumption of multiple BZRA drugs, and the diseases coexisting with anxiety that are associated with this. The numbers of patients and BZRA prescriptions increased over the 4 years. Moreover, 7195 prescriptions from 694 patients contained two or more BZRAs, of which 78.08% contained both BZDs and Z-drugs, 19.78% contained multiple BZDs, and 2.14% contained multiple Z-drugs. For anxiety patients with concomitant Alzheimer's disease or Parkinson's disease, and dyslipidemia, they were more likely to consume multiple BZRAs simultaneously, whereas patients with concomitant insomnia, depression, hypertension, diabetes, or tumors were less likely to consume multiple BZRAs (all p < 0.05). Furthermore, older patients who consume multiple BZRAs simultaneously may have higher probabilities of long-term drug use. Better interventions supporting standardized BZD utilization may be needed to minimize the side effects of inappropriate BZRA administration.

The high frequency oscillation in orbitofrontal cortex is susceptible to phenethylamine psychedelic 25C-NBOMe in male rats.

Serotoninergic psychedelics induced extensive alterations in perception and cognition, which has been attributable to its disruptive effect on oscillatory rhythms of prefrontal cortex. However, there is a lack of information how serotoninergic psychedelics affect the intra-prefrontal network, which intrinsically interact to accomplish perceptual processing. Uncovering the altered neural network caused by psychedelics helps to understand the mechanisms of their psychoactive effects and contribute to develop biological markers of psychedelic effects. In present study, we investigated the effects of substituted phenethylamine psychedelic 25C-NBOMe on neural oscillations in the intra-prefrontal and hippocampal-prefrontal network. The effective dose of 25C-NBOMe (0.1 mg/kg) disrupting sensorimotor gating in male Sprague-Dawley rats was used to observe its effects on neural oscillations in the prelimbic cortex, anterior cingulate cortex, orbitofrontal cortex (OFC) and hippocampus CA1. The power of high frequency oscillation (HFO, 120-150 Hz) was potentiated by 25C-NBOMe selectively in the OFC, with peaking at 20-30 min after treatment. 25C-NBOMe strengthened HFO coherence within the intra-prefrontal, rather than hippocampal-prefrontal network. Potentiated HFO in the OFC had a strong positive correlation with the strengthened inter-prefrontal HFO coherence by 25C-NBOMe. The 25C-NBOMe-induced alterations of rhythmic patterns were prevented by pre-treatment with selective serotonin 2A receptor antagonist MDL100,907. These results demonstrate that OFC rhythmic activity in HFO is relatively susceptible to substituted phenethylamine and potentially drives drug-induced rhythmic coherence within intra-prefrontal regions. Our findings provide additional insight into the neuropathophysiology of the psychoactive effects of psychedelics and indicate that the altered HFO might be applied as a potential biological marker of psychedelic effect.

Flavonoid production in tomato mediates both direct and indirect plant defences against whiteflies in tritrophic interactions.

BACKGROUND: The role of plant flavonoids in direct defences against chewing and sap-sucking herbivorous insects has been extensively characterized. However, little is known about flavonoid-mediated tritrophic interactions between plants, herbivorous insects and natural enemies. In this study, we investigated how flavonoids modulate plant-insect interactions in a tritrophic system involving near-isogenic lines (NILs) of cultivated tomato (Solanum lycopersicum) with high (line NIL-purple hypocotyl [PH]) and low (line NIL-green hypocotyl [GH]) flavonoid levels, with a generalist herbivore whitefly (Bemisia tabaci) and its predatory bug (Orius sauteri). RESULTS: By contrasting levels of tomato flavonoids (direct defence) while manipulating the presence of predators (indirect defence), we found that high production of flavonoids in tomato was associated with a higher inducibility of direct defences and a stronger plant resistance to whitefly infestation and stimulated the emissions of induced volatile organic compounds, thereby increasing the attractiveness of B. tabaci-infested plants to the predator O. sauteri. Furthermore, suppression of B. tabaci population growth and enhancement of plant growth were mediated directly by the high production of flavonoids and indirectly by the attraction of O. sauteri, and the combined effects were larger than each effect individually. CONCLUSION: Our results show that high flavonoid production in tomato enhances herbivore-induced direct and indirect defences to better defend against herbivores in tritrophic interactions. Thus, the development of transgenic plants may present an opportunity to utilize the beneficial role of flavonoids in integrated pest management, while simultaneously maintaining or improving resistance against other pests and pathogens. © 2023 Society of Chemical Industry.

The effects of serotonergic psychedelics in synaptic and intrinsic properties of neurons in layer II/III of the orbitofrontal cortex.

RATIONALE: Serotonergic psychedelics show promise in the treatment of psychiatric disorders, including obsessive-compulsive disorder. Dysfunction of the orbitofrontal cortex (OFc) has been implicated in the pathophysiology of compulsive behavior, which might be a key region for the efficacy of psychedelics. However, the effects of psychedelics on the neural activities and local excitation/inhibition (E/I) balance in the OFc are unclear. OBJECTIVES: This study aimed to investigate how 25C-NBOMe, a substituted phenethylamine psychedelic, regulated the synaptic and intrinsic properties of neurons in layer II/III of the OFc. METHODS: Acute brain slices containing the OFc of adult male Sprague Dawley rats were used for ex vivo whole-cell recording. The synaptic and intrinsic properties of neurons were monitored using voltage and current clamps, respectively. Electrically evoked action potential (eAP) was used to measure synaptic-driven pyramidal activity. RESULTS: 25C-NBOMe enhanced spontaneous neurotransmission at glutamatergic synapses but diminished that in GABAergic synapses through the 5-HT2A receptor. 25C-NBOMe also increased both evoked excitatory currents and evoked action potentials. Moreover, 25C-NBOMe promoted the excitability of pyramidal neurons but not fast-spiking neurons. Either inhibiting G protein-gated inwardly rectifying potassium channels or activating protein kinase C significantly obstructed the facilitative effect of 25C-NBOMe on the intrinsic excitability of pyramidal neurons. CONCLUSIONS: This work reveals the multiple roles of 25C-NBOMe in modulating synaptic and neuronal function in the OFc, which collectively promotes local E/I ratios.