Single-cell transcriptome analyses reveal critical regulators of spermatogonial stem cell fate transitions.

BACKGROUND: Spermatogonial stem cells (SSCs) are the foundation cells for continual spermatogenesis and germline regeneration in mammals. SSC activities reside in the undifferentiated spermatogonial population, and currently, the molecular identities of SSCs and their committed progenitors remain unclear. RESULTS: We performed single-cell transcriptome analysis on isolated undifferentiated spermatogonia from mice to decipher the molecular signatures of SSC fate transitions. Through comprehensive analysis, we delineated the developmental trajectory and identified candidate transcription factors (TFs) involved in the fate transitions of SSCs and their progenitors in distinct states. Specifically, we characterized the Asingle spermatogonial subtype marked by the expression of Eomes. Eomes+ cells contained enriched transplantable SSCs, and more than 90% of the cells remained in the quiescent state. Conditional deletion of Eomes in the germline did not impact steady-state spermatogenesis but enhanced SSC regeneration. Forced expression of Eomes in spermatogenic cells disrupted spermatogenesis mainly by affecting the cell cycle progression of undifferentiated spermatogonia. After injury, Eomes+ cells re-enter the cell cycle and divide to expand the SSC pool. Eomes+ cells consisted of 7 different subsets of cells at single-cell resolution, and genes enriched in glycolysis/gluconeogenesis and the PI3/Akt signaling pathway participated in the SSC regeneration process. CONCLUSIONS: In this study, we explored the molecular characteristics and critical regulators of subpopulations of undifferentiated spermatogonia. The findings of the present study described a quiescent SSC subpopulation, Eomes+ spermatogonia, and provided a dynamic transcriptional map of SSC fate determination.

The silk gland proteome of Stenopsyche angustata provides insights into the underwater silk secretion.

Caddisworms (Trichoptera) spin adhesive silks to construct a variety of underwater composite structures. Many studies have focused on the fibroin heavy chain of caddisworm silk and found that it contains heavy phosphorylation to maintain a stable secondary structure. Besides fibroins, recent studies have also identified some new silk proteins within caddisworm silk. To better understand the silk composition and its secretion process, this study reports the silk gland proteome of a retreat-building caddisworm, Stenopsyche angustata Martynov (Trichoptera, Stenopsychidae). Using liquid chromatography tandem mass spectrometry (LC-MS/MS), 2389 proteins were identified in the silk gland of S. angustata, among which 192 were predicted as secreted silk proteins. Twenty-nine proteins were found to be enriched in the front silk gland, whereas 109 proteins were enriched in the caudal silk gland. The fibroin heavy chain and nine uncharacterized silk proteins were identified as phosphorylated proteins. By analysing the sequence of the fibroin heavy chain, we found that it contains 13 Gly/Thr/Pro-rich regions, 12 Val/Ser/Arg-rich regions and a Gly/Arg/Thr-rich region. Three uncharacterized proteins were identified as sericin-like proteins due to their larger molecular weights, signal peptides and repetitive motifs rich in serine. This study provides valuable information for further clarifying the secretion and adhesion of underwater caddisworm silk.

Glutamatergic neurons in ventral pallidum modulate heroin addiction via epithalamic innervation in rats.

Glutamatergic neurons in ventral pallidum (VPGlu) were recently reported to mediate motivational and emotional behavior, but its role in opioid addiction still remains to be elucidated. In this study we investigated the function of VPGlu in the context-dependent heroin taking and seeking behavior in male rats under the ABA renewal paradigm. By use of cell-type-specific fiber photometry, we showed that the calcium activity of VPGlu were inhibited during heroin self-administration and context-induced relapse, but activated after extinction in a new context. The drug seeking behavior was accompanied by the decreased calcium signal of VPGlu. Chemogenetic manipulation of VPGlu bidirectionally regulated heroin taking and seeking behavior. Anterograde tracing showed that the lateral habenula, one of the epithalamic structures, was the major output region of VPGlu, and its neuronal activity was consistent with VPGlu in different phases of heroin addiction and contributed to the motivation for heroin. VPGlu axon terminals in LHb exhibited dynamic activity in different phases of heroin addiction. Activation of VPGlu-LHb circuit reduced heroin seeking behavior during context-induced relapse. Furthermore, the balance of excitation/inhibition from VP to LHb was shifted to enhanced glutamate transmission after extinction of heroin seeking motivation. Overall, the present study demonstrated that the activity of VPGlu was involved in the regulation of heroin addiction and identified the VPGlu-LHb pathway as a potential intervention to reduce heroin seeking motivation.

Deep learning enables automatic adult age estimation based on CT reconstruction images of the costal cartilage.

OBJECTIVE: Adult age estimation (AAE) is a challenging task. Deep learning (DL) could be a supportive tool. This study aimed to develop DL models for AAE based on CT images and compare their performance to the manual visual scoring method. METHODS: Chest CT were reconstructed using volume rendering (VR) and maximum intensity projection (MIP) separately. Retrospective data of 2500 patients aged 20.00-69.99 years were obtained. The cohort was split into training (80%) and validation (20%) sets. Additional independent data from 200 patients were used as the test set and external validation set. Different modality DL models were developed accordingly. Comparisons were hierarchically performed by VR versus MIP, single-modality versus multi-modality, and DL versus manual method. Mean absolute error (MAE) was the primary parameter of comparison. RESULTS: A total of 2700 patients (mean age = 45.24 years ± 14.03 [SD]) were evaluated. Of single-modality models, MAEs yielded by VR were lower than MIP. Multi-modality models generally yielded lower MAEs than the optimal single-modality model. The best-performing multi-modality model obtained the lowest MAEs of 3.78 in males and 3.40 in females. On the test set, DL achieved MAEs of 3.78 in males and 3.92 in females, which were far better than the MAEs of 8.90 and 6.42 respectively, for the manual method. For the external validation, MAEs were 6.05 in males and 6.68 in females for DL, and 6.93 and 8.28 for the manual method. CONCLUSIONS: DL demonstrated better performance than the manual method in AAE based on CT reconstruction of the costal cartilage. CLINICAL RELEVANCE STATEMENT: Aging leads to diseases, functional performance deterioration, and both physical and physiological damage over time. Accurate AAE may aid in diagnosing the personalization of aging processes. KEY POINTS: • VR-based DL models outperformed MIP-based models with lower MAEs and higher R2 values. • All multi-modality DL models showed better performance than single-modality models in adult age estimation. • DL models achieved a better performance than expert assessments.

Upregulation of dynorphin/kappa opioid receptor system in the dorsal hippocampus contributes to morphine withdrawal-induced place aversion.

Aversive emotion of opioid withdrawal generates motivational state leading to compulsive drug seeking and taking. Kappa opioid receptor (KOR) and its endogenous ligand dynorphin have been shown to participate in the regulation of aversive emotion. In the present study, we investigated the role of dynorphin/KOR system in the aversive emotion following opioid withdrawal in acute morphine-dependent mice. We found that blockade of KORs before pairing by intracerebroventricular injection of KOR antagonist norBNI (20, 40 µg) attenuated the development of morphine withdrawal-induced conditioned place aversion (CPA) behavior. We further found that morphine withdrawal increased dynorphin A expression in the dorsal hippocampus, but not in the amygdala, prefrontal cortex, nucleus accumbens, and thalamus. Microinjection of norBNI (20 µg) into the dorsal hippocampus significantly decreased morphine withdrawal-induced CPA behavior. We further found that p38 MAPK was significantly activated in the dorsal hippocampus after morphine withdrawal, and the activation of p38 MAPK was blocked by pretreatment with norBNI. Accordingly, microinjection of p38 MAPK inhibitor SB203580 (5 µg) into the dorsal hippocampus significantly decreased morphine withdrawal-produced CPA behavior. This study demonstrates that upregulation of dynorphin/KOR system in the dorsal hippocampus plays a critical role in the formation of aversive emotion associated with morphine withdrawal, suggesting that KOR antagonists may have therapeutic value for the treatment of opioid withdrawal-induced mood-related disorders.

Prelimbic cortex dynorphin/κ opioid receptor system modulates methamphetamine-induced cognitive impairment.

Chronic exposure to methamphetamine (METH) causes severe and persistent cognitive impairment. The present study aimed to investigate the role of dynorphin/κ opioid receptor (KOR) system in the development of METH-induced cognitive impairment. We found that mice showed significant cognitive impairment in the novel object recognition test (NOR) following daily injections of METH (10 mg/kg) for seven consecutive days. Systemic blockade of KOR prevented METH-induced cognitive impairment by pretreatment of the selective KOR antagonist norBNI (10 mg/kg, i.p.) or KOR deletion. Then, significant increased dynorphin and KOR mRNA were observed exclusively in prelimbic cortex (PL) other than infralimbic cortex. Finally, microinjection with norBNI into PL also improved cognitive memory in METH-treated mice using NOR and spontaneous alternation behaviour test. Our results demonstrated that dynorphin/KOR system activation in PL may be a possible mechanism for METH-induced cognitive impairment and shed light on KOR antagonists as a potential neuroprotective agent against the cognitive deficits induced by drug abuse.

[Chemical constituents from whole herb of Hedyotis scandens].

This study aimed to investigate the chemical constituents in the water extract of the whole herb of Hedyotis scandens by silica gel, ODS, and MCI column chromatographies together with preparative high-performance liquid chromatography(HPLC). The structures of isolated constituents were identified by NMR, HR-ESI-MS, etc. Thirteen compounds were isolated and identified as methyl 4-benzoyloxy-3-methoxybenzeneacetate(1), 4-benzoyloxy-3-methoxybenzeneacetic acid(2), 3-(4-hydroxy-3-methoxyphenyl)-propanoic acid(3), salicylic acid(4), 3-hydroxy-4-methoxypyridine(5), syringic acid(6), hydroxycinnamic acid(7),(R)-6-methyl-4,6-bis(4-methylpent-3-enyl)cyclohexa-1,3-dienecarbaldehyde(8), 1,2-bis(4-hydroxy-3-methoxyphenyl)-1,3-propanediol(9), 1H-indole-3-carboxaldehyde(10), isoscopoletin(11), syringaresinol(12), and pinoresinol(13). Among them, compounds 1 and 2 were new phenolic acid compounds, compounds 3-5, 8-11, and 13 were isolated from this genus for the first time, and compounds 6, 7, and 12 were obtained from H. scandens for the first time. The activity test showed that compounds 1 and 10 had a certain inhibitory effect on Mycobacterium smegmatis, with MIC_(50) values of 58.5 and 33.3 µg·mL~(-1), respectively.

Antinociceptive activities and mechanism of action of Cepharanthine.

Cepharanthine is an alkaloid that isolated from Stephania cepharantha Hayata, however，its analgesic properties are unclear and the molecular targets that mediating Cepharanthine-induced analgesia are not explored yet. In the current study, mice pain models including hot plate, acetic acid-induced writhing and formalin tests were conducted to evaluate the antinociceptive actions of Cepharanthine. [3H]-ligand competitive binding assay was applied to determine the binding affinity and selectivity of Cepharanthine at κ, µ and δ opioid receptors. Cepharanthine-induced constipation was investigated using the small intestinal transit test. The results showed that intraperitoneal injection of Cepharanthine produced potent antinociception with an ED50 value of 24.5 mg/kg in the acetic acid-induced writhing test. In the formalin test, Cepharanthine produced moderate antinociception with the maximum analgesic activity of 42.6 ± 11.3% in phase I and 60.1 ± 7.7% in phase Ⅱ, respectively. Cepharanthine had no effects in the hot plate test. In vitro radioligand binding assay, Cepharanthine exhibited a high affinity for µ opioid receptors with a Ki value of 80 nM, without binding to κ and δ opioid receptors. Correspondingly, Cepharanthine-mediated antinociceptive effects were antagonized by pretreatment with opioid receptor antagonist naloxone. Cepharanthine also decreased the small intestine propulsion rates in the small intestinal transit test. Together, this study firstly demonstrates that Cepharanthine produces potent antinociception in acetic acid-induced visceral pain and moderate antinociception in formalin-induced inflammatory pain, and its mechanism of action may be through activation of µ opioid receptors.

Ube2b-dependent degradation of DNMT3a relieves a transcriptional brake on opiate-induced synaptic and behavioral plasticity.

Compelling evidence suggests that synaptic structural plasticity, driven by remodeling of the actin cytoskeleton, underlies addictive drugs-induced long-lasting behavioral plasticity. However, the signaling mechanisms leading to actin cytoskeleton remodeling remain poorly defined. DNA methylation is a critical mechanism used to control activity-dependent gene expression essential for long-lasting synaptic plasticity. Here, we provide evidence that DNA methyltransferase DNMT3a is degraded by the E2 ubiquitin-conjugating enzyme Ube2b-mediated ubiquitination in dorsal hippocampus (DH) of rats that repeatedly self-administrated heroin. DNMT3a degradation leads to demethylation in CaMKK1 gene promotor, thereby facilitating CaMKK1 expression and consequent activation of its downstream target CaMKIα, an essential regulator of spinogenesis. CaMKK1/CaMKIα signaling regulates actin cytoskeleton remodeling in the DH and behavioral plasticity by activation of Rac1 via acting Rac guanine-nucleotide-exchange factor ßPIX. These data suggest that Ube2b-dependent degradation of DNMT3a relieves a transcriptional brake on CaMKK1 gene and thus activates CaMKK1/CaMKIα/ßPIX/Rac1 cascade, leading to drug use-induced actin polymerization and behavior plasticity.

Alteration of twinfilin1 expression underlies opioid withdrawal-induced remodeling of actin cytoskeleton at synapses and formation of aversive memory.

Exposure to drugs of abuse induces alterations of dendritic spine morphology and density that has been proposed to be a cellular basis of long-lasting addictive memory and heavily depend on remodeling of its underlying actin cytoskeleton by the actin cytoskeleton regulators. However, the actin cytoskeleton regulators involved and the specific mechanisms whereby drugs of abuse alter their expression or function are largely unknown. Twinfilin (Twf1) is a highly conserved actin-depolymerizing factor that regulates actin dynamics in organisms from yeast to mammals. Despite abundant expression of Twf1 in mammalian brain, little is known about its importance for brain functions such as experience-dependent synaptic and behavioral plasticity. Here we show that conditioned morphine withdrawal (CMW)-induced synaptic structure and behavior plasticity depends on downregulation of Twf1 in the amygdala of rats. Genetically manipulating Twf1 expression in the amygdala bidirectionally regulates CMW-induced changes in actin polymerization, spine density and behavior. We further demonstrate that downregulation of Twf1 is due to upregulation of miR101a expression via a previously unrecognized mechanism involving CMW-induced increases in miR101a nuclear processing via phosphorylation of MeCP2 at Ser421. Our findings establish the importance of Twf1 in regulating opioid-induced synaptic and behavioral plasticity and demonstrate its value as a potential therapeutic target for the treatment of opioid addiction.

Dezocine as a potent analgesic: overview of its pharmacological characterization.

Dezocine, a synthetic opioid, introduced in 1970s as an analgesic, was redeveloped for relieving moderate to severe pain by Yangtze River Pharmaceutical Group in China in 2009. To date, dezocine occupies 45% of China's opioid analgesic market. Along with dezocine being a dominated painkiller, a certain amount of research was conducted to elucidate dezocine's action. In this review we summarize the current knowledge on the receptor, preclinical and clinical pharmacology of dezocine. Briefly, preclinical data show that dezocine is effective under varying pain conditions, particularly chronic neuropathic pain and cancer pain, through activation of opioid receptors, and inhibition of norepinephrine reuptake. Clinical data establish the effectiveness of dezocine either as a primary analgesic for postoperative pain management or a supplement for balanced analgesia. The receptor profile of dezocine is different from known pure µ agonists, and allows it to be used in combination with other opioids for additivity in efficacy or lower incidence of adverse effects.

Amygdala dynorphin/κ opioid receptor system modulates depressive-like behavior in mice following chronic social defeat stress.

Major depression disorder is a severe and recurrent neuropsychological disorder characterized by lowered mood and social activity and cognitive impairment. Owing to unclear molecular mechanisms of depression, limited interventions are available in clinic. In this study we investigated the role of dynorphin/κ opioid receptor system in the development of depression. Mice were subjected to chronic social defeat stress for 14 days. Chronic social defeat stress induced significant social avoidance in mice characterized by decreased time duration in the interaction zone and increased time duration in the corner zone. Pre-administration of a κ opioid receptor antagonist norBNI (10 mg/kg, i.p.) could prevent the development of social avoidance induced by chronic social defeat stress. Social avoidance was not observed in κ opioid receptor knockout mice subjected to chronic social defeat stress. We further revealed that social defeat stress activated c-fos and ERK signaling in the amygdala without affecting the NAc, hippocampus and hypothalamus, and ERK activation was blocked by systemic injection of norBNI. Finally, the expression of dynorphin A, the endogenous ligand of κ opioid receptor, was significantly increased in the amygdala following social defeat stress; microinjection of norBNI into the amygdala prevented the development of depressive-like behaviors caused by social defeat stress. The present study demonstrates that upregulated dynorphin/κ opioid receptor system in the amygdala leads to the emergence of depression following chronic social defeat stress, and sheds light on κ opioid receptor antagonists as potential therapeutic agents for the prevention and treatment of depression following chronic stress.

Novel selective κ agonists SLL-039 and SLL-1206 produce potent antinociception with fewer sedation and aversion.

SLL-039 (N-cyclopropylmethyl-7α-4'-(N'-benzoyl) amino-phenyl-6,14-endoethano-tetrahydronorthebaine) and SLL-1206 (N-cyclopropylmethyl-7α-3'-(p-methoxybenzyl) amino-phenyl-6,14-endoethano-tetrahydronorthebaine) are two 4,5-epoxymorphinan-based high selective κ receptor agonists that we recently discovered. In the present study we characterized their pharmacological properties in comparison with arylacetamide-based typical κ agonist U50,488H. We showed that both SLL-039 and SLL-1206 produced potent and long-lasting antinociceptive actions in three different rodent models of pain via activation of κ opioid receptor. In hot-plate assay, the antinociceptive potency of SLL-039 and SLL-1206 increased about 11-and 17.3-fold compared to U50,488H and morphine, respectively, with ED50 values of 0.4 mg/kg. Following repeated administration, SLL-1206, SLL-039, and U50,488H all developed analgesic tolerance tested in hot-plate assay. U50,488H and SLL-039 produced antipruritic effects in a dose-dependent manner, whereas SLL-1206 displayed some antipruritic effects only at very low doses. In addition, SLL-1206 was capable of decreasing morphine-induced physical dependence. More importantly, SLL-039 and SLL-1206 at effective analgesic doses did not cause sedation and conditioned place aversion (CPA), whereas U50,488H did. In comparison with SLL-039, SLL-1206 caused similar antinociceptive responses, but fewer sedation and CPA. In conclusion, our results suggest that SLL-039 and SLL-1206 have potential to be developed as novel analgesic agents, and 4,5-expoxymorphinan scaffold is an attractive structure for the development of selective κ agonists with fewer side effects.

Paternal hypoxia exposure impairs fertilization process and preimplantation embryo development.

Environmental hypoxia exposure causes fertility problems in human and animals. Compelling evidence suggests that chronic hypoxia impairs spermatogenesis and reduces sperm motility. However, it is unclear whether paternal hypoxic exposure affects fertilization and early embryo development. In the present study, we exposed male mice to high altitude (3200 m above sea level) for 7 or 60 days to evaluate the effects of hypoxia on sperm quality, zygotic DNA methylation and blastocyst formation. Compared with age-matched controls, hypoxia-treated males exhibited reduced fertility after mating with normoxic females as a result of defects in sperm motility and function. Results of in vitro fertilization (IVF) experiments revealed that 60 days' exposure significantly reduced cleavage and blastocyst rates by 30% and 70%, respectively. Immunohistochemical staining of pronuclear formation indicated that the pronuclear formation process was disturbed and expression of imprinted genes was reduced in early embryos after paternal hypoxia. Overall, the findings of this study suggested that exposing male mice to hypoxia impaired sperm function and affected key events during early embryo development in mammals.

Improved protein purification system based on C-terminal cleavage of Npu DnaE split intein.

A purification system was constructed with the N-segment of the Npu DnaE split intein as an affinity ligand immobilized onto an epoxy-activated medium and the C-segment used as the cleavable tag fusing target protein. The affinity properties of C-tagged proteins adsorbed on IN affinity chromatography medium were studied with GFP as a model target protein. The saturated adsorption capacity and dynamic adsorption capacity reached 51.9-21.0 mg mL-1, respectively. With this system, two model proteins, GFP and alcohol dehydrogenase (ADH), has been successfully taglessly purified with regulation of Zn2+ and DTT. The yield, purification factor and purity of purified tagless GFP reached 39, 11.7 and 97%, respectively; while these values for purified tagless ADH were 38.2, 6.8 and 91%, respectively. These results showed that the system for Npu DnaE split intein-mediated affinity adsorption and in situ cleavage is a potential platform for recombinant protein production.

Genome-Wide Identification of the Expansin Gene Family and Its Potential Association with Drought Stress in Moso Bamboo.

Expansins, a group of cell wall-loosening proteins, are involved in cell-wall loosening and cell enlargement in a pH-dependent manner. According to previous study, they were involved in plant growth and abiotic stress responses. However, information on the biological function of the expansin gene in moso bamboo is still limited. In this study, we identified a total of 82 expansin genes in moso bamboo, clustered into four subfamilies (α-expansin (EXPA), ß-expansin (EXPB), expansin-like A (EXLA) and expansin-like B (EXPB)). Subsequently, the molecular structure, chromosomal location and phylogenetic relationship of the expansin genes of Phyllostachys edulis (PeEXs) were further characterized. A total of 14 pairs of tandem duplication genes and 31 pairs of segmented duplication genes were also identified, which may promote the expansion of the expansin gene family. Promoter analysis found many cis-acting elements related to growth and development and stress response, especially abscisic acid response element (ABRE). Expression pattern revealed that most PeEXs have tissue expression specificity. Meanwhile, the expression of some selected PeEXs was significantly upregulated mostly under abscisic acid (ABA) and polyethylene glycol (PEG) treatment, which implied that these genes actively respond to expression under abiotic stress. This study provided new insights into the structure, evolution and function prediction of the expansin gene family in moso bamboo.

Influence of Soil Properties and Aging on Antimony Toxicity for Barley Root Elongation.

The study explored the Sb toxicity by investigating the impacts of 10% and 20% effective concentrations (EC10 and EC20, respectively) of Sb on the inhibition of barley root elongation in 21 Chinese soils with a wide range of physicochemical properties after aging for 3 months. The results demonstrated that various soil properties profoundly influenced the Sb toxicity which was ranged from 201-2506 mg Sb kg-1 to 323-2973 mg Sb kg-1 under EC10 and EC20, respectively. Soil sand fraction was a significant soil factor responsible for elevating Sb bioavailability. The bioavailable Sb concentration accounted for 2.08%-11.94% of total Sb content in all 21 soil samples and the decreased Sb bioavailability in this study was attributed to soil properties including soil clay fraction, amorphous and crystalloid iron, and oxides of manganese and aluminum. The findings would contribute in developing Sb toxicity threshold for establishing standard for Sb regulation in crop production.

ACC to Dorsal Medial Striatum Inputs Modulate Histaminergic Itch Sensation.

Itch is an unpleasant sensation that initiates scratching behavior. The itch-scratch reaction is a complex phenomenon that implicates supraspinal structures required for regulation of sensory, emotional, cognitive, and motivational aspects. However, the central mechanisms underlying the processing of itch and the interplay of the supraspinal regions and spinal cord in regulating itch-scratch processes are poorly understood. Here, we have shown that the neural projections from anterior cingulate cortex (ACC) to dorsal medial striatum (DMS) constitute a critical circuit element for regulating itch-related behaviors in the brains of male C57BL/6J mice. Moreover, we demonstrate that ACC-DMS projections selectively modulate histaminergic, but not nonhistaminergic, itch-related behavior. Furthermore, photoactivation of ACC-DMS projections has also no significant effects on pain behavior induced by thermal, mechanical, and chemical stimuli except for a relief on inflammatory pain evoked by formalin and complete Freund's adjuvant. We further demonstrate that the dorsal spinal cord exerts an inhibitory effect on itch signal from ACC-DMS projections through B5-I neurons, which represent a population of spinal inhibitory interneurons that mediate the inhibition of itch. Therefore, this study presents the first evidence that the ACC-DMS projections modulate histaminergic itch-related behavior and reveals an interplay between the supraspinal and spinal levels in histaminergic itch regulation.SIGNIFICANCE STATEMENT This study reveals that the projections from anterior cingulate cortex (ACC) to dorsal medial striatum (DMS) constitute a supraspinal circuit for modulation of histaminergic, but not nonhistaminergic, itch. Manipulation of ACC-DMS projections has no effect on acute pain sensation. Furthermore, the dorsal spinal cord exerts an inhibitory effect on itch signal from ACC-DMS projections through B5-I neurons. Understanding the supraspinal itch circuits is of great significance in the development of new therapies for chronic itch-related intractable diseases.

The Adsorption Behavior of Atrazine in Common Soils in Northeast China.

The objective of this study was to evaluate the adsorption capacity of atrazine and the effects of different environmental conditions such as temperature, pH, Ca2+ and biochar on the adsorption characteristics of atrazine in different types of soil using the intermittent adsorption method. The kinetic experiment showed that the adsorption of atrazine in albic, black and saline-alkaline soils reached equilibrium within 24 h. In the thermodynamics experiment, the Freundlich model effectively described the adsorption characteristics of atrazine in all three types of soil, indicating that the adsorption process forms multi-molecular layers. Lower soil pH conditions were more favorable for the absorption of atrazine. The addition of appropriate concentrations of Ca2+ or biochar could promote the adsorption of atrazine by the soil. Biochar could promote the fixation of atrazine in soils.

The Small GTPase Rac1 Contributes to Extinction of Aversive Memories of Drug Withdrawal by Facilitating GABAA Receptor Endocytosis in the vmPFC.

Extinction of aversive memories has been a major concern in neuropsychiatric disorders, such as anxiety disorders and drug addiction. However, the mechanisms underlying extinction of aversive memories are not fully understood. Here, we report that extinction of conditioned place aversion (CPA) to naloxone-precipitated opiate withdrawal in male rats activates Rho GTPase Rac1 in the ventromedial prefrontal cortex (vmPFC) in a BDNF-dependent manner, which determines GABAA receptor (GABAAR) endocytosis via triggering synaptic translocation of activity-regulated cytoskeleton-associated protein (Arc) through facilitating actin polymerization. Active Rac1 is essential and sufficient for GABAAR endocytosis and CPA extinction. Knockdown of Rac1 expression within the vmPFC of rats using Rac1-shRNA suppressed GABAAR endocytosis and CPA extinction, whereas expression of a constitutively active form of Rac1 accelerated GABAAR endocytosis and CPA extinction. The crucial role of GABAAR endocytosis in the LTP induction and CPA extinction is evinced by the findings that blockade of GABAAR endocytosis by a dynamin function-blocking peptide (Myr-P4) abolishes LTP induction and CPA extinction. Thus, the present study provides first evidence that Rac1-dependent GABAAR endocytosis plays a crucial role in extinction of aversive memories and reveals the sequence of molecular events that contribute to learning experience modulation of synaptic GABAAR endocytosis.SIGNIFICANCE STATEMENT This study reveals that Rac1-dependent GABAAR endocytosis plays a crucial role in extinction of aversive memories associated with drug withdrawal and identifies Arc as a downstream effector of Rac1 regulations of synaptic plasticity as well as learning and memory, thereby suggesting therapeutic targets to promote extinction of the unwanted memories.