Oxytetracycline changes the behavior of zebrafish larvae by inhibiting NMDA receptors.

Oxytetracycline (OTC), a tetracycline antimicrobial, is one of the antimicrobial drugs frequently used in the aquaculture and livestock industries. Due to its extensive usage and emissions, OTC has been identified as a significant new emerging pollutant (EP) in a number of environments. OTC frequently causes toxic effects on the central nervous system, but it can be challenging to monitor, and it is still unclear how these toxicities are caused. We used bioinformatic analysis techniques to screen for OTC targets and discovered that NMDA receptors are potential targets of OTC neurotoxicity. To confirm this finding, we exposed zebrafish embryos to 5 mg/L OTC-containing rearing water from 2-hour post fertilization (hpf) to 8-day post fertilization (dpf), performed spontaneous movement and light-dark stimulation assays at 6 and 8 dfp, and discovered that OTC inhibited locomotor activity and attenuated anxiety-like responses in zebrafish larvae. Meanwhile, the qPCR and immunofluorescence staining results suggested that OTC inhibited the expression of multiple subtypes of NMDA receptors (grin1a, grin1b, grin2bb, grin2ca) and induced apoptosis in the brains of zebrafish embryos. Simultaneous administration of NMDA, an NMDA receptor agonist, completely antagonized the inhibitory neurobehavioral changes in zebrafish larvae, as well as the downregulation of N-methyl-D-aspartate (NMDA) receptor expression and apoptosis in the embryonic brains caused by OTC exposure. In conclusion, OTC exhibited significant inhibitory neurobehavioral toxicity in zebrafish larvae during early development, which may be dependent on its suppression of NMDA receptor activity and expression. Furthermore, OTC-induced neurodevelopmental toxicity may be associated with NMDA receptor-regulated neuronal apoptosis.

Pharmacy student's perceptions, behaviours and attitudes toward virtual reality simulation.

Aims: The definition of virtual reality simulation (VRS) used for study is the recreation of realistic simulation in a fully online situation with an immersive environment for learning an activity. The study aims to evaluate pharmacy students' perspectives, behavioral and attitude characteristics in the process of VRS course requiring practical skills. Materials and methods: This cross-sectional study was based on quantitative questionnaires analysis. A five-point Likert Scale (rating from 1 = Strongly Disagree; 2 = Disagree; 3 = Neutral; 4 = Agree; 5 = Strongly Agree) was utilized to measure the extent to which the students agrees on 30 statements comprised in A-E sections related to VRS. The validity and reliability of the questionnaire were studied by the Cronbach's Alpha calculation. Results: A total of 119 junior and senior pharmacy students, aged 18-25, participated in this study. There is no significant gender difference (P > 0.05) and grade difference (P > 0.05) in mean perception score, mean attitude score, mean behavior score and comparison score respectively. Most pharmacy students had positive perception that VRS could help them in practical ability (61.4 %), autonomous learning (68.9 %) and theoretical knowledge (61.4 %). Nevertheless, less than half the students agreed that VRS courses were indispensable (44.5 %) and needed to be increased (42.9 %). Moreover, the 'disagree' statement (33.6 %) exceeded 'agree' statement (27.7 %) about the question of whether preferring VRS courses to lab teaching. Interestingly, a significant positive correlation that was observed between mean perception score and mean attitude score (r = 0.76, p < 0.001), mean comparison (r = 0.68, p < 0.001) and mean behavior (r = 067, p < 0.001), which revealed that students who thought VRS was beneficial were more likely to accept it. Conclusion: The study highlights the need to establish an interactive, immersive and measurable VRS courses. It is suggested that good interaction between the faculty and student, technology improvement and blended programmatic assessment should be involved in challenges for implementing VRS courses.

The effects of all-trans retinoic acid on prednisolone-induced osteoporosis in zebrafish larvae.

Glucocorticoids (GCs) are extensively used as anti-inflammatory and immunosuppressive medications in the long-term treatment of rheumatic disorders, respiratory diseases, renal diseases, and organ transplantation. Prolonged use of GCs can reduce bone mineral density, leading to osteoporosis (Glucocorticoid Induced Osteoporosis, GIOP) and fracture. All-trans retinoic acid (ATRA) is an active vitamin A metabolite that regulates embryonic development and adult organ function. ATRA has been found in studies to enhance osteogenesis. To examine the interventional effects of ATRA on GIOP and the mechanisms of ATRA activities, we first performed bioinformatic analysis to identify potential gene targets of ATRA. Zebrafish larvae were recruited as experimental animals, and the frequently used GC, prednisolone, was administered to larvae to construct a GIOP model. We evaluated the influence of exogenous ATRA on the activities of bone metabolic enzymes, the expression of genes linked to osteoblasts and osteoclasts, and the restoration of bone mineral density and bone mass in GIOP zebrafish larvae. Furthermore, we studied the influence of RBM14, a transcriptional coactivator and negative reciprocal factor of ATRA, on the regulation of osteoblastic gene expression during the anti-GIOP process of ATRA using the morpholino knockdown approach. The findings of bone metabolic enzyme activity (alkaline phosphatase, ALP and tartrate-resistant acid phosphatase, TRAP) and expression assays of osteoblastic marker genes (Runx2a, Runx2b, SP7, Csf1a, RANKL, and CTSK) indicated that ATRA had bidirectional effects on osteogenesis. However, in the GIOP model, ATRA reversed the GIOP-induced osteoporosis phenotype by inhibiting the GIOP-induced suppression of osteoblastic metabolic enzyme (ALP) activities and osteoblastic marker gene expression (Runx2a, Runx2b, and SP7), and this antagonism was concentration-dependent. We also observed that ATRA inhibited RBM14 expression in zebrafish larvae, while ATRA alone and RBM14 knockdown showed a consistent induction of osteoblast marker gene expression, implying that ATRA's inhibitory effect on RBM14 expression may underlie ATRA's osteogenic effects. Based on these data, we postulated that ATRA may ameliorate GIOP by decreasing RBM14 expression, thereby enhancing osteoblastic marker gene expression.

Traditional Chinese Herbal Medicine for Allergic Diseases: A Review.

The prevalence of allergic disorders has increased in recent years, lowering patients' quality of life and increasing the demand for drugs to treat these diseases. Western drugs such as glucocorticoids, antihistamines, and leukotrienes are routinely utilized in clinics. However, drawbacks like high recurrence rates and adverse effects limit their use. As one of the most promising natural medicine systems, traditional Chinese medicine offers distinct benefits in treating allergic illnesses, such as maintaining long-term treatment, preventing disease recurrence, and producing fewer adverse reactions. We analyzed and discussed recent developments in traditional Chinese medicine used in allergic diseases from three perspectives: Chinese herbal formula, Chinese patent medicine, and active ingredients of traditional Chinese medicine, and explained their main components, efficacy, and mechanisms of action. We also reviewed the modification of Chinese herbal formulas and the combined application of Chinese medicine with Western medicine or nonpharmaceutical therapies. Traditional Chinese medicines are becoming increasingly important in treating allergic disorders. Improving traditional Chinese herbal formulas and developing safe and effective Chinese patent medicines are currently the most pressing and important aspects of research on traditional Chinese medicine.

Toxic effects of exogenous retinoic acid on the neurodevelopment of zebrafish (Danio rerio) embryos.

Endogenous retinoic acid (RA) is essential for embryonic development and maintaining adult physiological processes. Human-caused RA residues in the environment threaten the survival of organisms in the environment. We employed zebrafish as a model to explore the developmental impacts of excess RA. We used exogenous RA to raise the amount of RA signal in the embryos and looked at the effects of excess RA on embryonic morphological development. Upregulation of the RA signal significantly reduced embryo hatching and increased embryo malformation. To further understand the neurotoxic impact of RA signaling on early neurodevelopment, we measured the expression of neurodevelopmental marker genes and cell death and proliferation markers in zebrafish embryos. Exogenous RA disrupted stem cell (SC) and neuron marker gene expression and exacerbated apoptosis in the embryos. Furthermore, we looked into the links between the transcriptional coactivator RBM14 and RA signaling to better understand the mechanism of RA neurotoxicity. There was a negative interaction between RA signaling and the transcription coactivator RBM14, and the morpholino-induced RBM14 down-regulation can partially block the effects of RAR antagonist BMS493-induced RA signaling inhibition on embryonic malformation and cell apoptosis. In conclusion, exogenous RA causes neurodevelopmental toxicity, and RBM14 may be involved in this neurotoxic process.

Suppressive effect of triadimefon, a triazole fungicide, on spatial learning and reference memory in rats.

Although some central effects of triadimefon, a triazole fungicide, have been reported, its effects on spatial memory have not been examined. In this study, we used the Morris water maze to study the effect of triadimefon on spatial learning and memory in rats. To elucidate the mechanism of this effect, we also measured the retinoic acid concentration in the hippocampus by high-performance liquid chromatography. Our data showed that triadimefon inhibited spatial learning and impaired spatial reference memory, and decreased hippocampal retinoic acid concentration. There is evidence that triadimefon can regulate the metabolism of retinoic acid, which serves a critical function in the development and maintenance of spatial memory. Therefore, we speculate that the reduction in hippocampal retinoic acid concentration induced by triadimefon might be responsible for its suppressive effect on spatial learning and reference memory.

Effects of norfloxacin exposure on neurodevelopment of zebrafish (Danio rerio) embryos.

In view of the wide application of fluoroquinolones (FQs), a group of broad-spectrum synthetic antibacterial agents, and their large ingress into the environment, the toxic effects on non-target organisms caused by FQs have received great attention. In this study, we used zebrafish embryo as a model, measured the general toxic effects of norfloxacin, a commonly used FQs, and investigated the effects of norfloxacin on the neurodevelopment of zebrafish embryos. Our data showed that norfloxacin significantly inhibited the hatching rate of zebrafish embryos, and increased the mortality and malformation rate of the embryos. To discuss the developmental neurotoxicity of norfloxacin, we measured the expression of several stem cell and neuron lineage markers in the zebrafish embryos. We found that norfloxacin exposure inhibited the expression of GFAP (glial cell marker), and enhanced the expression of Sox 2 (stem cell marker) and Eno2 (mature neuron marker). By measuring the level of active Caspase 3 and the expression ratio of Bax to Bcl2, we discovered that norfloxacin induced obvious cell apoptosis in the brain of zebrafish embryos. To explore the mechanism of the developmental neurotoxic effects of norfloxacin, we applied MK-801, a non-competitive NMDA receptors antagonist, to block the actions of NMDA receptors. The results indicated that MK-801 could rescue the upregulated cell apoptosis and disrupted balance of neuro-glial differentiation induced by norfloxacin in the brain of zebrafish embryos. Our results suggest that the activation of NMDA receptors mediates the developmental neurotoxicity of norfloxacin.

Expression of RALDHs (ALDH1As) and CYP26s in human tissues and during the neural differentiation of P19 embryonal carcinoma stem cell.

Retinoic acid (RA) plays a critical role in embryonic development and function maintenance of vital organs in adult. Subtle regulation of RA signaling is relied on spatio-temporal control of RA synthesis and catabolism. In this study, we investigated the expression patterns of RA synthetases RALDHs and metabolic enzymes CYP26s in multiple human tissues, and this study revealed unique expression pattern for every isoform from these two enzyme families. And it was worth noting that there were evident differences between fetal brain and adult brain in the expression of RALDHs and CYP26s. To investigate the dynamic expression of RALDH isoforms and CYP26 isoforms during neural differentiation, we applied a P19 embryonal carcinoma stem cell neural differentiation model. And during P19 cell neural differentiation induced by all trans-retinoic acid (ATRA) and cell aggregate formation, RALDH1, RALDH2, CYP26A1, and CYP26B1 could be notably upregulated by ATRA, and keeping the high-level expression of RALDH1 and RALDH2 was dependent on the further neural differentiation, but not continuous ATRA induction. RALDH3 transcription could not be directly induced by ATRA, and obvious upregulation of its transcription initiated at the late stage of ATRA induction or after the removement of ATRA implied its neural differentiation-dependent expression pattern. CYP26C1 transcription was significantly repressed by ATRA, and this downregulation also showed a neural differentiation-dependent pattern, in respect that CYP26C1 expression was kept in low-level even after the withdrawal of ATRA.

Contributions of nucleus accumbens core and shell GluR1 containing AMPA receptors in AMPA- and cocaine-primed reinstatement of cocaine-seeking behavior.

Glutamate signaling in the nucleus accumbens influences reinstatement of previously extinguished cocaine-seeking behavior in rats. Whether or not region specific glutamate signaling in the nucleus accumbens contributes to reinstatement of cocaine-seeking behavior is not known. We investigated whether directly stimulating ionotropic glutamate receptors (GluRs) within the nucleus accumbens core or shell would differentially influence renewed cocaine-seeking behavior following extinction training. We also tested the hypothesis that GluR1 subunit (GluR1) containing alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) receptors in the nucleus accumbens core and not the shell regulate reinstatement of previously extinguished cocaine-seeking behavior. Microinjection of AMPA into the nucleus accumbens shell and the nucleus accumbens core dose-dependently elicited significant cocaine-seeking behavior. Administration of antisense oligonucleotides (AS) directed against GluR1 subunit mRNA into the core and shell disrupted AMPA- and cocaine-primed reinstatement--with the most pronounced effects seen in the nucleus accumbens shell. These results demonstrate that GluRs in the nucleus accumbens core and shell influence AMPA- and cocaine-primed reinstatement, yet the nucleus accumbens shell exerts a prepotency over the nucleus accumbens core.

Black agouti (ACI) rats show greater drug- and cue-induced reinstatement of methamphetamine-seeking behavior than Fischer 344 and Lewis rats.

Fischer 344 (F344) and Lewis (LEW) rats differ in methamphetamine self-administration (SA) and methamphetamine-induced reinstatement of previously extinguished behavior. We sought to determine whether genetic background also influences methamphetamine reinforcement efficacy, conditioned reinstatement, and methamphetamine-primed reinstatement of responding in F344, LEW, and Black Agouti (ACI) rats. We implanted rats with jugular catheters and trained them to self-administer methamphetamine (0.06 mg/kg/infusion) under a progressive ratio (PR) schedule of reinforcement during daily 2-h SA sessions. A compound stimulus (light+tone; LT) was paired with each infusion. Dose-dependent intake was determined for each rat. Rats then entered the extinction phase of the experiment where responding resulted in no programmed consequences. Following extinction sessions, rats underwent conditioned reinstatement testing. For conditioned reinstatement, rats received response-contingent presentations of the LT and no methamphetamine. Last, methamphetamine-primed reinstatement test sessions where conducted where subjects received experimenter delivered infusions of methamphetamine (0.06, 0.12, or 0.24 mg/kg). The strains did not differ in PR responding across the doses tested. The ACI rats demonstrated the highest behavioral output during extinction training, conditioned- and methamphetamine-primed reinstatement of previously extinguished behavior compared to the other strains. These data suggest that genetic background differentially influences extinction, conditioned reinstatement and methamphetamine-primed reinstatement in rats.

Different patterns of pharmacological reinstatement of cocaine-seeking behavior between Fischer 344 and Lewis rats.

RATIONALE: Fischer 344 (F344) and Lewis (LEW) rats differ in cocaine self-administration behaviors. Whether or not these inbred strains of rats differ in pharmacological reinstatement of cocaine-seeking behavior is unknown. OBJECTIVES: The purpose of the present study was to determine if inbred strains of rats demonstrate differences in alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) and cocaine-induced reinstatement of previously extinguished cocaine-seeking behavior. METHODS: F344 and LEW rats received indwelling jugular catheters, bilateral guide cannula aimed at the nucleus accumbens core, and were trained to lever press for 0.5 mg/kg intravenous cocaine during 2-h self-administration sessions. Following 14 sessions, rats underwent extinction sessions, where previously reinforced lever pressing resulted in no programmed consequences. Just prior to beginning extinction session 7, rats received an intracranial infusion of saline. Lever pressing was not reinforced. During subsequent extinction sessions, rats received AMPA injections (0.2, 0.4, or 0.6 nM). Dosing order was determined by a within-subject Latin square design. At least two extinction sessions separated each AMPA session. Rats then underwent cocaine-induced reinstatement test sessions (lever pressing was not reinforced). Rats received passive intravenous cocaine (0.0, 0.5, 1.0, or 2.0 mg/kg) after being placed in the experimental chamber. At least two extinction sessions separated each cocaine-prime session, and subjects were tested at each dose according to a within-subjects Latin square design. RESULTS: LEW rats demonstrated blunted maximal responding to AMPA-induced reinstatement and heightened sensitivity to cocaine-induced reinstatement compared with F344 rats. CONCLUSIONS: This study demonstrates that inbred strains differ in pharmacological reinstatement of cocaine-seeking behavior.

Differences in extinction responding and reinstatement of methamphetamine-seeking behavior between Fischer 344 and Lewis rats.

Fischer 344 (F344) and Lewis (LEW) rats differ in a number of self-administration behaviors. Whether or not these strains differ in methamphetamine-primed reinstatement of extinguished responding is unknown. F344 and LEW rats were trained to self-administer intravenous (i.v.) methamphetamine (0.06 mg/kg) during daily 2-h limited access sessions for 14 days. Following methamphetamine self-administration, subjects underwent a minimum of 6 extinction sessions where responding on the previously active lever resulted in no programmed consequences. Following extinction sessions, we evaluated strain and dose dependency of methamphetamine-primed (0.06, 0.12, or 0.24 mg/kg/i.v.) reinstatement of responding. All subjects received each dose once. Dosing order was determined by utilizing a within-subjects Latin square design. We found partial strain differences in daily methamphetamine self-administration. In addition, F344 rats responded significantly more during the first extinction session compared LEW rats. Last, the LEW rats demonstrated a heightened propensity to reinstate responding following methamphetamine priming injections compared to F344 rats. Our results suggest that genetic background influences differences in methamphetamine-seeking behaviors in rats.

Negative effects of retinoic acid on stem cell niche of mouse incisor.

The continuous growth of mouse incisors depends on epithelial stem cells (SCs) residing in the SC niche, called labial cervical loop (LaCL). The homeostasis of the SCs is subtly regulated by complex signaling networks. In this study, we focus on retinoic acid (RA), a derivative of Vitamin A and a known pivotal signaling molecule in controlling the functions of stem cells (SCs). We analyzed the expression profiles of several key molecules of the RA signaling pathway in cultured incisor explants upon exogenous RA treatment. The expression patterns of these molecules suggested a negative feedback regulation of RA signaling in the developing incisor. We demonstrated that exogenous RA had negative effects on incisor SCs and that this was accompanied by downregulation of Fgf10, a mesenchymally expressed SC survival factor in the mouse incisor. Supplement of Fgf10 in incisor cultures completely blocked RA effects by antagonizing apoptosis and increasing proliferation in LaCL epithelial SCs. In addition, Fgf10 obviously antagonized RA-induced downregulation of the SC marker Sox2 in incisor epithelial SCs. Our findings suggest that the negative effects of RA on incisor SCs result from inhibition of mesenchymal Fgf10.

[Application of precision-cut liver slice to the study of the effect of glutathione on cadmium chloride hepatotoxicity].

In order to evaluate the feasibility of application of precision cut liver slice(PCLS) to the study of the effect of glutathione on cadmium chloride hepatotoxicity, slices were cultured with CdCl2 and GSH. Slices activity and drug metabolic function was estimated by assay of slice viability, NO secretion, and phase I and phase II enzyme activity. Results showed that the slices activity was significantly inhibited by CdCl2. Various phase I and phase II enzymes activity of slices were obviously reduced by CdCl2, but aniline hydroxidase activity was enhanced. GSH could distinctly reversed the change of slices induced by CdCl2. Therefore, it could be concluded that PCLS culture system was sensitive and steady, and was a good model for pharmacological and toxicological investigation of liver in vitro.

Biphasic effect of citral, a flavoring and scenting agent, on spatial learning and memory in rats.

Although some central effects of citral have been reported, cognitive effects on spatial memory have not been investigated. The evidence showed that citral can regulate the synthesis of retinoic acid (RA), which exerts a vital function in the development and maintenance of spatial memory. In this study, we applied Morris water maze to test the effect of citral on animals' spatial learning and memory. To elucidate the mechanism of this effect, we also measured the retinoic acid concentration in rats' hippocampus by high performance liquid chromatography (HPLC). Our data implied biphasic effects of citral. The low dose (0.1 mg/kg) of citral improved the spatial learning capability, and enhanced the spatial reference memory of rats, whereas the high dose (1.0 mg/kg) was like to produce the opposite effects. Meanwhile, the low dose of citral increased the hippocampal retinoic acid concentration, while the high dose decreased it. Due to the quick elimination and non-bioaccumulation in the body, effects of citral on spatial memory in this study seemed to be indirect actions. The change in hippocampal retinoic acid concentration induced by different doses of citral might be responsible for the biphasic effect of citral on spatial learning and memory.