Engineering Camelina sativa Seeds as a Green Bioreactor for the Production of Affordable Human Pro-insulin that Demonstrates Anti-diabetic Efficacy in Rats

The current production of recombinant insulin via fermenter-based platforms (Escherichia coli and yeast) could not fulfill its fast-growing commercial demands, thus leading to a great interest in its sustainable large-scale production at low cost using a plant-based system. In the present study, Agrobacterium tumefaciens-mediated nuclear stable genetic transformation of an industrial oilseed crop, Camelina sativa, to express pro-insulin (with three furin endoprotease cleavage sites) fused with cholera toxin B subunit (CTB) in their seeds was successfully achieved for the first time. The bar gene was used as a selectable marker for selecting transformants and producing herbicide-resistant camelina plants. The transformation process involved the infiltration of camelina inflorescences (at flower buds with partially opened flowers) with A. tumefaciens and harvesting the seeds (T0) at maturity. The T0 seeds were raised into the putative T1 plants sprayed with Basta herbicide (0.03%, v/v), and the survived green transformed plants tested positive for pro-insulin and bar genes. A transformation frequency of 6.96% was obtained. The integration and copy number of the pro-insulin transgene and its expression at RNA and protein levels were confirmed in T1 plants using Southern hybridization, semi-quantitative Reverse Transcriptase-Polymerase Chain Reaction (sqPCR), and quantitative real-time Time PCR (qPCR) and western blot analysis, respectively. Enzyme-linked immunosorbent Assay (ELISA) quantified the amount of expressed pro-insulin protein, and its anti-diabetic efficacy was validated in diabetic rats on oral feeding. Transgenic plants integrated the pro-insulin gene into their genomes and produced a maximum of 197 µg/100 mg of pro-insulin (0.804% of TSP) that had anti-diabetic efficacy in rats.

Evaluation of cardiac index and right ventricular hypertrophy index in rats under a chronic hypoxic environment at high altitude

High-altitude areas are characterized by low pressure and hypoxia, which have a significant impact on various body systems. This study aimed to investigate the alterations in cardiac index and right ventricular hypertrophy index(RVHI) in rats at different altitudes.Twenty-one male Sprague-Dawley (SD) rats aged 4 weeks were randomly divided into three groups based on altitude. The rats were raised for 28 weeks and then transferred to Qinghai University Plateau Medicine Laboratory. Body weight was measured, heart organs were isolated and weighed, and cardiac index and right ventricular hypertrophy index were determined. Statistical analysis was performed on the data from the three groups. Compared with the plain group, the body weight of the middle-altitude group was significantly decreased (P < 0.05), and cardiac index, RVHI-1, RVHI-2 increased significantly ((P < 0.05). The body weight, whole heart mass, right ventricular mass were significantly decreased in high-altitude group (P < 0.05), RVHI-1 and RVHI-2 were significantly increased (P < 0.05). Compared with the middle-altitude group, the body weight, whole heart mass and right ventricular mass of the high-altitude group were significantly decreased (P < 0.05), and RVHI-1 and RVHI-2 were significantly increased (P < 0.05). Increasing altitude led to a decrease in body weight, whole heart mass, and right ventricular mass in rats, indicating structural changes in the right heart. Additionally, the proportion of right heart to body weight and whole heart increased with altitude.

Taste aversion learning during successive negative contrast

Previous experiments found that acceptance of saccharin by rats was reduced if they had prior experience of sucrose or some other highly palatable solution. This study tested whether such successive negative contrast (SNC) effects involve acquisition of an aversion to the new taste. In three experiments, rats were switched from sucrose exposure in Stage 1 to a less palatable solution containing a new taste in Stage 2. In Experiments 1 and 2, a novel flavor was added to a saccharin solution at the start of Stage 2. In Experiment 1, preference tests revealed a weak aversion to the added vanilla flavor in the Suc-Sacch group, while in Experiment 2 an aversion was found in the Suc-Sacch group to the salty flavor that was used, compared with controls given access either saccharin or water in Stage 1. In Experiment 3, the Suc-Quin group, given quinine solution in Stage 2, displayed a greater aversion to quinine than a Water-Quin control group. These results support the suggestion that taste aversion learning plays a role in the initial suppression of intakes in a qualitative consummatory SNC effect. However, in the light of other evidence, it seems that the unusual persistence of successive negative contrast when rats are switched from sucrose to saccharin is not due to a long-lasting reduction in the value of saccharin.

Transcriptomic analyses of rats exposed to chronic mild stress: Modulation by chronic treatment with the antipsychotic drug lurasidone

Exposure to stressful experiences accounts for almost half of the risk for mental disorders. Hence, stress-induced alterations represent a key target for pharmacological interventions aimed at restoring brain function in affected individuals. We have previously demonstrated that lurasidone, a multi-receptor antipsychotic drug approved for the treatment of schizophrenia and bipolar depression, can normalize the functional and molecular impairments induced by stress exposure, representing a valuable tool for the treatment of stress-induced mental illnesses. However, the mechanisms that may contribute to the therapeutic effects of lurasidone are still poorly understood. Here, we performed a transcriptomic analysis on the prefrontal cortex (PFC) of adult male rats exposed to the chronic mild stress (CMS) paradigm and we investigated the impact of chronic lurasidone treatment on such changes. We found that CMS exposure leads to an anhedonic phenotype associated with a down-regulation of different pathways associated to neuronal guidance and synaptic plasticity within the PFC. Interestingly, a significant part of these alterations (around 25%) were counteracted by lurasidone treatment. In summary, we provided new insights on the transcriptional changes relevant for the therapeutic intervention with lurasidone, which may ultimately promote resilience.

Pioglitazone ameliorates DOX-induced cognitive impairment by mitigating inflammation, oxidative stress, and apoptosis of hippocampal neurons in rats

Doxorubicin (DOX) is broadly used as a medication for cancer treatment. However, DOX has been connected with chemotherapy-related complications, for instance, cognitive impairment (chemobrain). Chemobrain developed in up to 70% of cancer patients; therapeutic is unavailable. This study investigated the preventive effect of pioglitazone (PIO) on neurotoxicity caused by (DOX) in the hippocampus. Forty rats were separated into four groups; control (normal saline 10 ml/kg), DOX (5 mg/kg, intraperitoneally every 3rd day, equivalent to 20 mg/kg cumulative dose), PIO (2 mg/kg in drinking water), and DOX+PIO (DOX, 5 mg/kg, intraperitoneally every 3rd day concurrently PIO, 2 mg/kg in drinking water) and duration of drug treatment lasted for 14 days. The animals were subjected to contextual fear memory tests to characterize the cognitive impairment following DOX treatment. ELISA assessed hippocampal protein expression related to inflammation, oxidative damage, and apoptosis. DOX-treatment produced significant reduction in freezing duration in contextual fear memory tests, which was reversed by PIO co-administration. DOX increased neuroinflammation, oxidative stress, apoptosis, and mitochondrial activity by increasing NF-κB and COX-2 levels, reducing SOD levels, and increasing Bax, caspase-3, and lipid peroxidation. However, DOX did not affect GSH or catalase levels. PIO co-administration reduces NF-κB, COX-2, MDA, Bax, and caspase-3 levels and improves mitochondrial activity and SOD expression. To sum up, DOX therapy accelerates cognitive decline in rats by increasing neuroinflammation, oxidative stress, mitochondrial dysfunction, lipid peroxidation, and apoptosis. PIO is a promising treatment for DOX-induced cognitive impairment.

Pylorus ligation-induced hyperacidity: synergistic prophylactic effects of linagliptin and L-arginine via up-regulation of EP4 receptor subtype and improvement of vascular endothelial damage

Gastric hyperacidity and ulceration are chronic diseases characterized by repeated healing followed by re-exacerbation. The study aims to protect against gastric hyperacidity without interfering with gastric acid secretion. Pylorus ligation-induced hyperacidity is commonly utilized in the induction of gastric ulcers.Forty-two rats were distributed into seven groups (n = 6). Group I comprised sham-operated group. Group II served as pylorus-ligation group. Groups III-VII were given oral Linagliptin (LN; 3 and 6 mg/kg), L-arginine (LA; 150 and 300 mg/kg) and their combination (LN 3 + LA 150 mg/kg), respectively for 7 days. On the 8th day, groups II-VII were subjected to pylorus-ligation.Treatment of pylorus-ligated rats with LN, LA and their combination improved the gastric hyperacidity as exhibited by a marked reduction in the gastric juice volume, total and free acidities and pepsin contents with a noticeable increase in pH. Pre-treatment with LN, LA and their combination showed a marked alleviation in the gastric inflammatory indicators evidenced by reduction in the gastric levels of MCP-1and Il-1β as well as elevation of eNOS levels versus the sham-operated group. A marked up-regulation in the gastric gene expression of PGE, EP4 and VEGF accompanied by an improvement of the histopathologic pictures/scores, and TNF-α and caspase-3 immuno-staining were also recorded.By estimating the combination-index, it can be concluded that combining LN with LA exhibited prophylactic synergistic effects in ameliorating pylorus ligated-induced hyperacidity, mainly via up-regulation of EP4 receptor and improvement of vascular endothelial damage through VEGF expression in gastric mucosa.

Histological changes in pulp-dentin complex in tooth subjected to traumatic occlusion and subluxation

Background

This study evaluated the influence of traumatic occlusion in the dentin-pulp complex a molar teeth submitted to subluxation.

Material and methods

Ninety Wistar rats were divided into groups Naïve (N), Subluxation (S) and Subluxation with traumatic occlusion (STO) and submitted to histological analysis after 7 and 21 days. A quantitative analysis was submitted to one-way ANOVA and Tukey's post-hoc test, and Chi-square and Bonferronís post-hoc test.

Results

S and STO showed a significant increase in blood vessels area (p < 0.0005), amorphous fundamental substance (p < 0.0005) and reactionary dentin formation (p < 0.0005), as well as a decrease in the nuclear profile (p < 0.0005), odontoblast layer (p = 0.013 and p < 0.0005) by day 7 when compared with N. These changes normalized by day 21, except for the reactionary dentin (p < 0.0005) in both S and STO groups. Interestingly, the STO group exhibited significant changes in the increase of pulp calcification (p < 0.0005), presence of tubules with nuclei (p < 0.0005), and inflammatory infiltrate (p < 0.0005), as well reduction of nuclear profile (p < 0.0005), odontoblast layer (p < 0.0005) compared with N and S at day 21.

Conclusions

STO impaired the defence response and decreased pulp regeneration capacity by increasing the inflammatory infiltrate and pulp calcification, and decreasing the nucleated cell number in the odontoblast layer and central pulp.

Effects of social buffering on fear extinction in adolescent rats

Across social species, the presence of another individual can reduce stress reactions to adverse stimuli, a phenomenon known as social buffering. The present study investigated whether social buffering influences the expression and extinction of learned fear in adolescence, a developmental period of diminished fear inhibition and increased social interaction. Quality of maternal care and degree of social investigation were examined as factors that may influence social buffering. In adolescence, male rats were fear conditioned and then given extinction training either in the presence of a same-age rat or alone. Animals were then tested alone for extinction retention. In two experiments, the presence of a conspecific robustly reduced conditioned fear responses during extinction training. Interestingly, a persistent social buffering effect was observed when the extinction and conditioning contexts had prominent differences in features (Experiment 1), but not when these contexts were relatively similar (Experiment 2). Neither quality of maternal care nor degree of social investigation predicted the effects of social buffering. These findings suggest that social buffering robustly dampens fear responses during adolescence when a peer is present and this suppression can persist, in some instances, even when the peer is absent.

Distinct antinociceptive and conditioned behavioral effects are produced by individual cannabinoids and a cannabis-derived mixture

Cannabinoids have been proposed as therapeutics for pain mitigation. Therefore, the antihyperalgesic effects of a proprietary cannabis-derived mixture, Non-Euphoric Phytocannabinoid Elixir #14 (NEPE14), were examined in a persistent Complete Freund's Adjuvant (CFA)-induced model of inflammatory pain. The acute antinociceptive and operant behavioral effects of NEPE14 were then compared with single cannabinoid preparations of Δ9-tetrahydrocannabinol (Δ9-THC), Δ8-THC, the synthetic cannabinoid (-)-CP 55,940 (CP), and cannabidiol (CBD). The THC isomers and CP were also administered with cannabinoid-type-1 receptor (CB1R) antagonist, AM251, and NEPE14 was administered in combination with THC or CP. To induce inflammation, CFA or saline was administered into the paw of male and female Wistar rats. After injections, mechanical hypersensitivity was assessed with Von Frey filaments, and thermal hyperalgesia with a thermal probe. Nine Sprague Dawley rats were also trained to respond under a fixed-ratio 30 schedule for food reinforcers during a 60-min session. Response rates were recorded during the session and warm-water tail-withdrawal latency post session. In CFA-administered rats, mechanical and thermal paw-withdrawal thresholds significantly decreased compared to vehicle, indicating hyperalgesia. Both i.p. (6.6-20.7 ml/kg) and o.m. (30-300 μL) NEPE14 significantly reduced the mechanical and thermal hyperalgesia. In contrast, neither NEPE14 (3.7-20.7 mL/kg i.p., 100-1000 μL o.m.) nor CBD (10-100 mg/kg) significantly decreased response rates or increased tail-withdrawal latency. Acute Δ9-THC, Δ8-THC (1-5.6 mg/kg), and CP (0.032-0.18 mg/kg) significantly and dose-dependently decreased overall response rate and increased tail-withdrawal latency compared to vehicle. AM251 significantly antagonized the rate-decreasing effects of THC, and CP, as well as the antinociceptive effects of CP. Combinations of NEPE14 with Δ9-THC or CP were not significantly different from these cannabinoids alone. In summary, while NEPE14 significantly reduced CFA-induced hyperalgesia, it was more similar to CBD than Δ9-THC, Δ8-THC, and CP for significantly reducing thermal nociception and disrupting conditioned behavior.

Bone marrow stem cell-derived β-cells: New issue for diabetes cell therapy

This investigation aimed to establish the promising role of insulin-producing cells (IPCs) growing from bone marrow-mesenchymal stem cells (BM-MSCs) in relieving hyperglycemia induced in rats. BM-MSCs were differentiated into IPCs using three different protocols. The efficiency of BM-MSCs differentiation into IPCs in vitro was confirmed by detecting IPCs specific gene expression (Foxa-2, PDX-1 and Ngn-3) and insulin release assay. The in vivo study design included 3 groups of male Wistar rats; negative control group, diabetic group and IPCs-transfused group (5 ×106 cells of the most functional IPCs/rat). One month after IPCs infusion, serum glucose, insulin, c-peptide and visfatin levels as well as pancreatic glucagon level were quantified. Gene expression analysis of pancreatic Foxa-2 and Sox-17, IGF-1 and FGF-10 was done. Additionally, histological investigation of pancreatic tissue sections was performed. Our data clarified that, the most functional IPCs are those generated from BM-MSCs using differentiation protocol 3 as indicated by the significant up-regulation of Foxa-2, PDX-1 and Ngn-3 gene expression levels. These findings were further emphasized by releasing of a significant amount of insulin in response to glucose load. The transplantation of the IPCs in diabetic rats elicited significant decline in serum glucose, visfatin and pancreatic glucagon levels along with significant rise in serum insulin and c-peptide levels. Moreover, it triggered significant up-regulation in the expression levels of pancreatic Foxa-2, Sox-17, IGF-1 and FGF-10 genes versus the untreated diabetic counterpart. The histopathological examination of pancreatic tissue almost assisted the biochemical and molecular genetic analyses. These results disclose that the cell therapy holds potential to develop a new cure for DM based on the capability of BM-MSCs to generate β-cell phenotype using specific protocol.

Novel pyridyl-substituted nitronyl nitroxides as potential antiarrhythmic and hypotensive agents with low toxicity and enhanced stability in aqueous solutions

This study explores the antiarrhythmic and hypotensive potential of pyridyl-substituted nitronyl nitroxides derivatives, uncovering the crucial role of a single carbon moiety of the pyridine cycle alongside radical and charged oxygen centers of the imidazoline fragment. Notably, the introduction of fluorine atoms diminished the antiarrhythmic effect, while the most potent derivatives featured the nitronyl nitroxide pattern positioned at the third site of the pyridine cycle. Gender-dependent responses were observed in lead compounds LCF3 and LMe, with LMe inducing temporary bradycardia and hypotension specifically in female rats, and LCF3 causing significant blood pressure reduction followed by rebound in females compared to milder effects in males. Mechanistic insights point towards β1 adrenoceptor blockade as an underlying mechanism, supported by experiments on isolated rat atria. This research underscores the interplay between structure, cardiovascular effects and gender-specific responses, offering insights for therapeutic strategies for treating free radical-associated cardiovascular disorders.

Elevated Level of PINK1/Parkin-Mediated Mitophagy Pathway Involved to the Inhibited Activity of Mitochondrial Superoxide Dismutase in Rat Brains and Primary Hippocampal Neurons Exposed to High Level of Fluoride

To reveal the molecular mechanism of brain damage induced by chronic fluorosis, expression of PTEN-induced kinase 1 (PINK1)/parkin RBR E3 ubiquitin-protein ligase (Parkin)-mediated mitophagy pathway and activity of mitochondrial superoxide dismutase (SOD) were investigated in rat brains and primary cultured neurons exposed to high level of fluoride. Sprague-Dawley (SD) rats were treated with fluoride (0, 5, 50, and 100 ppm) for 3 and 6 months. The primary neurons were exposed to 0.4 mM (7.6 ppm) fluoride and thereafter treated with 100 nM rapamycin (a stimulator of mitophagy) or 50 μM 3-methyladenine (3-MA, an inhibitor of mitophagy) for 24 h. The expressions of PINK1/Parkin at the protein level and the activity of SOD in mitochondria of rat brains and cultured neurons were determined by Western blotting and biochemical method, respectively. The results showed that the rats exposed to fluoride exhibited different degrees of dental fluorosis. In comparison to controls, the expressions of PINK1 and Parkin were significantly higher in the rat brains and primary neurons exposed to high fluoride. In addition, a declined activity of mitochondrial SOD was determined. Interestingly, rapamycin treatment enhanced but 3-MA inhibited the changes of PINK1/Parkin pathway and SOD activity, and the correlations between the inhibited SOD activity and the elevated PINK1/Parkin proteins were observed. The results suggest that the inhibition of mitochondrial SOD activity induced by fluorosis may stimulate the expressions of mitophagy (PINK1/ Parkin) pathway to maintain the mitochondrial homeostasis.

The impact of brivaracetam on cognitive processes and anxiety in various experimental models

BACKGROUND

Memory deficits and anxiety symptoms are undesirable effects that occur in epilepsy patients. They may be associated with the pathophysiology of the disease but also with anticonvulsant therapy. Brivaracetam (BRV) is one of the newest antiseizure drugs. It acts as a ligand for synaptic vesicle glycoprotein 2A (SV2A), which may play a significant role in cognitive processes. Although BRV has a favorable safety profile, its central side effects remain unclear. Hence, this study aimed to evaluate the effect of BRV on various types of memory and anxiety in rats.

METHODS

BRV was given to adult male Wistar rats (n = 80) via gastric tube as a single dose (6 mg/kg or 20 mg/kg) or chronically (6 mg/kg). The effect of the drug on spatial memory was evaluated in the Morris water maze (MWM), fear-learning by passive avoidance (PA), and recognition memory with novel object recognition (NOR). The elevated plus maze (EPM) was used to assess anxiety-like behaviors.

RESULTS

The impact of BRV on memory is dose-dependent and mainly high doses may alter retrieval memory and fear-learning. Sub-chronic administration also impaired retrieval and spatial memory in animals. Moreover, chronic BRV may increase anxiety levels in rats but did not affect recognition memory.

CONCLUSIONS

BRV may cause transient memory deficits as well as anxiety disturbances. However, the results are varied and depend on the type of memory, used dose, and duration of administration.

Ameliorative Effect of Cannabidiol on Topiramate-Induced Memory Loss: The Role of Hippocampal and Prefrontal Cortical NMDA Receptors and CREB/BDNF Signaling Pathways in Rats

Cannabidiol (CBD) is a promising neurological agent with potential beneficial effects on memory and cognitive function. The combination of CBD and topiramate in the treatment of some neurological diseases has been of great interest. Since Topiramate-induced memory loss is a major drawback of its clinical application and the overall effect of the combination of CBD and topiramate on memory is still unclear, here we investigated the effect of CBD on topiramate-induced memory loss and the underlying molecular mechanisms. A one trial step-through inhibitory test was used to evaluate memory consolidation in rats. Moreover, the role of N-methyl-D-aspartate receptors (NMDARs) in the combination of CBD and topiramate in memory consolidation was evaluated through the intra-CA1 administration of MK-801 and NMDA. Western blot analysis was used to evaluate variations in brain-derived neurotrophic factor (BDNF) and phosphorylated cyclic AMP response element-binding protein (pCREB)/CREB ratio in the prefrontal cortex (PFC) and hippocampus (HPC). While the intraperitoneal (i.p.) administration of topiramate (50, 75, and 100 mg/kg) significantly reduced inhibitory time latency, the i.p. administration of CBD (20 and 40 mg/kg) could effectively reverse these effects. Similarly, the sub-effective doses of NMDA plus CBD (10 mg/kg) could improve the topiramate-induced memory loss along with an enhancement in BDNF and pCREB expression in the PFC and HPC. Contrarily, the administration of sub-effective doses of the NMDAR antagonist (MK-801) diminished the protective effects of CBD (20 mg/kg) on topiramate-induced memory loss associated with decreased BDNF and pCREB levels in the PFC and HPC. These findings suggest that CBD can improve topiramate-induced memory impairment, partially by the NMDARs of the PFC and HPC, possibly regulated by the CREB/BDNF signaling pathway.

Effects of Valproic Acid Therapy on Rats with Spinal Cord Injury: A Systematic Review and Meta-Analysis

OBJECTIVE

To systematically evaluate the efficacy of valproic acid (VPA) in rats with spinal cord injury (SCI) to reduce the risk of clinical conversion and provide a valuable reference for future animal and clinical studies.

METHODS

We searched scientific databases, including PubMed, Ovid-Embase, Web of Science, and Scopus databases. The relevant literature was searched from the establishment date of the database to June 28, 2023. The search results were screened, data were extracted, and the quality of the literature was evaluated independently by 2 reviewers.

RESULTS

Among 656 nonduplicated references, 14 articles were included for meta-analysis. The summary results showed that the overall Basso, Beattie and Bresnahan scores of the VPA intervention group were significantly higher than those in the control group at 1-6 weeks after VPA intervention. Subgroup analysis showed that the injury model, administration dose, rat strain, country of study, or follow-up duration had no significant effect on the efficacy of VPA on rats with SCI. In addition, mesh analysis showed that high doses of the VPA group had a better effect on SCI rats, compared with the low dose group and the medium dose group.

CONCLUSIONS

To date, this is the first systematic evaluation of the potential effects of VPA on motor recovery in rats with SCI. We concluded that VPA can promote motor recovery in rats with SCI, and higher doses of VPA seem to be more effective in rats with SCI. However, the limited quality and sample of included studies reduced the application of this meta-analysis. In the future, more high-quality, direct comparative studies are needed to explore this issue in depth.

Adolescent Alcohol Exposure Produces Sex-Specific Long-term Hyperalgesia via Changes in Central Amygdala Circuit Function

BACKGROUND

Exposure to alcohol during adolescence produces many effects that last well into adulthood. Acute alcohol use is analgesic, and people living with pain report drinking alcohol to reduce pain, but chronic alcohol use produces increases in pain sensitivity.

METHODS

We tested the acute and lasting effects of chronic adolescent intermittent ethanol (AIE) exposure on pain-related behavioral and brain changes in male and female rats. We also tested the long-term effects of AIE on synaptic transmission in midbrain (ventrolateral periaqueductal gray [vlPAG])-projecting central amygdala (CeA) neurons using whole-cell electrophysiology. Finally, we used circuit-based approaches (DREADDs [designer receptors exclusively activated by designer drugs]) to test the role of vlPAG-projecting CeA neurons in mediating AIE effects on pain-related outcomes.

RESULTS

AIE produced long-lasting hyperalgesia in male, but not female, rats. Similarly, AIE led to a reduction in synaptic strength of medial CeA cells that project to the vlPAG in male, but not female, rats. Challenge with an acute painful stimulus (i.e., formalin) in adulthood produced expected increases in pain reactivity, and this effect was exaggerated in male rats with a history of AIE. Finally, CeA-vlPAG circuit activation rescued AIE-induced hypersensitivity in male rats.

CONCLUSIONS

Our findings are the first, to our knowledge, to show long-lasting sex-dependent effects of adolescent alcohol exposure on pain-related behaviors and brain circuits in adult animals. This work has implications for understanding the long-term effects of underage alcohol drinking on pain-related behaviors in humans.

Cisplatin Provokes Peripheral Nociception and Neuronal Features of Therapy-Induced Senescence and Calcium Dysregulation in Rats

Therapy-Induced Senescence (TIS) is a form of senescence that is typically described in malignant cells in response to the exposure of cancer chemotherapy or radiation but can also be precipitated in non-malignant cells. TIS has been shown to contribute to the development of several cancer therapy-related adverse effects; however, evidence on its role in mediating chemotherapy-induced neurotoxicity, such as Chemotherapy-induced Peripheral Neuropathy (CIPN), is limited. We here show that cisplatin treatment over two cycles (cumulative dose of 23 mg/kg) provoked mechanical allodynia and thermal hyperalgesia in Sprague-Dawley rats. Isolation of dorsal root ganglia (DRG) from the cisplatin-treated rats demonstrated robust SA-β-gal upregulation at both day 8 (after the first cycle) and day 18 (after the second cycle), decreased lmnb1 expression, increased expression of cdkn1a and cdkn2a, and of several factors of the Senescence-associated Secretory Phenotype (SASP) (Il6, Il1b, and mmp9). Moreover, single-cell calcium imaging of cultured DRGs revealed a significant increase in terms of the magnitude of KCl-evoked calcium responses in cisplatin-treated rats compared to vehicle-treated rats. No significant change was observed in terms of the magnitude of capsaicin-evoked calcium responses in cisplatin-treated rats compared to vehicle-treated rats but with decreased area under the curve of the responses in cisplatin-treated rats. Further evidence to support the contribution of TIS to therapy adverse effects is required but should encourage the use of senescence-modulating agents (senotherapeutics) as novel palliative approaches to mitigate chemotherapy-induced neurotoxicity.

Resveratrol attenuates early life stress induced depression in rats: Behavioural and neurochemical evidence

PURPOSE

Maternal deprivation (MD), a severe naturalistic type of stress in the early postnatal days, is a well-established model of early life stress (ELS) that models juvenile adversity and may result in significant depressive disease in adults. In order to analyze the behavioural, brain monoamine level and HPA axis dysregulations caused by ELS and to determine whether Resveratrol (Res) could counteract these effects, Wistar rat pups were subjected to the MD paradigm, which simulated the consequences of depression.

METHODS

The pups on their postnatal day 1-10 were divided in 5 groups (n = 8); nondeprived (ND), maternally deprived (DC), standard fluoxetine (FLX) (5 mg/kg i.p), Res (20, 40 mg/kg i.p). Excluding the ND group, other pups were separated from dam for 3hr/day from day 1 to 10th day. Treatment was initiated from 50th day and was given for 12 days. The behaviour parameters light/dark test, sucrose preference, and resident intruder test were employed. Serum cortisol levels, brain antioxidant activity, monoamine levels and neuronal morphology in the hippocampus were assessed.

RESULTS

The MD rats showed altered behaviour, including more light-dark transitions, less desire for sucrose, and lower attack latencies. MD influenced the release of serum cortisol and interfered with monoamine, antioxidant levels as well as reduced Nissl bodies in the hippocampus. Treatment with Res led to improved behavioural functions also restored monoamine levels, reduced cortisol release, oxidative stress and prevented histopathological alterations in the rat hippocampus.

CONCLUSION

Res showed neuroprotective effects by improving the brain antioxidants and monoamine levels and HPA axis dysregulation and thus improves MD induced depression like behaviour in Wistar rats.

Tests for learning and memory in rodent regulatory studies

For decades, regulatory guidelines for safety assessment in rodents for drugs, chemicals, pesticides, and food additives with developmental neurotoxic potential have recommended a single test of learning and memory (L&M). In recent years some agencies have requested two such tests. Given the importance of higher cognitive function to health, and the fact that different types of L&M are mediated by different brain regions assessing higher functions represents a step forward in providing better evidence-based protection against adverse brain effects. Given the myriad of tests available for assessing L&M in rodents this leads to the question of which tests best fit regulatory guidelines. To address this question, we begin by describing the central role of two types of L&M essential to all mammalian species and the regions/networks that mediate them. We suggest that the tests recommended possess characteristics that make them well suited to the needs in regulatory safety studies. By brain region, these are (1) the hippocampus and entorhinal cortex for spatial navigation, which assesses explicit L&M for reference and episodic memory and (2) the striatum and related structures for egocentric navigation, which assesses implicit or procedural memory and path integration. Of the tests available, we suggest that in this context, the evidence supports the use of water mazes, specifically, the Morris water maze (MWM) for spatial L&M and the Cincinnati water maze (CWM) for egocentric/procedural L&M. We review the evidentiary basis for these tests, describe their use, and explain procedures that optimize their sensitivity.

The relationship between structural changes in paraspinal muscles and intervertebral disc and facet joint degeneration in the lumbar spine of rats

BACKGROUND

Degenerative spine disease is one of the largest causes of disability worldwide and has a multifactorial aetiology. Determining the leading causes of this multifactorial disease could help create new treatment approaches.

PURPOSE

Study the impact of degenerative changes in the paraspinal muscles caused by local (prolonged compression) or systemic (high-fat diet) factors on the structure of the intervertebral discs (IVDs) and facet joints of the lumbar spine in rats.

METHODS

The study was conducted using two animal models to create degenerative changes in the paraspinal muscles of 10 white laboratory rats for 90 days and five control rats: 1) high-fat diet model (model 1) involved keeping the rats on a high calorie diet; 2) compression model (model 2) involved binding the paraspinal muscles from L2 to S1 using non-absorbable sutures. Histological analysis for the facet joints and IVDs of rats (at the L1-L4 level) with semi-quantitative analysis of the structure conducted used by degeneration grading system for IVDs and cartilage degeneration score (OARSI) for facet joint.

RESULTS

In both models, 90 days after the experiment, the degenerative changes observed in the rats' IVDs were more severe in the annulus fibrosus than in the nucleus pulposus. The height of the IVD in model 1 did not differ from the control group, but in the model 2 was 1.3 times greater (p < 0.001) compared with control. Degenerative changes in the IVD were scored out 5.3 ± 1.7 in model 1 and 5.32 ± 2.1 in model 2 of a possible 16. The height of the articular cartilage of the facet joints was smaller by 1.5 times (p < 0.001) and 1.4 times (p < 0.001) in model 1 and model 2, respectively, compared to the control. Degenerative changes of facet joint were scored out 3.7 ± 0.6 in model 1 and 3.8 ± 0.6 in model 2 of five points according to the cartilage degeneration score.

CONCLUSIONS

It was determined that rats who had structural changes in the lumbar paraspinal muscles as a result of being kept on a high-fat diet or subjected to prolonged compression for 90 days, showed degenerative changes in intervertebral discs and osteoarthritis in facet joints of lumbar spine.

Is bladder outlet obstruction rat model to induce overactive bladder (OAB) has similarity to human OAB? Research on the events in smooth muscle, collagen, interstitial cell and telocyte distribution

BACKGROUND

Cellular and cytoskeletal events of overactive bladder (OAB) have not been sufficiently explored in human bladder due to different limitations. Bladder outlet obstruction (BOO) had been induced in different animal models with different methods to induce (OAB). Similarity of the animal models of BOO to the human OAB is postulated but has not been confirmed. The interstitial cells of Cajal (ICCs), and telocytes (TCs) are an important players in smooth muscles conductivity, they had not been well investigated in the previous BOO models. Objectives are to investigate the morphological pattern of cellular, cytoskeleton and telocytes distribution in BOO rat model and to match the events in two time periods and compare it to the findings in real-world human OAB.

METHODS

Female Sprague-Dawley rats (Rattus norvegicus) were randomly divided into: sham (n = 10), BOO 6 W (n = 10), BOO 8 W (n = 10). Operative procedure to Induce BOO was done under anesthesia with intraperitoneal Ketamine administration. The Effect of induction of BOO was evaluated after 6 and 8 weeks. The rats were anesthetized, and the urinary bladder was removed, while the rat was unconscious under anaesthesia it was transferred to the inhalation anaesthesia cage for euthanasia, rats were sacrificed under light anesthesia using isoflurane. Care of animals, surgical procedure, and euthanasia adhered to Guide for the Care and Use of Laboratory Animals, and AVMA Guidelines for the Euthanasia of Animals. The retrieved bladder was processed for examination with histopathology, immunohistochemistry (IHC), and transmission electron microscopy (EM).

RESULTS

Histological examination of the bladder shows thinner urothelium, condensation of collagen between muscle bundles. IHC with c-kit shows the excess distribution of ICCs between smooth muscle bundles. EM shows frequent distribution of TCs that were situated between collagen fibers. Finings in BOO 6 W group and BOO 8 W group were comparable.

CONCLUSION

The animal model study demonstrated increased collagen/ smooth muscle ratio, high intensity of ICCs and presence of TCs. Findings show that a minimally invasive procedure to induce BOO in rats had resulted in an OAB that has morphological changes that were stable in 6 & 8 weeks. We demonstrated the distribution of TCs and ICCs in the rat animal model and defined them. The population of TCs in the BOO rat model is described for the first time, suggests that the TCs and ICCs may contribute to the pathophysiology of OAB. Similarity of animal model to human events OAB was demonstrated. These findings warrant further study to define the role of TCs in OAB.

CLINICAL TRIAL REGISTRY

The study does not require a clinical trial registration; it is an experimental animal study in basic science and does not include human subjects.

Guided bone regeneration of calcium phosphate-coated and strontium ranelate-doped titanium mesh in a rat calvarial defect model

PURPOSE

When applied alone, titanium (Ti) mesh may not effectively block the penetration of soft tissues, resulting in insufficient new bone formation. This study aimed to confer bioactivity and improve bone regeneration by doping calcium phosphate (CaP) precipitation and strontium (Sr) ranelate onto a TiO2 nanotube (TNT) layer on the surface of a Ti mesh.

METHODS

The TNT layer was obtained by anodizing on the Ti mesh, and CaP was formed by cyclic pre-calcification. The final specimens were produced by doping with Sr ranelate. The surface properties of the modified Ti mesh were investigated using high-resolution field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. To evaluate the effects of surface treatment on cell viability, osteoblasts were cultured for 1-3 days, and their absorbance was subsequently measured. In an in vivo experiment, critical-size defects were created in rat calvaria (Ф=8 mm). After 5 weeks, the rats were sacrificed (n=4 per group) and bone blocks were taken for micro-computed tomography and histological analysis.

RESULTS

After immersing the Sr ranelate-doped Ti mesh in simulated body fluid, the protrusions observed in the initial stage of hydroxyapatite were precipitated as a dense structure. On day 3 of osteoblast culture, cell viability was significantly higher on the pre-calcified Sr ranelate-doped Ti mesh surface than on the untreated Ti mesh surface (P<0.05). In the in vivo experiment, a bony bridge formed between the surrounding basal bone and the new bone under the Sr ranelate-doped Ti mesh implanted in a rat calvarial defect, closing the defect. New bone mineral density (0.91±0.003 g/mm3) and bone volume (29.35±2.082 mm3) significantly increased compared to the other groups (P<0.05).

CONCLUSIONS

Cyclic pre-calcification of a Ti mesh with a uniform TNT layer increased bioactivity, and subsequent doping with Sr ranelate effectively improved bone regeneration in bone defects.

Time-of-flight and black-blood MRI to study intracranial arteries in rats

Intracranial aneurysms (IAs) are usually incidentally discovered by magnetic resonance imaging (MRI). Once discovered, the risk associated with their treatment must be balanced with the risk of an unexpected rupture. Although clinical observations suggest that the detection of contrast agent in the aneurysm wall using a double-inversion recovery black-blood (BB) sequence may point to IA wall instability, the exact meaning of this observation is not understood. Validation of reliable diagnostic markers of IA (in)stability is of utmost importance to deciding whether to treat or not an IA. To longitudinally investigate IA progression and enhance our understanding of this devastating disease, animal models are of great help. The aim of our study was to improve a three-dimensional (3D)-time-of-flight (TOF) sequence and to develop a BB sequence on a standard preclinical 3-T MRI unit to investigate intracranial arterial diseases in rats. We showed that our 3D-TOF sequence allows reliable measurements of intracranial artery diameters, inter-artery distances, and angles between arteries and that our BB sequence enables us to visualize intracranial arteries. We report the first BB-MRI sequence to visualize intracranial arteries in rats using a preclinical 3-T MRI unit. This sequence could be useful for a large community of researchers working on intracranial arterial diseases.Relevance statement We developed a black-blood MRI sequence to study vessel wall enhancement in rats with possible application to understanding IAs instability and finding reliable markers for clinical decision-making.Key points• Reliable markers of aneurysm stability are needed for clinical decision.• Detection of contrast enhancement in the aneurysm wall may be associated with instability.• We developed a black-blood MRI sequence in rats to be used to study vessel wall enhancement of IAs.

Temporal dynamics of BDNF signaling recruitment in the rat prefrontal cortex and hippocampus following a single infusion of a translational dose of ketamine

Despite several decades of investigations, the mechanisms underlying the rapid action of ketamine as antidepressant are still far from being completely understood. Several studies indicated Brain-Derived Neurotrophic Factor (BDNF) as critical for the fast antidepressant action of ketamine, due to its contribution in early and rapid synaptic adaptations. However, previous reports have been essentially based on ketamine dosing modes that differ from the clinical route of administration (slow intravenous infusion). In this report, we investigated the effects of a ketamine dosing mode in male Sprague-Dawley rats showed to be translational to the clinically effective mode in patients. We focused on the first 24 h after infusion to finely dissect potential differences in the contribution of BDNF signaling pathway in prefrontal cortex and hippocampus, two brain regions involved in the antidepressant effects of ketamine. Our data show that the slow ketamine infusion activates the BDNF-mTOR-S6 pathway in prefrontal cortex as early as 2 h and remains on until at least 6 h after the infusion. At the 12 h timepoint, this pathway is turned off in prefrontal cortex while it becomes activated in hippocampus. Interestingly, this pathway appears to be activated in both brain regions at 24 h through a BDNF-independent mechanism adding complexity to the early action of ketamine. We have captured previously unknown dynamics of the early effects of ketamine showing rapid activation/deactivation of BDNF and its downstream signaling in prefrontal cortex and hippocampus, following a precise temporal profile.

Acute and chronic glutamate NMDA antagonist treatment attenuates dopamine D1 antagonist-induced reduction of nicotine self-administration in female rats

Multiple interacting neural systems are involved in sustaining nicotine reinforcement. We and others have shown that dopamine D1 receptors and glutamate NMDA receptors both play important roles in nicotine reinforcement. Blockade of D1 receptors with the antagonist SCH-23390 (0.02 mg/kg) both acutely and chronically significantly decreased nicotine self-administration in rats. Blockade of NMDA receptors (10 mg/kg) acutely with memantine significantly increased nicotine self-administration, but chronic blockade of NMDA receptors with memantine significantly decreased nicotine self-administration. The current study examined the interactions of acute and chronic administration of SCH-23390 and memantine on nicotine self-administration in female rats. Replicating earlier studies, acute and chronic SCH-23390 significantly decreased nicotine self-administration and memantine had a biphasic effect with acute administration increasing nicotine self-administration and chronic memantine showed a non-significant trend toward decreasing it. However, chronic interaction study showed that memantine significantly attenuated the decrease in nicotine self-administration caused by chronic SCH-23390. These studies provide important information that memantine attenuates the efficacy of D1 antagonist SCH 23390 in reducing nicotine-self-administration. These two drugs do not appear to have mutually potentiating effects to aid tobacco cessation.