Evans Rat Research Articles

Effect of acute and chronic ethanol on atrial fibrillation vulnerability in rats

Even though ethanol consumption has been associated with risk of atrial fibrillation (AF), little is known about how ethanol affects atrial electrophysiology. The purpose of this study was to study the electrophysiological effect of ethanol on rat AF. Atrial optical mapping was performed on male Long Evans rat hearts with escalating concentrations of ethanol (0, 1, 2, and 3 mM). In addition, patch-clamp recordings on isolated atrial myocytes were performed. In chronic ethanol study, rats were divided into control and chronic ethanol groups (20% ethanol in drinking water for 6 months). Atrial optical mapping, histology, immunohistochemistry, and reverse transcriptase polymerase chain reaction were performed in chronic rats. Acute ethanol perfusion increased AF vulnerability (0% at 0 mM, 0% at 1 mM, 57.1% at 2 mM, and 100% at 3 mM) in a dose-related response. Ethanol infusion decreased conduction velocities (CVs) in both atria and shortened effective refractory periods (ERP) only in the right atria with increased in dispersion of refractoriness. Action potential duration at 50% and 90% repolarization from right atrial myocytes were shortened, with corresponding increase of sustained potassium current. Chronic ethanol consumption increased AF inducibility (10% control vs 95.2% chronic ethanol). CVs in both atria were significantly decreased. ERP of the right atrium was shortened, and dispersion of ERP was increased. Expression (mRNA) of KCNQ1 and connexin40 were increased, but KCNA5 was decreased in the right atrium of rats exposed to chronic ethanol. Acute and chronic exposure to ethanol increases AF vulnerability by slowing CV, shortening right atrial ERP, and increasing dispersion of ERP.

Alcohol's Dysregulation of Maternal-Fetal IL-6 and p-STAT3 Is a Function of Maternal Iron Status.

Prenatal alcohol exposure (PAE) causes long-term growth and neurodevelopmental deficits that are worsened by maternal iron deficiency (ID). In our preclinical rat model, PAE causes fetal anemia, brain ID, and elevated hepatic iron via increased maternal and fetal hepcidin synthesis. These changes are normalized by a prenatal iron-fortified (IF) diet. Here, we hypothesize that iron status and PAE dysregulate the major upstream pathways that govern hepcidin production-EPO/BMP6/SMAD and IL-6/JAK2/STAT3. Pregnant, Long Evans rat dams consumed ID (2 to 6ppm iron), iron-sufficient (IS, 100ppm iron), or IF (500ppm iron) diets and received alcohol (5g/kg) or isocaloric maltodextrin daily from gestational days (GD) 13.5 to 19.5. Protein and gene expression were quantified in the 6 experimental groups at GD 20.5. PAE did not affect Epo or Bmp6 expression, but reduced p-SMAD1/5/8/SMAD1/5/8 protein ratios in both IS and ID maternal and fetal liver (all p's<0.01). In contrast, PAE stimulated maternal hepatic expression of Il-6 (p=0.03) and elevated p-STAT3/STAT3 protein ratios in both IS and ID maternal and fetal liver (all p's<0.02). PAE modestly elevated maternal Il-1β, Tnf-α, and Ifn-γ. Fetal cytokine responses to PAE were muted compared with dams, and PAE did not affect hepatic Il-6 (p=0.78) in IS and ID fetuses. Dietary iron fortification sharply attenuated Il-6 expression in response to PAE, with IF driving a 150-fold decrease (p<0.001) in maternal liver and a 10-fold decrease (p<0.01) in fetal liver. The IF diet also normalized p-STAT3/STAT3 ratios in both maternal and fetal liver. These findings suggest that alcohol-driven stimulation of the IL-6/JAK2/STAT3 pathway mediates the elevated hepcidin observed in the PAE dam and fetus. Normalization of these signals by IF suggests that dysregulated hepcidin is driven by alcohol's disruption of the IL-6/JAK2/STAT3 pathway. Prenatal dietary IF represents a potential therapeutic approach for PAE that warrants further investigation.

Maternal Preconception Stress Alters Prefrontal Cortex Development in Long–Evans Rat Pups without Changing Maternal Care

Stress during development can shift the typical developmental trajectory. Maternal stress prior to conception has recently been shown to exert similar influences on the offspring. The present study questioned if a consistent maternal stressor prior to conception (elevated platform stress) would impact the pre-weaning development of offspring brain and behavior, and if maternal care was vulnerable to this experience. Adult female Long–Evans rats were subjected to elevated platform stress for 27 days prior to mating with non-stressed males. Maternal care was monitored, and pups were assessed in two tests of early behavioral development, negative geotaxis and open field. Pups were perfused at weaning and their brains were extracted and stained with Cresyl Violet, allowing gross measurements of cortical and subcortical structures and estimates of neuron density. Main findings indicate that a change in prefrontal cortical thickness is evident despite no change in maternal care. Female offspring show a decrease in medial-dorsal thalamus size. The current study failed to find an effect of maternal preconception stress on early behavioral development. These results suggest that the PFC, and likely behavior dependent on the PFC, is vulnerable to maternal preconception stress and that a strong sex effect is evident. Further studies should examine how such offspring fare using a lifespan model and investigate potential mechanisms responsible for these effects.

Ipsilesional Motor Cortex Plasticity Participates in Spontaneous Hindlimb Recovery after Lateral Hemisection of the Thoracic Spinal Cord in the Rat.

After an incomplete spinal cord injury (SCI) spontaneous motor recovery can occur in mammals, but the underlying neural substrates remain poorly understood. The motor cortex is crucial for skilled motor learning and the voluntary control of movement and is known to reorganize after cortical injury to promote recovery. Motor cortex plasticity has also been shown to parallel the recovery of forelimb function after cervical SCI, but whether cortical plasticity participates in hindlimb recovery after SCI remains unresolved. Using intracortical microstimulation (ICMS) mapping, behavioral and cortical inactivation techniques in the female Long-Evans rat, we evaluated the spontaneous cortical mechanisms of hindlimb motor recovery 1-5 weeks after lateral hemisection of the thoracic (T8) spinal cord that ablated the crossed corticospinal tract (CST) from the contralesional motor cortex while sparing the majority of the CST from the ipsilesional motor cortex. Hemisection initially impaired hindlimb motor function bilaterally but significant recovery occurred during the first 3 weeks. ICMS revealed time-dependent changes in motor cortex organization, characterized by a chronic abolishment of hindlimb motor representation in the contralesional motor cortex and the development of transient bilateral hindlimb representation in the ipsilesional motor cortex 3 weeks after hemisection, when significant behavioral recovery occurred. Consistently, reversible inactivation of the ipsilesional, but not the contralesional motor cortex, during skilled ladder walking 3 weeks after hemisection reinstated deficits in both hindlimbs. These findings indicate that the ipsilesional motor cortex transiently reorganizes after lateral hemisection of the thoracic spinal cord to support recovery of hindlimb motor function.SIGNIFICANCE STATEMENT Partial motor recovery can occur after an incomplete spinal cord injury and is hypothesized to result from the reorganization of spared descending motor pathways. The motor cortex is crucial for the control of voluntary movement and contains topographical movement representations (motor maps) that are highly plastic. We examined the organization of hindlimb motor maps bilaterally after a lateral hemisection of the spinal cord to show that while motor maps are abolished in the deefferented cortex, the spared ipsilesional cortex transiently reorganizes to gain a representation of the affected hindlimb after injury that relates to recovery. This finding demonstrates that plasticity in the ipsilesional motor cortex at early time points after spinal cord hemisection is initially important to support motor recovery.

Pharmacological and Toxicological Threshold of Bisammonium Tetrakis 4-(N,N-Dimethylamino)pyridinium Decavanadate in a Rat Model of Metabolic Syndrome and Insulin Resistance.

Vanadium(IV/V) compounds have been studied as possible metallopharmaceutical drugs against diabetes mellitus. However, mechanisms of action and toxicological threshold have been tackled poorly so far. In this paper, our purposes were to evaluate the metabolic activity on dyslipidemia and dysglycemia, insulin signaling in liver and adipose tissue, and toxicology of the title compound. To do so, the previously reported bisammonium tetrakis 4-(N,N-dimethylamino)pyridinium decavanadate, the formula of which is [DMAPH]4(NH4)2[V10O28]·8H2O (where DMAPH is 4-dimethylaminopyridinium ion), was synthesized, and its dose-response curve on hyperglycemic rats was evaluated. A Long–Evans rat model showing dyslipidemia and dysglycemia with parameters that reproduce metabolic syndrome and severe insulin resistance was generated. Two different dosages, 5 µmol and 10 µmol twice a week of the title compound (equivalent to 2.43 mg·V/kg/day and 4.86 mg·V/kg/day, resp.), were administered intraperitoneal (i.p.) for two months. Then, an improvement on each of the following parameters was observed at a 5 µmol dose: weight reduction, abdominal perimeter, fatty index, body mass index, oral glucose tolerance test, lipid profile, and adipokine and insulin resistance indexes. Nevertheless, when the toxicological profile was evaluated at a 10 µmol dose, it did not show complete improvement, tested by the liver and adipose histology, as well as by insulin receptor phosphorylation and GLUT-4 expression. In conclusion, the title compound administration produces regulation on lipids and carbohydrates, regardless of dose, but the pharmacological and toxicological threshold for cell regulation are suggested to be up to 5 µmol (2.43 mg·V/kg/day) dose twice per week.

Maternal care-related differences in males and females rats' sensitivity to ethanol and the associations between the GABAergic system and steroids in males.

This study investigated the effect of maternal care on adolescent ethanol consumption, sensitivity to ethanol-induced hypnosis, as well as gonadal hormones and γ-aminobutyric acid type-A (GABAA ) systems. Long Evans rat dams were categorized by maternal licking/grooming (LG) frequency into High- and Low-LG mothers. Both female and male offspring from Low-LG rats demonstrated a greater sensitivity to ethanol-induced hypnosis in the loss-of-righting-reflex test at ethanol doses of 3.0 and 3.5 g/kg during late-adolescence (postnatal Day 50) but not at mid-adolescence (postnatal Day 42). However, we found no effect of maternal care on consumption of a 5% ethanol solution in a two-bottle choice test. We further investigated the association between the observed variations in sensitivity to ethanol-induced hypnosis and baseline hormonal levels in males. In male offspring from Low-LG mothers compared to High-LG mothers, baseline plasma corticosterone and progesterone levels were higher. GABAA α1 and δ subunit expressions were also higher in the cerebral cortex of Low-LG males but lower in the cerebellar synaptosomal fraction. Early environmental influences on adolescent sensitivity to ethanol-induced hypnosis, consumption, and preference may be mediated by gonadal hormones and possibly through GABAergic functions.

Evaluation and Optimization of Effective-dose of Alloxan for Inducing Type-2 Diabetes Mellitus in Long Evans Rat

Evaluation and Optimization of Effective-dose of Alloxan for Inducing Type-2 Diabetes Mellitus in Long Evans Rat

A general protocol of ultra-high resolution MR angiography to image the cerebro-vasculature in 6 different rats strains at high field

BackgroundDifferences in the cerebro-vasculature among strains as well as individual animals might explain variability in animal models and thus, a non-invasive method tailored to image cerebral vessel of interest with high signal to noise ratio is required. New methodExperimentally, we describe a new general protocol of three-dimensional time-of-flight magnetic resonance angiography to visualize non-invasively the cerebral vasculature in 6 different rat strains. Flow compensated angiograms of Sprague Dawley, Wistar Kyoto, Lister Hooded, Long Evans, Fisher 344 and Spontaneous Hypertensive Rat strains were obtained without the use of contrast agents. At 11.7T using a repetition time of 60ms, an isotropic resolution of up to 62μm was achieved; total imaging time was 98min for a 3D data set. ResultsThe visualization of the cerebral arteries was improved by removing extra-cranial vessels prior to the calculation of maximum intensity projection to obtain the angiograms. Ultimately, we demonstrate that the newly implemented method is also suitable to obtain angiograms following middle cerebral artery occlusion, despite the presence of intense vasogenic edema 24h after reperfusion. Comparison with existing methodsThe careful selection of the excitation profile and repetition time at a higher static magnetic field allowed an increase in spatial resolution to reliably detect of the hypothalamic artery, the anterior choroidal artery as well as arterial branches of the peri-amygdoidal complex and the optical nerve in six different rat strains. ConclusionsMR angiography without contrast agent can be utilized to study cerebro-vascular abnormalities in various animal models.

Long Evans rat spermatogonial lines are effective germline vectors for transgenic rat production.

Long Evans rat strains are applied as research models in a broad spectrum of biomedical fields (>15,800 citations, NCBI PubMed). Here, we report an approach to genetically modify the Long Evans rat germline in donor spermatogonial stem cells. Long Evans rat spermatogonial lines were derived from freshly isolated laminin-binding spermatogonia. Laminin-binding spermatogonia were cultured over multiple passages on fibroblast feeder layers in serum-free culture medium containing GDNF and FGF2. Long Evans rat spermatogonial lines were genetically modified by transposon transduction to express a germline, tdTomato reporter gene. Donor rat spermatogonial lines robustly regenerated spermatogenesis after transplantation into testes of busulfan-treated, allogenic, Long Evans rats. Donor-derived spermatogenesis largely restored testis size in the chemically sterilized, recipient Long Evans rats. Recipient Long Evans rats stably transmitted the tdTomato germline marker to subsequent generations. Overall, Long Evans rat spermatogonial lines provided effective donor germline vectors for genetically modifying Long Evans rats.

Microdialysis of norepinephrine in prefrontal cortex and ventral striatum and effects of ethanol in the Long Evans rat

Microdialysis of norepinephrine in prefrontal cortex and ventral striatum and effects of ethanol in the Long Evans rat

Audiogenic seizure activity following HSV-1 GAD65 sense or antisense injection into inferior colliculus of Long-Evans rat.

Herpes virus technology involving manipulation of GAD65 was used to study effects on audiogenic seizures (AGS). Audiogenic seizure behaviors were examined following injections of replication-defective herpes simplex virus (HSV-1) vectors incorporating sense or antisense toward GAD65 along with 10% lac-Z into the central nucleus of inferior colliculus (CNIC) of Long-Evans rats. In seizure-sensitive animals developmentally primed by intense sound exposure, injection of GAD65 in the sense orientation increased wild running latencies and reduced incidence of clonus compared with lac-Z only, unoperated, and vehicle seizure groups. In contrast, infection of CNIC with GAD65 antisense virus resulted in 100% incidence of wild running and clonus behaviors in AGS animals. Unprimed animals not operated continued to show uniform absence of seizure activity. Administration of GAD65 antisense virus into CNIC produced novel wild running and clonus behaviors in some unprimed animals. Staining for β-galactosidase in all vector animals revealed no differences in pattern or numbers of immunoreactive cells at injection sites. Qualitatively, typical small and medium multipolar/stellate and medium fusiform neurons appeared in the CNIC of vector animals. These results demonstrate that HSV-1 vector constructs implanted into the CNIC can predictably influence incidence and severity of AGS and suggest that viral vectors can be useful in studying GABA mechanisms with potential for therapeutic application in epilepsy. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Potential Contributions of the Tobacco Nicotine-Derived Nitrosamine Ketone to White Matter Molecular Pathology in Fetal Alcohol Spectrum Disorder.

Fetal alcohol spectrum disorder (FASD) is associated with long-term deficits in cognitive and motor functions. Previous studies linked neurodevelopmental abnormalities to increased oxidative stress and white matter hypotrophy. However, similar effects occur with low-dose nitrosamine exposures, alcohol abuse correlates with cigarette smoking, and tobacco smoke contains tobacco-specific nitrosamines, including NNK. Tobacco smoke exposure is a co-factor in FASD. Long Evans rat pups were i.p. administered ethanol (2 g/kg) on postnatal days (P) 2, 4, 6 and/or NNK (2 mg/kg) on P3, P5, and P7 to simulate third trimester human exposures. Oligodendroglial myelin-associated, neuroglial, and relevant transcription factor mRNA transcripts were measured using targeted PCR arrays. Ethanol and NNK differentially altered the expression of immature and mature oligodendroglial, neuronal and astrocytic structural and plasticity-associated, and various transcription factor genes. NNK's effects were broader and more pronounced than ethanol's, and additive or synergistic effects of dual exposures impacted expression of all four categories of genes investigated. Developmental exposures to alcohol and NNK (via tobacco smoke) contribute to sustained abnormalities in brain white matter structure and function via distinct but overlapping alterations in the expression of genes that regulate oligodendrocyte survival, maturation and function, neuroglial structural integrity, and synaptic plasticity. The results support the hypothesis that smoking may contribute to brain abnormalities associated with FASD.

The strain of an accompanying conspecific affects the efficacy of social buffering in male rats

Social buffering is a phenomenon in which stress in an animal is ameliorated when the subject is accompanied by a conspecific animal(s) during exposure to distressing stimuli. We previously reported that in male Wistar rats, the presence of another Wistar rat mitigates conditioned fear responses to an auditory conditioned stimulus (CS). Subsequent analyses revealed several characteristics of this social buffering of conditioned fear responses. However, information regarding the specificity of accompanying conspecifics is still limited. In the present study, we assessed whether rats of other strains could induce social buffering in Wistar rats. When a fear-conditioned Wistar subject was re-exposed to the CS alone, we observed increased freezing and decreased investigation and walking, as well as elevated corticosterone levels. The presence of a Wistar, Sprague–Dawley, or Long–Evans rat blocked these responses, suggesting that social buffering was induced by these strains of rats. In contrast, a Fischer 344 rat did not induce social buffering in the Wistar subject. We further found that an inbred Lewis rat induced social buffering whereas a Brown Norway rat, a strain that has been established independently from Wistar rats, did not. These results suggest that the difference in origin, rather than the inbred or outbred status of the associate rat, seemed to account for the lack of social buffering induced by the F344 rats. Based on these findings, we conclude that strains of an accompanying conspecific can affect the efficacy of social buffering in rats.

Improvements and additions to the Multiple Path Particle Dosimetry model

A little over a decade ago, the first UC Irvine dosimetry conference was held entitled “Frontiers in Aerosol Dosimetry Research”. At that time, mechanistic dosimetry models, such as the multiple path particle dosimetry (MPPD) model, primarily focused on humans, with a model for the Long Evans rat also being available. In the intervening years, advances have occurred on a number of fronts that have led to improvements and additions to the user-friendly MPPD software program that is available free to the public. Here, we review a number of the expanded capabilities of the MPPD model. These include:•Calculating deposition and clearance simultaneously for up to 4 lognormal distributions having different mass median aerodynamic diameters and geometric standard deviations. This feature is useful whenever the exposure atmosphere is multimodal as is often the case with workplace exposure atmospheres and can occur in inhalation toxicology studies if the particulate aerosol is difficult to generate stably.•The ability to adjust the total aerosol deposition for the amount of particle “X” when “X” is a subset of the total aerosol. This is particularly important for workplace exposures where the particles of interest (e.g., copper containing particles) are part of the total dust aerosol that was measured.•The ability to specify clearance rates and mucous velocities for both animals and humans so any type of particle can be modeled as well as various lung disease states.•The addition of dose metrics for the upper respiratory tract and enhancements to dose metrics for the lower respiratory tract.•Addition of a lung geometry/morphometry model and physiologic input variables for mice (Balb/c and B6C3F1), Sprague-Dawley rats, male rhesus monkeys, sheep, and pigs. The deposition and clearance of particles in these species can now be examined.

Potential Co-Factor Role of Tobacco Specific Nitrosamine Exposures in the Pathogenesis of Fetal Alcohol Spectrum Disorder.

BackgroundCerebellar developmental abnormalities in Fetal Alcohol Spectrum Disorder (FASD) are linked to impairments in insulin signaling. However, co-morbid alcohol and tobacco abuses during pregnancy are common. Since smoking leads to tobacco specific Nitrosamine (NNK) exposures which have been shown to cause brain insulin resistance, we hypothesized that neurodevelopmental abnormalities in FASD could be mediated by ethanol and/or NNK.MethodsLong Evans rat pups were intraperitoneal (IP) administered ethanol (2 g/kg) on postnatal days (P) 2, 4, 6 and/or NNK (2 mg/kg) on P3, P5, and P7 to simulate third trimester human exposures. The Cerebellar function, histology, insulin and Insulin-like Growth Factor (IGF) signaling, and neuroglial protein expression were assessed.ResultsEthanol, NNK and ethanol+NNK groups had significant impairments in motor function (rotarod tests), abnormalities in cerebellar structure (Purkinje cell loss, simplification and irregularity of folia, and altered white matter), signaling through the insulin and IGF-1 receptors, IRS-1, Akt and GSK-3β, and reduced expression of several important neuroglial proteins. Despite similar functional effects, the mechanisms and severity of NNK and ethanol+NNK induced alterations in cerebellar protein expression differed from those of ethanol.ConclusionsEthanol and NNK exert independent but overlapping adverse effects on cerebellar development, function, insulin signaling through cell survival, plasticity, metabolic pathways, and neuroglial protein expression. The results support the hypothesis that tobacco smoke exposure can serve as a co-factor mediating long-term effects on brain structure and function in FASD.

A Novel Approach to Identify Photoreceptor Compartment-Specific Tulp1 Binding Partners.

Photoreceptors (PRs) are highly polarized and compartmentalized cells with large amounts of proteins synthesized in the inner segment (IS) and transported to the outer segment (OS) and synaptic terminal. The PR-specific protein, Tulp1, is localized to the IS and synapse and is hypothesized to be involved in protein trafficking. To better understand the molecular processes that regulate protein trafficking in PRs, we aimed to identify compartment-specific Tulp1 binding partners. Serial tangential sectioning of Long Evans rat retinas was utilized to isolate the IS and synaptic PR compartments. Tulp1 binding partners in each of these layers were identified using co-immunoprecipitation (co-IP) with Tulp1 antibodies. The co-IP eluates were separated by SDS-PAGE, trypsinized into peptide fragments, and proteins were identified by liquid chromatography tandem mass spectrometry. In the IS, potential Tulp1-binding partners included cytoskeletal scaffold proteins, protein trafficking molecules, as well as members of the phototransduction cascade. In the synaptic region, the majority of interacting proteins identified were cytoskeletal. A separate subset of proteins were identified in both the IS and synapse including chaperones and family members of the GTPase activating proteins. Tulp1 has two distinct PR compartment-specific interactomes. Our results support the hypothesis that Tulp1 is involved in the trafficking of proteins from the IS to the OS and the continuous membrane remodeling and vesicle cycling at the synaptic terminal.

Retinal ganglion cell neuroprotection induced by activation of alpha7 nicotinic acetylcholine receptors

The α7nAChR agonist, PNU-282987, has previously been shown to have a neuroprotective effect against loss of retinal ganglion cells (RGCs) in an in vivo glaucoma model when the agent was injected into the vitreous chamber of adult Long Evans rat eyes. Here, we characterized the neuroprotective effect of PNU-282987 at the nerve fiber and retinal ganglion cell layer, determined that neuroprotection occurred when the agonist was applied as eye drops and verified detection of the agonist in the retina, using LC/MS/MS.To induce glaucoma-like conditions in adult Long Evans rats, hypertonic saline was injected into the episcleral veins to induce scar tissue and increase intraocular pressure. Within one month, this procedure produced significant loss of RGCs compared to untreated conditions. RGCs were quantified after immunostaining with an antibody against Thy 1.1 and imaged using a confocal microscope. In dose–response studies, concentrations of PNU-282987 were applied to the animal's right eye two times each day, while the left eye acted as an internal control. Eye drops of PNU-282987 resulted in neuroprotection against RGC loss in a dose-dependent manner using concentrations between 100 μM and 2 mM PNU-282987. LC/MS/MS results demonstrated that PNU-282987 was detected in the retina when applied as eye drops, relatively small amounts of PNU-282987 were measured in blood plasma and no PNU-282987 was detected in cardiac tissue. These results support the hypothesis that eye drop application of PNU-282987 can prevent loss of RGCs associated with glaucoma, which can lead to neuroprotective treatments for diseases that involve α7nAChRs.

Anti-inflammatory and Antioxidant Activities of Cucumis sativus Leaves

This study was carried out to evaluate the anti-inflammatory and antioxidant activities of Cucumis sativus Linn. (Family: Cucurbitaceae) leaves. The methanolic extract of C. sativus leaves (MCS) was investigated for antiinflammatory activities in Long Evans rat model at two different doses of 150 and 250 mg/kg body weight and the effects were compared with the standard, indomethacin (10 mg/kg body weight). It exhibited highest antiinflammatory activity at the dose 250 mg/kg. In the formalin test, the extract at both doses (150 and 250 mg/kg body weight) significantly prevented the increase in volume of paw edema (P&lt;0.05 and P&lt;0.001). In carrageenan-induced paw edema test the MCS significantly (P?0.001) reduced inflammation by 57.35 % (150 mg/kg body weight) and 72.06% (250 mg/kg body weight) in comparison to the standard drug, indomethacin (79.41%) at the end of 5h. MCS was also screened for DPPH scavenging activity, total antioxidant capacity, reducing ability as well as total phenolics content to assess its antioxidant potential. Total phenolic content and total antioxidant capacity of MCS were found to be 262.31 mg/g equivalent of gallic acid and 267.2 mg/g equivalent of ascorbic acid, respectively. The IC50 of free radical scavenging of DPPH was 13.06 ?g/ml while that of standard ascorbic acid was 13.17 ?g/ml. The reducing power of MCS was found to be concentration dependent.Bangladesh Pharmaceutical Journal 18(2): 169-173, 2015

RU486 facilitates or disrupts the sensitization of sexual behaviors by estradiol in the ovariectomized Long–Evans rat: Effect of timecourse

An acute injection of estradiol benzoate (EB) to the ovariectomized (OVX) rat activates low levels of lordosis, and subsequent progesterone (P) administration augments lordosis and recruits a complete pattern of sexual behavior including appetitive behaviors (e.g., hops/darts and solicitations). However, repeated injections of 5μg or 10μg EB (but not 2μg EB), administered every 4days to sexually-experienced OVX rats results in a behavioral sensitization, such that lordosis quotients (LQs) and appetitive behaviors progressively increase. We have shown that adrenal P does not play a critical role because behavioral sensitization to EB is not prevented by adrenalectomy. Here we tested whether P receptors play a role by examining the effect of chronic administration of the P receptor antagonist RU486 at a dose that reliably inhibits sexual behavior in fully primed OVX rats. Females were treated with EB (5 or 10μg), and 5mg RU486 dissolved in 0.4mL vehicle (VEH; 80% sesame oil, 15% benzyl benzoate, 5% benzyl alcohol) 48h and 5h prior to each of 7 tests, respectively, occurring at 4-day intervals in unilevel 4-hole pacing chambers. Control animals were treated with 2, 5, or 10μg EB+VEH. As expected, sensitization did not occur in females treated with 2μg EB+VEH, and those females received fewer intromissions and ejaculations than all other groups. RU486 did not prevent the sensitization of LQ, moderate and high lordosis magnitudes (LM2 and LM3) or appetitive sexual behaviors on early tests, and in fact potentiated appetitive behaviors, LQ, LM2 and LM3, consistent with its facilitative actions in females treated with EB-alone, as we and others have reported previously. However, despite the initial facilitation, blocking P receptors by chronic administration of RU486 inhibited the maintenance of behavioral sensitization to EB.

The inhibitory effects of corncob bedding on sexual behavior in the ovariectomized Long–Evans rat treated with estradiol benzoate are overcome by male cues

The mechanisms underlying the sensitization of sexual behaviors by repeated administration of estradiol benzoate (EB) to ovariectomized (OVX) rats are not well understood. Here we tested whether two housing conditions play a role. Sexual behavior in the female rat is dependent on the activation of ERα (estrogen receptor alpha) by estradiol. Corncob (CC) bedding has been reported to have adverse effects on the reproductive behavior and physiology of rats, and to disrupt ERα signaling in mice. In addition, some rodent behaviors are stimulated by olfactory stimuli and enhanced in the presence of estradiol. Upon arrival to the facilities OVX Long–Evans rats were housed on either Sani-Chips (SC) or CC in a room that housed only females (F) or males and females (M). Females were first given four sexual training sessions with 10μg EB+500μg progesterone (P; administered 48h and 4h prior to training, respectively), followed by a 2-week hormone washout period. Next, 10μg EB was administered s.c. every 4days, 48h prior to each of 8 test sessions in a unilevel 4-hole pacing chamber. On the final training day (i.e., when primed with EB+P), no inhibitory effects of corncob bedding were found, however a facilitation of the lordosis quality occurred in SC/F. Although all groups appear to have sensitized to the repeated administration of EB, CC/F animals displayed fewer high quality lordosis magnitudes and hop/darts, and received fewer mounts and intromissions overall. They also had a lower lordosis quotient (LQ) on tests 2–4 although this effect disappeared by test 5. These results suggest that although CC may inhibit some components of female sexual behavior when primed with EB alone, cues from sexually vigorous males can overcome that inhibition. Moreover, they suggest that male cues can facilitate mechanisms of estradiol sensitization. We recommend that quality control studies be conducted at individual institutions to assess any impact of corncob bedding on animal physiology and behavior.