Kindled Rats Research Articles

ERK activation is required for the antiepileptogenic effect of low frequency electrical stimulation in kindled rats

IntroductionThe signaling pathways involved in the antiepileptogenic effect of low frequency electrical stimulation (LFS) have not been fully understood. In the present study the role of extracellular signal-regulated kinase (ERK) signaling cascade was investigated in mediating the inhibitory effects of LFS on kindled seizures. MethodsAnimals received kindling stimulations for seven days (the mean number of stimulation days for achieving stage 5 seizure) according to semi-rapid perforant path kindling protocol (12 stimulations per day at 10 min intervals). LFS (0.1 ms pulse duration at 1 Hz, 800 pulses) was applied at 5 min after the last kindling stimulation every day. During the kindling procedure, FR180204 (inhibitor of ERK) was daily microinjected (1 μg/μl; intracerebroventricular) immediately after the last kindling stimulation and before LFS application. The expression of activated ERK (p-ERK) in the dentate gyrus was also investigated using immunohistochemistry technique. ResultsApplication of LFS at 5 min after the last kindling stimulation had inhibitory effect on kindling rate. FR180204 had no significant effect on seizure parameters when administered at the dose of 1 μg/μl in kindled group of animals. However, microinjection of FR180204 before LFS application reduced the inhibitory effect of LFS on seizure severity and field potential parameters (i.e. the slope of population field excitatory postsynaptic potentials and population spike amplitude) during kindling. FR180204 also blocked the preventing effects of LFS on kindling-induced increase in early (at 10–40 ms intervals) and late (at 300–1000 ms intervals) paired pulse depression. In addition, application of LFS following kindling stimulations increased the expression of p-ERK in the dentate gyrus. ConclusionObtained results showed ERK signaling pathway had important role in mediating the antiepileptogenic effect of LFS in perforant path kindling. These findings represent a promising opportunity to gain insight about LFS mechanism in epilepsy therapy.

Safranal carried by nanostructured lipid vehicles inhibits generalized epilepsy in mice.

Safranal, a main component of Crocus sativus, is suggested to have neuroprotective effects. The aim of this study was to investigate the effect of safranal and nanostructured lipid vehicle (NLV) carried safranal in acute and chronic experimental mice models of epilepsy. In PILO acute seizure model, safranal dose-dependently extended latency to generalized seizure, decreased the highest seizure stages and the number of generalized seizures. Moreover, NLV carried safranal further enhanced the anti-seizure effect, which is comparable to the action of sodium valproate. Meanwhile, NLV carried safranal reduced and delayed the electroencephalogram spectra power after pilocarpine injection. In histological aspect, safranal dose-dependently reduced the loss of neurons induced by seizure and NLV system further improved this protection at the same dose. In MES acute model, safranal markedly increased the electroconvulsive threshold, where NLV further improved its effect. In PTZ chronic seizure model, NLV carried safranal significantly delayed the kindling rate of progress and the time it took to reach generalized seizures as compared to NLV control group. In conclusion, this study indicates that safranal inhibits generalized seizure in acute and chronic epilepsy models in mice and NLV can enhance this effect. So, NLV carried safranal may have potential value in treatment of generalized epilepsy.

Prolonged exposure of dietary phytoestrogens on semen characteristics and reproductive performance of rabbit bucks

The effects of inclusion of different sources of dietary phytoestrogens on antioxidant capacity, hormonal balance, libido, semen quality, and fertility of rabbit bucks were studied. Twenty-one, adult, fertile, V-line bucks were randomly allocated into 3 homogenous groups (n = 7/treatment) and received control diet (phytoestrogens-free diet, CON) or soybean meal isoflavones–containing diet (SMI) or linseed meal lignans–containing diet (LML) for 12 wk. The diets were formulated to be isocaloric and isonitrogenous. The concentrations of isoflavones in the SMI diet were 24.04 mg/100 g dry matter (DM) daidzein and 13.10 mg/100 g DM genistein. The major phytoestrogen detected in the LML diet was secoisolariciresinol (36.80 mg/100 g DM). Treatment had no effects on body weight, feed intake and rectal temperature of bucks. Compared with control, bucks fed the SMI and LML diets had higher (P < 0.001) blood plasma total antioxidant capacity (0.98 ± 0.12, 1.50 ± 0.13, and 2.29 ± 0.17 mM/L for CON, SMI, and LML, respectively), and lower (P < 0.01) blood plasma malondialdehyde (2.76 ± 0.23, 1.76 ± 0.16, and 1.70 ± 0.18 nmol/mL for CON, SMI, and LML, respectively), whereas activities of reduced glutathione and superoxide dismutase (SOD) enzymes were not affected. Bucks fed the SMI and LML diets had greater (P < 0.001) concentrations of blood plasma triiodothyronine. Feeding the SMI and LML diets decreased (P < 0.01) libido (8.26 ± 0.71, 12.18 ± 0.97, and 14.12 ± 1.12 s for CON, SMI, and LML, respectively), sperm concentration (327.7 ± 21.6, 265.8 ± 36.8, and 226.5 ± 20.1 × 106/mL for CON, SMI, and LML, respectively), testosterone (5.16 ± 0.95, 3.91 ± 0.63, and 3.04 ± 0.92 ng/mL for CON, SMI, and LML, respectively), and seminal plasma fructose compared with the CON diet. The percentage of progressive motile sperm was improved (P < 0.001) by both phytoestrogen-containing diets. Feeding the SMI diet increased (P = 0.02) the percentage of live sperm compared with CON, whereas LML resulted in an intermediate value. Dietary treatment of bucks did not affect kindling rates or litter sizes of does, and did not affect birth weights or viabilities of kits. In conclusion, prolonged consumption of dietary isoflavones or lignans did not impair semen fertilizability. This may be due to the benefits of antioxidant activity or due to the benefits of other components in the diet. Dietary phytoestrogens did evoke obvious decreases in libido and steroidogenesis with altered semen parameters.

Indispensable Amino Acid–Deficient Diets Induce Seizures in Ketogenic Diet–Fed Rodents, Demonstrating a Role for Amino Acid Balance in Dietary Treatments for Epilepsy

Low protein amounts are used in ketogenic diets (KDs), where an essential (indispensable) amino acid (IAA) can become limiting. Because the chemically sensitive, seizurogenic, anterior piriform cortex (APC) is excited by IAA limitation, an imbalanced KD could exacerbate seizure activity. We questioned whether dietary IAA depletion worsens seizure activity in rodents fed KDs. In a series of 6 trials, male rats or gerbils of both sexes (6-8/group) were given either control diets (CDs) appropriate for each trial, a KD, or a threonine-devoid (ThrDev) diet for≥7 d, and tested for seizures using various stimuli. Microchip analysis of rat APCs was also used to determine if changes in transcripts for structures relevant to seizurogenesis are affected by a ThrDev diet. Glutamate release was measured in microdialysis samples from APCs during the first meal after 7 d on a CD or a ThrDev diet. Adult rats showed increased susceptibility to seizures in both chemical (58%) and electroshock (doubled) testing after 7 d on a ThrDev diet compared with CD (each trial, P≤ 0.05). Seizure-prone Mongolian gerbils had fewer seizures after receiving a KD, but exacerbated seizures (68%) after 1 meal of KD minus Thr (KD-T compared with CD, P<0.05). In kindled rats fed KD-T, both counts (19%) and severities (77%) of seizures were significantly elevated (KD-T compared with CD, P<0.05). Gene transcript changes were consistent with enhanced seizure susceptibility (7-21 net-fold increases, P=0.045-0.001) and glutamate release into the APC was increased acutely (4-fold at 20 min, 2.6-fold at 60 min, P<0.05) after 7 d on a ThrDev diet. Seizure severity in rats and gerbils was reduced after KDs and exacerbated by ThrDev, both in KD- and CD-fed animals, consistent with the mechanistic studies. We suggest that a complete protein profile in KDs may improve IAA balance in the APC, thereby lowering the risk of seizures.

Docosahexaenoic acid prevents resistance to antiepileptic drugs in two animal models of drug-resistant epilepsy

Objectives: One-third of epileptic patients are resistant to antiepileptic drugs. Few clinical studies with small sample size indicate that polyunsaturated fatty acids could control drug-resistant epilepsy. We examined the efficacy of acute and chronic administration of docosahexaenoic acid (DHA) in two animal models of drug-resistant epilepsies, i.e. 6-Hz psychomotor seizures in mice and lamotrigine (LTG)-resistant kindled rats.Methods: Mice received a single injection of DHA (300 µM, i.c.v.) along with phenytoin (PHT) or LTG (i.p.). Six-Hz electroshock (0.2 milliseconds rectangular pulse width, 3 seconds duration, 44 mA current) was given 15 minutes after DHA, and seizure behaviors were recorded. In LTG-resistant kindled rats, a single dose of DHA (300 µM, i.c.v.) was administered with LTG, and seizure parameters were measured. In chronic treatment, mice received DHA (0.1 g/day, orally) for 30 days. Then, a single dose of LTG or PHT was administered to mice and 6-Hz-induced seizures were recorded. In rats, DHA (1 µM, i.c.v.) was administered during kindling development and effect of LTG in DHA-pretreated LTG-resistant kindled rats was verified.Results: LTG and PHT did not inhibit 6-Hz seizures in mice after single injection of DHA. However, LTG and PHT inhibited 6-Hz seizures in mice that received DHA for 1 month. Acute or chronic administration of DHA to LTG-resistant kindled rats led to the suppression of kindled seizure parameters by LTG.Discussion: DHA removes the ‘inherent resistance’ of 6-Hz seizures to PHT and LTG, and prevents the development of pharmacodynamic tolerance to LTG in LTG-resistant kindled rats. DHA might have potential to be used as add-on therapy in patients with refractory epilepsy.

No differences in manic-like behaviors between voluntary ethanol and water drinking in Lateral Hypothalamic Kindled (LHK) alcohol preferring rats

This study investigates phenotypic differences of manic-like behaviors during voluntary ethanol (vs. water) intake in alcohol preferring (P) rats, using the lateral hypothalamus kindled (LHK) rat mania model. Alcohol preferring (P) rats exhibited classic manic-like behaviors during kindling and the post-kindling intervals in all coded behaviors (p < 0.0001), lending further validity to the lateral hypothalamus kindled rat as a useful model to study mania. However, there was no significant phenotypic difference between alcohol and water drinking alcohol preferring (P) rats.

Pharmacological Evaluation of Novel Flavone from Morus alba in Pentylenetetrazole-Induced Kindling and Oxidative Stress.

The present study was designed to explore the effect of chronic administration of a new flavone [morusflavone, 5,7,4'-trihydroxy-8-(γ,γ-dimethylallyl)-2',3'-(10'-hydroxy-9',10'-dimethyl-cyclohex-8-enyl)-flavone (compound 1)] at doses of 25, 50, and 100 mg/kg, orally (p.o.) to pentylenetetrazole-induced kindling in rats (a model of human epilepsy). Compound 1 and four other compounds were isolated from the stem bark of Morus alba. The structure of compound 1 was elucidated and established using standard spectroscopic techniques, and malondialdehyde (MDA) and glutathione (GSH) were estimated as oxidative markers in brain tissues of rodents. The progression of kindling in rats was effectively and significantly suppressed at doses of 25, 50, and 100 mg/kg of compound 1. In addition, increased the levels of MDA and decreased levels of glutathione were also reversed by compound 1 in kindled rats. Compound 1 treatment was able to restore the reduced glutathione level in the brain tissues of PTZ-kindled rats, thus proving its neuroprotective potential.

Low Frequency Stimulation Reverses the Kindling-Induced Impairment of Learning and Memory in the Rat Passive-avoidance Test.

Introduction:The life quality of patients with epileptic seizures is highly affected by cognitive deficits. Low Frequency Stimulation (LFS) is a novel approach for the treatment of pharmacoresistant epilepsy. The main goal of this research is investigating the possible effect of LFS on seizure-induced cognitive dysfunction.Methods:To this end, the kindled animal were prepared via CA1 electrical stimulation in a semi-rapid way (12 stimulations/day). A group of animals were stimulated with LFS, 4 times at 30 s, 6 h, 24 h, and 30 h after the last kindling stimulation. Applied LFS was administered in 4 packages every 5 minutes. The packages were designed with 200 monophasic 200 monophasic square wave pulses of 0.1 ms duration at 1 Hz. The passive-avoidance test was conducted on all animals in order to measure the learning and memory behavior.Results:Hippocampal kindled rats showed deficits in learning and memory when passive avoidance test was performed. Application of LFS reversed the impairment in learning and memory behavior in kindled rats. At the same time, LFS markedly diminished kindling-induced neuronal loss and atrophy in the hippocampus.Conclusion:LFS may have some protection against seizure-induced cognitive damage in kindled rats.

Effect of turmeric on the viability, ovarian folliculogenesis, fecundity, ovarian hormones and response to luteinizing hormone of rabbits

The present study investigated whether dietary turmeric (Curcuma longa L.) can improve rabbit reproduction, ovarian function, growth, or viability. Female New Zealand White rabbits were either fed a standard diet (n=15) or a diet enriched with 5 g (group E1) or 20 g (group E2) turmeric powder per 100 kg feed mixture (n=16 or 15, respectively). After 295 days, weight gain, conception and kindling rates, pup and mother viability, ovarian macro- and micro-morphometric indices, release of leptin in response to the addition LH, and the release of progesterone, testosterone and leptin by isolated ovarian fragments were analyzed. Dietary turmeric failed to affect ovarian length and weight but did increase the number of primary follicles (E2: 32.5% greater than control group), as well as the diameter of primary (E1: +19.4%, E2: +21.1%), secondary (E2: +41.4%), and tertiary (E1: +97.1%, E2: +205.1%) follicles. Turmeric also increased the number of liveborn (E1: +21.0%) and weaned (E1: +25.0%) pups and decreased the number of stillborn pups (E2: −87.5%) but did not affect weight gain, conception, or kindling rate. Furthermore, dietary turmeric decreased doe mortality during the first reproductive cycle (13.3% in control; 0% in E1; and 6.7% in E2) but not during the second cycle. In vitro, the ovaries of the turmeric-treated rabbits released more progesterone (E1: +85.7%, E2: +90.0%) and less testosterone (E2: −87.0%) and leptin (E2: −29.0%) than the ovaries of control rabbits. Moreover, LH decreased the leptin output of control rabbits but increased that of experimental rabbits. Therefore, it is likely that dietary turmeric improves pup viability and that it could promote rabbit fecundity by either (1) promoting the production of primary ovarian follicles or (2) stimulating the growth of follicles at all stages of folliculogenesis.

Effect of zonisamide on refractory epilepsy during pregnancy in lamotrigine resistant kindled rats.

Drug-resistant epilepsy with uncontrolled severe seizures despite state-of-the-art medical treatment continues to be a major clinical problem. Pregnancy is a state where drug pharmacokinetic changes are more pronounced and more rapid than any other period of life. The current study investigated the effect of zonisamide (ZNS) on refractory epilepsy during pregnancy in lamotrigine-resistant kindled rats. Fifty-six lamotrigine (LTG)-resistant kindled Wistar rats were divided into five experimental (four pregnant and one non-pregnant) and 2 positive controls (pregnant and non-pregnant) groups and eight intact Wistar rats were put in the negative pregnant control group. Experimental groups received daily ZNS 50mg/kg by oral gavage and 30min later, pentylenetetrazol (PTZ) (30mg/kg) was injected intraperitoneal (i.p) on Gestational Days 10-15 (in rats with or without ZNS or methanol and ethyl acetate as a ZNS solvent challenge in days -5 to 0) or Days 15-20 and for six days in the non-pregnant group. The positive control groups received the ZNS solvent for the same number of days, but the negative pregnant control group did not receive any treatment. Epilepsy was significantly controlled by ZNS in the experimental groups compared to the positive control groups. It was concluded that ZNS can control refractory epilepsy during pregnancy and increase pregnancy survival in refractory epileptic rats.

Behavioral and Neurochemical Consequences of Pentylenetetrazol-Induced Kindling in Young and Middle-Aged Rats.

(1) Objectives: Epilepsy disorder is likely to increase with aging, leading to an increased incidence of comorbidities and mortality. In spite of that, there is a lack of information regarding this issue and little knowledge of cognitive and emotional responses in aging subjects following epileptogenesis. We investigated whether and how aging distress epilepsy-related behavioral and biochemical outcomes are associated with cognition and emotion. (2) Methods: Young and middle-aged Wistar rats (3 or 12 months old) were treated with pentylenetetrazol (PTZ, 35 mg/kg) and injected on alternated days for 20 (young rats) and 32 days (middle-aged rats). Kindling was reached after two consecutive stages 4 plus one stage 5 or 6 in Racine scale. Control and kindled rats were evaluated in the elevated plus-maze (EPM) and object-recognition tests and their hippocampus was collected 24 h later for mitogen-activated protein kinases (MAPK) dosage. (3) Results: Middle-aged rats presented a higher resistance to develop kindling, with a decrease in the seizure severity index observed following the 4th and 9th PTZ injections. Middle-aged rats displayed an increased duration of the first myoclonic seizure and an increased latency to the first generalized seizure when compared to younger rats. The induction of kindling did not impair the animals’ performance (regardless of age) in the object-recognition task and the EPM test as well as it did not alter the hippocampal levels of MAPKs. (4) Significance: Our findings reveal that, despite age-related differences during epileptogenesis, middle-aged rats evaluated after kindling performed similarly during discriminative learning and emotional tasks in comparison to young animals, with no alteration of hippocampal MAPKs. Additional investigation must be carried out to explore the electrophysiological mechanisms underlying these responses, as well as the long-term effects displayed after kindling.

IMPACT OF LYCOPENE OR FOLIC ACID TREATMENT ON SEMEN QUALITY, BLOOD CONSTITUENTS AND FERTILITY OF RABBIT BUCKS

Effect of lycopene or folic acid supplementation in drinking water as enhancing factors on reproductive performance of NWZ rabbit bucks was investigated in this study. Total of 30 sexually adult bucks were homogeneously divided into 3 experimental groups (10 bucks/each). Bucks in the 1st, 2nd and 3rd group daily received drinking water supplemented with 0, 500 mg lycopene and 500 mg folic acid/l, respectively, for 4 weeks as a treatment period. Semen was collected twice/week for another six consecutive weeks. Blood constituents and semen quality were evaluated. At the end of the semen collection period, 90 NWZ does were divided into 6 groups (15/each). The 1st three groups were naturally mated with bucks treated with 0, lycopene or folic acid, while other three groups were artificially mated with pooled semen of each treated buck group. Results showed that lycopene or folic acid insignificantly increased final body weight and increased (P<0.05) water intake of bucks during treatment period. At the end of treatment period, both treatments increased (P<0.05) hemoglobin concentration, hematocrit value, count of red blood cells and platelets, serum total proteins, albumin, globulin, glucose and high density lipoproteins concentrations, while decreased (P<0.05) white blood cells count, and concentration of serum urea, creatinine, total lipids, triglycerides, total cholesterol and low density lipoproteins concentrations. Concentrations of total antioxidant and testosterone increased (P<0.05), while malondialdehyde concentration decreased (P<0.05) in treatment groups as compared to control. Both treatments improved (P<0.05) volume, quality and total sperm output, initial semen fructose concentration, conception and kindling rates, and litter size at birth of NZW does naturally or artificially mated by treated bucks, while decreased (P<0.05) semen pH value. Although both treatments had superiority in comparing with control, most blood constituents and semen traits were better (P<0.05) for lycopene than folic acid treatment. In conclusion, treatment of rabbit bucks with lycopene at a level of 500 mg/l drinking water or as oral administration of 105 mg/buck for 4 weeks prior to natural mating or semen collection could be useful as a strong antioxidant and could have interesting applications in rabbit farms.

Effects of Transcranial Direct Current Stimulation of Rat Cerebral Structures on Pentylenetetrazole-Induced Seizures

In rats with a kindling syndrome induced by injections of pentylenetetrazole (PTZ, 30.0 mg/kg, i.p., for three weeks), the latent periods of seizures induced by test doses of PTZ (30 mg/kg) were, on average, 37.5% greater than those in the control (P < 0.05) after transcranial direct current stimulation (TDCS, 600 μA, 15.0 min, cathode on the skull surface) oriented to the cerebellar cortex. Such stimulation prevented initiation of generalized clonico-tonic seizures; the duration of ictal discharges in brain structures decreased, on average, by 42.1% (P < 0.02). The latent periods of acute PTZ-induced (60.0 mg/kg) seizures in rats that were not subjected to the kindling procedure were 33.5% longer after TDCS (P < 0.05) than those in the control. Similar stimulation focused on the frontal cerebral cortex prevented the development of generalized seizures in 50% of the kindling rats (P < 0.05).

Lentiviral vector-mediated somatostatin overexpression suppresses seizures induced in hippocampal kindled rats

Objective To explore the effect of lentiviral vector-mediated somatostatin (SST) expression on seizures induced by hippocampal kindling in rats. Methods Adult Sprague-Dawley rats were randomly divided into the sham group (Sham), epilepsy group (EP), Lenti-pSyn-EGFP (LV-EGFP) group and Lenti-pSyn-SST-2A-EGFP (LV-SST) group.The rats in LV-EGFP group were subsequently electrically hippocampal kindled and LV-EGFP (5 μl) was injected into dentate gyrus (DG). The rats in LV-SST group were kindled and LV-SST (5 μl) was injected into the dentate gyrus (DG), medial entorhinal cortex (MEC) or amygdala (Amy). Seizure severity was evaluated and immunohistochemical staining was employed to detect the expression of SST, neuron specific nuclear protein (NeuN) and microtubule associated protein 2 (MAP2). Results The current values to the first stage V seizure of LV-SST (DG) group, LV-SST (MEC) group or LV-SST (Amy) group ((143.8±3.8)μA, (142.5±4.1)μA, (142.5±5.3) μA, respectively) were significantly increased compared with that of epilepsy (EP) group ((136.3±5.3)μA), and V stage current values of LV-SST groups in each stimulation day were higher than that of EP group except the fifth stimulation day (P<0.05). After kindling, SST expression and NeuN-positive neurons of EP group and LV-SST groups were less than that of Sham group in CA1, CA3 and DG. SST and NeuN neurons loss in LV-SST groups were less than that of EP group (P<0.05) and MAP2 immunohistochemistry stainings in LV-SST groups were higher than that in EP group. Conclusion Lentiviral vector-mediated somatostatin expression suppresses seizures and can rescue the neuronal damage of seizure induced by kindling in hippocampus, which may provide a new method of gene therapy for temporal lobe epilepsy. Key words: Epilepsy; Somatostatin; Hippocampus; Lentivirus; Gene therapy

Dichloro-substituted phenyl amino propanamides exhibit anticonvulsant effect and reduce inward sodium ion current (NaV1.6)

This research studied the anticonvulsant properties of three synthesized isomers of dichloro-substituted phenyl amino propanamides in rodents and determined their effects on votage-gated sodium channels (NaV1.6) stably expressed in Human Embryonic Kidney (HEK Cells 293). 2,3-, 2,5- and 3,4- Dichloro anilines were reacted with acrylamide according to Michael-type addition reaction to obtain their corresponding isomers; DCP23, DCP25 and DCP34. Each isomer was evaluated for anticonvulsant effects using maximal electroshock (MES)- and pentylenetetrazole (PTZ)- induced seizure models in mice; tested against PTZ-induced kindling in rats and its synergistic effect with fluphenamic acid in mice. Effects of DCP23 and DCP25 were studied on voltage-gated sodium channels (NaV1.6) at different states of the channel, using electrophysiology techniques. The test compounds generally offered dose dependent protection against maximal electroshock- and pentylenetetrazole (PTZ)- induced seizure; demonstrated synergistic effect when co-administered with fluphenamic acid; and produced significant (p<0.05) decrease in seizure progression in PTZ-kindled rats. DCP23 and DCP25 reduced sodium currents at different channel states in a concentration dependant manner. The results of this study showed that the compounds possess anticonvulsant effects and reduced the inward sodium currents. Therefore, they could exert anticonvulsant activity via sodium channels blockade.

Toxoplasmosis accelerates acquisition of epilepsy in rats undergoing chemical kindling

Epilepsy is one of the most common neurologic disorders worldwide with no distinguishable cause in 60% of patients. One-third of the world population has been infected with Toxoplasma gondii. This intracellular parasite has high tropism for excitable cells including neurons. We assessed impact of acute and chronic T. gondii infection on epileptogenesis in pentylenetetrazole (PTZ) kindling model in male rats. T. gondii cysts were administered to rats by intraperitoneal (i.p.) injection. The presence of T. gondii cysts in the brain of rats was verified by hematoxylin-eosin staining. One and eight weeks after cysts injection, as acute and chronic phases of infection, PTZ (30mg/kg, i.p.) was injected to the rats every other day until manifestation of generalized seizures. Histologic findings confirmed cerebral toxoplasmosis in rats. The rats with acute or chronic Toxoplasma infection became kindled by lower number of PTZ injections (14.8±1 and 13.6±1 injections, respectively) compared to corresponding uninfected rats (18.7±1 and 16.9±1 injections, p<0.05). Toxoplasma infection increased the rate of kindling in rats. The chronically-infected rats achieved focal and also generalized seizures earlier than the rats with acute infection. Toxoplasmosis might be considered as a risk factor for acquisition of epilepsy.

Yucca schidigera can promote rabbit growth, fecundity, affect the release of hormones in vivo and in vitro, induce pathological changes in liver, and reduce ovarian resistance to benzene

This study evaluated the effect of Yucca schidigera (YS) extract on the physiological, reproductive, and endocrine indexes of New Zealand White rabbit does. Six-week-old rabbit does were fed a standard diet (control group) or a diet enriched with 5 or 20g of Y powder extract per 100-kg feed mixture for 350days. The does were artificially inseminated after induction of superovulation. Weight gain; conception and kindling rate; viability of pups and mothers; histopathological state of liver and muscle; plasma levels of progesterone (P4), oxytocin (OT), and prostaglandin F (PGF); and the release of P4, insulin-like growth factor I (IGF-I), OT, and PGF by isolated ovarian fragments and their response to the addition of benzene were analyzed. YS extract supplementation promoted weight gain and induced histopathological changes in the liver (creased vacuolization and occurrence of fuchsinophile inclusions in hepatocytes, liver fibrosis, hyperemia, occurrence of Kupffer cells, signs of necrosis and inflammation). YS consumption was not associated with changes in muscle (occurrence of fuchsinophile inclusions and signs of atrophy, interstitial edema, and inflammation), although Y2 increased muscle vascularization. YS supplementation increased conception and kindling rates but did not affect viability of pups or adult animals. Moreover, it enhanced plasma OT and PGF levels; plasma P4 concentration was increased by low-dose YS, but decreased by high-dose YS. Cultured ovarian fragments isolated from YS-fed does released more P4 and PGF and less IGF-I than ovarian fragments of control animals. However, YS supplementation did not affect ovarian OT release. Benzene alone did not influence the release of hormones by ovaries of control does. YS supplementation induced the inhibitory effect of benzene on the release of PGF, but not on other ovarian hormones.Collectively, these results suggest that dietary supplementation of YS extract can stimulate rabbit performance (growth and fecundity), which may be due to the promotion of P4, OT, and PGF release. It could, however, induce some pathological changes in the liver and reduce resistance of ovaries to the environmental contaminant benzene.

Genetic resistance to kindling associated with alterations in circuit function

How a seizure spreads from a focal onset zone to other regions of the brain is not well understood, and animal studies suggest that there is a genetic influence. To understand how genetic factors may influence seizure spread, we examined whether the kindling resistance of WAG/Rij rats, which are slow to develop kindled motor seizures, is independent of the site of seizure induction and thus a global phenomenon, or whether it is circuit specific.We compared the kindling rates (number of stimulations to induce kindled motor seizures) of WAG/Rij rats to the rates of kindling in Sprague Dawley rats. Both groups underwent a standard hippocampal kindling protocol and a separate group was kindled from the medial dorsal nucleus of the thalamus, a site that has been previously demonstrated to result in the very rapid development of motor seizures. To examine whether there were differences in the interaction in a circuit involved with the motor seizures, evoked responses were obtained from the prefrontal cortex following stimulation of the subiculum or medial dorsal thalamic nucleus.The WAG/Rij rats once again demonstrated resistance to kindling in the hippocampus, but both strains kindled rapidly from the medial dorsal nucleus. In the WAG/Rij rats there was also a reduction in the duration of the afterdischarge in the frontal cortex during hippocampal stimulation, but there was no reduction during thalamic kindling. The prefrontal cortex evoked responses were reduced following stimulation of the subiculum in the WAG/Rij rats, but the evoked responses to thalamic stimulation were the same in both strains.These findings suggest that there are genetic influences in the strength of the input from the subiculum to the prefrontal cortex in WAG/Rij rats that could explain the resistance to limbic kindling because of reduced excitatory drive onto a key target region.

Effect of lamotrigine on seizure development in a rat pentylenetetrazole kindling model

IntroductionEpileptogenesis is a process of seizure development. Lamotrigine is a novel antiepileptic drug which is also used for antiepileptogenic research. Kindling models are recommended as potentially useful tools for antiepileptogenic treatment discovery. However, previous studies demonstrated that the antiepileptogenic effect of lamotrigine is controversial in the electrical kindling model. Chemical kindling such as with pentylenetetrazole is another kindling model. The aims of this study were to examine whether lamotrigine could prevent the development of seizure in pentylenetetrazole kindling rats.MethodsFemale rats were kindled by subconvulsive doses of pentylenetetrazole (35 mg/kg) once every other day for 15 times. Thereafter, the kindled rats received different doses of lamotrigine (5, 10 and 20 mg/kg) before pentylenetetrazole to observe the anticonvulsant effect. For the antiepileptogenic experiment, rats were kindled as the same way while pretreated (1 h) with different doses of lamotrigine (5, 10 and 20 mg/kg) before each injection of pentylenetetrazole. After a washout period for 1 week, the rats were administrated with pentylenetetrazole again for 3 times. The seizures were recorded each time. Later it was in vivo electrophysiological experiments followed with histologic analysis.ResultsFor the anticonvulsant experiment lamotrigine dose‐dependently suppressed pentylenetetrazole‐induced seizures. Here, 20 mg/kg of lamotrigine pretreatment significantly blocked the seizure development in rats for their seizure stages remained longer in 1–3 during the kindling phase. Mean seizure stages or generalized seizure durations in the 10 and 20 mg/kg lamotrigine pretreated groups were significantly lower or shorter when received 3 times of pentylenetetrazole after the washout period. Electrophysiological study also demonstrated 20 mg/kg of lamotrigine pretreatment obviously eliminated increased population spike amplitude in hippocampus. However, different doses of lamotrigine pretreatment could not alleviate severity of hippocampal neuronal damage.ConclusionsThe results suggest that adequate doses of lamotrigine can prevent seizure development in the pentylenetetrazole kindling rat model.

Detection of macrophages in rabbit semen and their relationship with semen quality

We aimed at the evaluating the occurrence of macrophages in rabbit semen and finding possible relationship between macrophage concentration and spermatozoa quality. The concentration of macrophages in semen samples from broiler rabbit males of lines M91 and P91 (n = 30) without overt evidence of genital tract infections was determined using monocyte/macrophage lineage antigen CD14 and flow cytometry. Then the rabbits were assigned into three groups according to the macrophage concentration in semen (MΦ1 group with less than 1 × 106 macrophages/mL, MΦ2 group with 1.5–3.5 × 106 macrophages/mL and MΦ3 group with more than 8 × 106 macrophages/mL). Spermatozoa viability parameters such as occurrence of apoptotic (Yo-Pro-1) and dead/necrotic (propidium iodide) spermatozoa and plasma membrane integrity (PNA-Fluos) were evaluated using flow cytometry. Sperm motility parameters were determined by CASA (Computer Assisted Semen Analysis). Ultrastructural detection of macrophages was performed using transmission electron microscopy. Spermatozoa fertility potential was examined after intravaginal artificial insemination of rabbit doses. Significantly higher proportions of the apoptotic and necrotic spermatozoa and spermatozoa with lower plasma membrane integrity were revealed in the MΦ3 group compared to MΦ1 and MΦ2 groups. The percentage value of total motility and progressive movement was significantly highest in the MΦ1 group, whilst lowest in the MΦ3 group. The conception rate and the kindling rate were significantly decreased in the group with the highest macrophage concentration (MΦ3). Based on our results we can conclude that the abundance of seminal macrophages in the rabbit semen may be closely associated with poor spermatozoa quality.