Saline-injected Group Research Articles

Extension of ischemic therapeutic time window by a free radical scavenger, Edaravone, reperfused with tPA in rat brain

3-methyl-1-phenyl-2-pyrazolin-5-one (Edaravone) is a free radical scavenger. We tested the hypothesis that combination treatment of Edaravone and recombinant tissue plasminogen activator (tPA) extends the therapeutic time window. Male Wistar rats were subjected to 1.5-, 3.0- or 4.5-hour middle cerebral artery (MCA) occlusion (MCAO) by a nylon thread. Animals were randomly divided into four groups. The Sham group rats were operated without MCAO and drug injection. In the Vehicle-treated group the same volume of saline was given every 1.5 hours from just after MCAO to just before reperfusion. In the Vehicle + tPA-treated group saline injection was given as above and tPA (5 mg/kg, i.v.) was given once just after reperfusion. Edaravone+tPA-treated group: Edaravone (3 mg/kg, i.v.) was given every 1.5 hours instead of saline and tPA injection as above. Survival rate, infarct size and evidence of apoptosis and hemorrhage were examined in the animals. Combining administration of Edaravone+tPAsignificantly increased survival rate after 3 hours of transient MCAO, and reduced infarct volume after 1.5 hours of transient MCAO compared with the vehicle or vehicle+tPAgroups. In Edaravone+tPA-treated group, the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) and 4-hydroxynonenal (4-HNE) positive cells were reduced at 16 hours after 3 hours of transient MCAO, but not in advanced glycation end products (AGEs) and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Hemorrhage rate and the area decreased in the Edaravone+tPA-treated group. The combination therapy of Edaravone+tPA increased survival rate, and reduced the infarct volume and hemorrhage with reduction of lipid peroxidation. Therefore, Edaravone combination is expected to extend the therapeutic time window of tPA in the clinical situation.

Basic fibroblast growth factor protects auditory neurons and hair cells from glutamate neurotoxicity and noise exposure

ObjectiveTo determine the protective effects of basic fibroblast growth factor (bFGF) on cochlear neurons and hair cells in vitro and in vivo.Material and MethodsIn Experiment I, cultured spiral ganglion neurons (SGNs) prepared from postnatal Day 3 mice were exposed to 20 mM glutamate for 2 h before the culture medium was replaced with fresh medium containing 0, 25, 50 or 100 ng/ml bFGF. Fourteen days later, all cultures were fixed with 4% paraformaldehyde and stained with 1% toluidine blue. The number of surviving SGNs was counted and the length of the neurites of the SGNs was measured. In Experiment II, in vivo studies were carried out with guinea pigs in which bFGF or normal saline was injected intramuscularly to assess possible protective effects of bFGF on cochlear hair cells and to accelerate the recovery of the auditory brainstem response (ABR). The ABRs were measured before, immediately after and 2 and 4 weeks after exposure to noise.ResultsExposure to 20 mM glutamate for 2 h resulted in an inhibition of neurite outgrowth of SGNs and an increase in cell death. Treatment of the cultures with bFGF led to promotion of neurite outgrowth and an increase in the number of surviving SGNs. In Experiment II, significant (p<0.05) differences in ABR thresholds were observed between the groups injected with bFGF and saline (t=2.689) at 4 weeks after noise exposure. Cochleae were removed and hair cell loss analyzed in surface preparations prepared from all experimental animals. Acoustic trauma caused loss of 240 and 2160 inner hair cells in the groups injected with bFGF and saline, respectively. Similarly, more outer hair cells were lost in the normal saline injection group (99 291) than in the group treated with bFGF (70 377).ConclusionsOur results demonstrate that bFGF protects SGNs against glutamate neurotoxicity in vitro. In addition, treatment with bFGF protects hair cells from acoustic trauma.

The effect of experimental epilepsy induced by penicillin administration during pregnancy on nestin expression in the immature rat cerebellum. A light, electron microscopic, and immunohistochemical study.

Recent knowledge regarding the effect of epileptic seizures in pregnant women on newborns was limited and, therefore, it was difficult to suggest the proper clinical guidelines and to take precautions against it. Studies evaluating the morphological effects of epileptic seizure during pregnancy on newborns in various experimental models are valuable. Therefore, the current study was designed to investigate the morphological changes in the cerebellum of newborn pups of rats subjected to experimental epilepsy during pregnancy. Swiss Albino rats were divided into three groups (six animals in each). In the first group (experimental group) an acute grand mal epileptic seizure was induced by 400 IU penicillin-G administration into their intrahippocampal CA3 region with a stereotaxic device during the 13th day of their pregnancy. The second group (intrahippocampal saline-injected sham group) and the third group (untreated animals) were the control groups. On the 1st neonatal day, pups were perfused with intracardiac fixative solution under anesthesia, and newborn cerebellums were dissected surgically for light and electron microscopic studies. In an immunohistochemical study using Rat-401 monoclonal antibody and peroxidase, the intermediate filament nestin was detected in the developing cerebellar tissue. Histologically, normal migration and cerebellar maturation were determined in the newborn rat cerebellum in the control and sham-operated groups. It was observed that the morphological structure of the cerebellar cortex in the experimental group was compromised in the early embryonal period. In contrast to the control and sham groups, it was found that nestin (+) cell density was increased in the experimental epilepsy group. It has been concluded that epileptic convulsions during embryonic life may cause early neurogenesis and delayed maturation, which explains the harmful effects of epileptic grand mal seizures, hypoxia, and obstetric trauma to the embryo at the early stage of neuronal differentiation. However, further studies are necessary to investigate epileptic pregnant phenomena and to characterize the possible relationship between epilepsy and congenital malformations as well as mental retardation.

정맥 주입용 산삼약침이 인체에 미치는 영향에 관한 임상적 연구

Background : This study was conducted to evaluate the effects of wild ginseng herbal acupuncture developed for the intravenous use. Healthy male and female volunteers(n=57) went through Randomized Control Trials(RCT). Methods : For those who are under a medication due to common cold or other illnesses were excluded in the primary stage and the subjects with possible abnormalities in the pre-screening process were also excluded in the secondary stage. Then the examination groups were determined by random sampling. Experiment groups were divided into Normal saline injection group(control group), cultivated wild ginseng herbal acupuncture group(experiment group 1) and natural wild ginseng herbal acupuncture group(experiment group 2) Blood tension, body temperature, pulse, and other criteria were measured and analyzed. Results : 1. Intravenous injection of cultivated wild ginseng herbal acupuncture and natural wild ginseng herbal acupuncture didn't cause significant changes in the blood tension, pulse, body temperature, and etc. 2. No significant differences were witnessed in CBC, ESR, biochemistry of blood test and UA between the experiment groups. 3. No significant changes were noted in the thermography before and after the test in the experiment groups. 4. Some of the common physical changes occurring during and after the administration were fatigue, chest distension, and headache in all of the experiment groups. 5. Comparing general condition after one week from the termination of administration, the control group showed worst condition while as the natural wild ginseng herbal acupuncture group displayed best condition. Conclusion : From the above results, we can carefully deduce that the intravenous injection of the wild ginseng herbal acupuncture didn't show significant differences compared to injection of the normal saline. We can infer it is safe on the human body and further studies and reports must be followed.

Erythropoietin improves place learning in fimbria–fornix-transected rats and modifies the search pattern of normal rats

The acquisition of a water-maze-based allocentric place learning task was studied in four groups of rats: two groups subjected to bilateral transections of the fimbria–fornix and two groups undergoing a sham control operation. At the moment of surgery all animals were given one systemic (intraperitoneal) injection of either human recombinant erythropoietin (EPO) (at a dosage of 5000 IU/kg body weight), given to one of the fimbria–fornix-transected groups and one of the sham-operated groups, or vehicle (saline), given to the two remaining groups. The 25-day task acquisition period (one session/day) began 6 or 7 days after the day of surgery. The fimbria–fornix-transected and saline-injected group exhibited a pronounced and long-lasting impairment of task acquisition. In contrast, the fimbria–fornix-transected and EPO-treated group demonstrated a less pronounced and more transient lesion-associated impairment. The two sham-operated groups did not differ with respect to the proficiency of task acquisition. But administration of EPO to intact animals caused a significant modification of swim patterns—apparently reflecting a somewhat modified strategy of task solution. It is concluded that systemic administration of EPO significantly improves the posttraumatic functional recovery of the presently studied place learning task after transections of the fimbria–fornix. Additionally, administration of EPO influences the strategy, although not quality, of task solution in normal (sham-operated) rats.

P.2.08 Acute hypercapnic gas challenge increases c-Fos in topographically organised histaminergic neurones

Inflammation is a factor in the aggravation of reperfusion injury after cerebral ischemia. Since histamine H2 receptor stimulation suppresses inflammatory reactions, effects of the central histaminergic activation on brain infarction were examined in rats. Focal cerebral ischemia for 2 h was provoked by transient occlusion of the right middle cerebral artery, and the infarct size was determined by 2,3,5-triphenyltetrazolium chloride stain after 24 h. Effects of postischemic administration of thioperamide, an H3 antagonist, and metoprine, an inhibitor of histamine-N-methyltransferase, were evaluated in rats treated with l-histidine, a precursor of histamine. Furthermore, effects of these agents on changes in the striatal histamine level were examined by a microdialysis procedure. Focal ischemia provoked marked damage in rats treated with l-histidine (1000 mg/kg) alone. Administration of l-histidine (1000 mg/kg) with either thioperamide (5 mg/kg) or metoprine (10 mg/kg) alleviated brain infarction. The size of brain infarction was 27% and 10% of that in animals treated solely with l-histidine, respectively. The combination treatment with thioperamide and metoprine decreased the size of brain infarction in rats given l-histidine (500 mg/kg), although protective effects were not clear without l-histidine. A marked increase in the histamine concentration was observed in the histidine plus metoprine group, the value being 363% of that in the saline-injected group after 2–3 h. The histamine concentrations in the histidine group and histidine plus thioperamide group were 188% and 248%, respectively. These findings indicate that facilitation of central histaminergic activity reduced the brain infarction.

Memory consolidation and reconsolidation of an inhibitory avoidance response in mice: effects of i.c.v. injections of hemicholinium-3

The immediate post-training i.c.v. administration of hemicholinium-3 (HC-3) (1 μg), a specific inhibitor of the high-affinity choline uptake (HACU) in brain cholinergic neurons, impaired retention test performance of a one-trial step-through inhibitory avoidance response in adult male CF-1 mice. The effect was observed in mice that received a footshock (0.8 mA, 50 Hz, 1 s) on the learning trial, and not only 48 h after training, but also 7 days after it. After the completion of the retention test at each of the training-test interval that were studied, the HACU in the hippocampus of HC-3-treated mice was not significantly different from that of saline-injected (1 μl) control groups. Mice that were over-reinforced (1.2 mA, 50 Hz, 1 s) on the learning trial, exhibited a high retention performance 48 h after training. The immediate i.c.v. injection of HC-3 (1 μg) after the retention test, that is, after memory reactivation, significantly impaired retention performance over 4 consecutive days, whereas the saline-injected control group shown a slight, but significant performance decrease only at the last retention test. Retention performance was unchanged in HC-3-treated mice not undergoing memory reactivation session. These results, taken together, indicate that HC-3, not only impaired consolidation, but also reconsolidation of an inhibitory avoidance task in mice, suggesting a critical participation of central cholinergic mechanisms in both memory processes.

Alleviation of ischemic neuronal damage by postischemic loading with histidine in the rat striatum

Inflammatory reactions play an important role in ischemia–reperfusion injury in the brain. Since histamine H 2 action suppresses inflammatory reactions, effects of postischemic loading with histidine, a precursor of histamine, were examined. Focal cerebral ischemia for 15 min was provoked by transient occlusion of the right middle cerebral artery in rats, and delayed neuronal death were evaluated in striatal neurons after 7 days. Histidine was administered four times, immediately, 6, 24, and 48 h after reperfusion of blood flow (1000 mg/kg, i.p., each time). To examine the role of histaminergic action on changes in histologic outcome, effects of mepyramine (3 nmol, i.c.v.), an H 1 antagonist, and ranitidine (30 nmol, i.c.v.), an H 2 antagonist, were evaluated in histidine-treated rats. Transient ischemia for 15 min provoked severe neuronal damage in the saline-injected control group, and the number of striatal neurons decreased to 21% of that on the contralateral side. Administration of histidine alleviated ischemic neuronal damage, and the number of preserved neurons was 76% of that on the contralateral side. Simultaneous administration of mepyramine with histidine did not affect the histologic outcome. However, administration of ranitidine abolished the alleviation by histidine. These findings indicate that the elevation of histamine H 2 receptor stimulation by massive administration of histidine suppresses reperfusion injury in the brain.

Alleviation of ischemic neuronal damage by histamine H 2 receptor stimulation in the rat striatum

Transient ischemia was produced for 15 min by occlusion of the middle cerebral artery in halothane-anesthetized rats, and changes in the extracellular concentrations of neurotransmitter monoamines and amino acids were examined in the striatum. The occlusion produced marked increases in the extracellular concentrations of both dopamine and glutamate in the striatum in the saline-injected control group, the peak values being 148 and 5.2 times those before ischemia, respectively. Preischemic administration of histamine (200 nmol, i.c.v.) suppressed the increase in dopamine and glutamate levels during ischemia, the peak values being 38% and 40% of those in the control group, respectively. Neither the dopamine nor glutamate level was affected by 6-[2-(4-imidazolyl)ethylamino]- N-(trifluoromethylphenyl)heptanecarboxamide (HTMT), an H 1 agonist (100 nmol, i.c.v.). However, dimaprit, an H 2 agonist (100 nmol, i.c.v.) suppressed the peak values to 42% and 32%, respectively. Most neurons were degenerated 7 days after ischemia in control animals. Histologic outcome was alleviated by either histamine or dimaprit treatment, whereas HTMT did not affect the outcome. Although postischemic administration of mepyramine, an H 1 antagonist (5 nmol, i.c.v.), did not affect the histologic alleviation caused by preischemic treatment with histamine, ranitidine, an H 2 antagonist (30 nmol, i.c.v.), partly abolished the improvement caused by histamine. These results suggest that suppression of ischemic release of excitatory neurotransmitters by histamine H 2 action is a contributing factor in alleviation of histologic outcome.

Prolonged effects of polyriboinosinic:polyribocytidylic acid on spontaneous running wheel activity and brain interferon-α mRNA in rats: a model for immunologically induced fatigue

Following 2 weeks acclimation to the running wheel in the home cages, an i.p. injection of a synthetic double-stranded RNA, polyriboinosinic:polyribocytidylic acid (poly I:C, 3 mg/kg), was performed to produce the immunologically induced fatigue in rats. The daily amounts of spontaneous running wheel activity decreased to about 40–60% of the preinjection level until day 9 with normal circadian rhythm, then gradually returned to the baseline level by day 14. Rats given a heat exposure (36 °C for 1 h) for the consecutive 3 days showed an increase in activity except for the first day. In the open field test, the total moving distance and the number of rearing of the poly I:C-injected rats decreased on day 1, but they were not different from the saline-injected group on day 7, suggesting that the poly I:C-induced fatigue on day 7 was not due to the peripheral problems such as muscle/joint pain, but involved the CNS. Quantitative analysis of mRNA levels using a real-time capillary reverse transcriptase-polymerase chain reaction (RT-PCR) method revealed that interferon-α (IFN-α) mRNA contents in the cortex, hippocampus, hypothalamic medial preoptic, paraventricular, and ventromedial nuclei were higher in the poly I:C group than those in the saline and heat-exposed groups on day 7, although the amount of interleukin-1β mRNA showed no differences. Serum adrenocorticotropic hormone and catecholamine levels were not significantly different between groups. The present results indicate that the prolonged fatigue induced by poly I:C, which is evaluated by the spontaneous running wheel activity, can be used as an animal model for the immunologically induced fatigue associated with viral infection, and suggest that brain IFN-α may play a role in this model.

Macrophage depletion improves survival of porcine neonatal pancreatic cell clusters contained in alginate macrocapsules transplanted into rats.

Macrophages can accumulate on the surface of empty and islet-containing alginate capsules, leading to loss of functional tissue. In this study, the effect of peritoneal macrophage depletion on the biocompatibility of alginate macrocapsules and function of macroencapsulated porcine neonatal pancreatic cell clusters (NPCCs) was investigated. Clodronate liposomes were injected into the peritoneal cavities of normoglycemic Lewis rats 5 and 2 days before the transplantation. Empty or NPCC-containing Ca-alginate poly L-lysine (PLL)-coated macrocapsules were transplanted into the peritoneal cavities of rats injected with either clodronate liposomes or saline. On days 7, 14 and 21, samples were evaluated by immunohistochemistry for cellular immune responses on the surface of the macrocapsules and for macrophage populations in omental tissue. To assess the function of macroencapsulated NPCCs, insulin secretory responses to glucose and theophylline were measured after capsule retrieval. In saline-injected control groups, all of the empty and NPCC-containing macrocapsules were overgrown with macrophages, this being especially severe on NPCC-containing macrocapsules. In the clodronate liposomes-injected group, the majority of the empty macrocapsules were free of macrophage accumulation and the NPCC-containing macrocapsules were less overgrown than in control animals. Higher insulin responses to glucose and theophylline were observed in NPCCs retrieved from rats injected with clodronate liposomes. We conclude that depletion of peritoneal macrophages with clodronate liposomes improve the survival of macroencapsulated NPCCs.

Expression of dominant-negative form of ETS-1 efficiently suppresses tumorigenesis in pancreatic cancer cells

Ets-1, part of the Ets family of transcription factors and highly expressed in malignant tumors and anglogenic vessels, controls the invasive process. Eta-1 controls the expression of critical genes involved in these processes by binding to Eta binding sites located in the transcriptional regulatory regions of various downstream genes encoding matrix metalloproteinases or adhesion molecules. In this study, we hypothesised that transcriptional inhibition of Eta-1 could be a tbe~peutic target for pancreatic adenocarcinoma, one of the most lethal digestive Iumor To this/~nd, we investigated the effect of Ets-1 suppression in a few pancreatic cancer cells using an'adenovims vector that encodes only the DNA binding domain of wild-type Eta-1 (Ets-DN), acting in a dominant negative manner over Eta-l, by competing the DNAbinding. Ets-DN bound to DNA with higher affinity than wild-type Eta-l, and inhibited the endogenous Ets-1 binding to DNA as seen by electrophomtic mobility shift assay. Adenoviral mediated transfer of Ets-DN (AdEts-DN) in pancreatic tumor cell lines did not affected their proliferation rate in vitro, but significantly inhibited their in vivo growth in immunodeficient mice (SCID) model. Furthermore, to test the efficacy of Ets-DN in vivo, we injected the AdEts-DN into preestablished human pancreatic adenocarcinomas grown in SCID mice. After the fifth injection, there was nearly a 70% reduction of tumor size in the AdEtsDN-treated group compared with the saline-injected control group (P = 0.031), without detectable side effects. Micro-vessel density in SCID mice xenografts demonstrated significantly lower neovascularizatinn in tumors with down-regulated Ets-1. The expression of PCNA, a nuclear marker of cell proliferation, showed that 6% stained positive for PCNA in the AdEts-DN -treated tumors compared with 15% in the saline-treated tumors. In addition, expression of the Ets-DN in the pancreatic cancer cells resulted in down-regulation of uPA and MMP-1 expression as proved by northern blotting and CATpromoter assays. Taken together these data suggest that transcriptional inactivation of Ets-1 was able to significantly suppress the tumorigenic and angioganic phenotype of the pancreatic cancer cells in part through down-regnlation of MMP1 and uPA expression. Due to various targets of Ets-1 it is conceivable to believe that most of the recorded result could be accounted by a real multi-targeting effect in which variable number of genes are simultaneously deregulated in downstream of Ets-1. These characteristics of Ets-DN make it a promising candidate for in ~Wo gene therapy.

Effects of Steroid and Nonsteroidal Anti-inflammatory Drugs on Acute Wound Healing and Collagen Synthesis in Rat Skin

Purpose : We studied short-term effects of steroid and anti-inflammatory drugs on collagen synthesis in rat skin. Materials and Methods : The 18 rats were divided equally into three groups: group I; piroxicam, group II; triamcinolone, group III; saline. All drugs were given by intraperitoneal injection. Drugs were administered to rats for 4 days after dorsal skin incision. One day after operation and at 24 hour interval there after, skin tissues containing subcutaneous fat were randomly harvested. Measurement procedures were composed of three steps: the first was Masson’ trichrome stain for collagen tissue identification; the second involved transporting the image to a computer and the third the analyses of the collagen area using a morphometry program. Results : Statistically significant differences were found in the mean values of the relative collagen contents of the triamcinolone and saline injection groups on the third day (p

Ih blockers have a potential of antiepileptic effects.

The h current (Ih) is an inwardly mixed cationic conductance activated by membrane hyperpolarization and distributed predominantly in the apical dendrites of hippocampal pyramidal neurons. To verify a hypothesis that an anomalous hyperpolarization generates an abnormal excitation by way of Ih channels, we examined the effects of Ih blockers (CsCl and ZD7288) on electrically induced paroxysmal discharges (PADs). Fifty-three adult male rabbits were used. We measured the PAD threshold elicited by stimulation to the apical dendritic layer of the hippocampal CA1 region before and after injecting 50 microl of each Ih blocker or saline extracellularly into the same region. In Ih blocker injection groups (n = 26), we obtained a significant increase in PAD threshold (1 mM CsCl: 163%, p < 0.01; 10 mM CsCl: 265%, p < 0.01; 100 mM CsCl: 199%, p < 0.01; 100 microM ZD7288: 192%, p < 0.05; 1 mM ZD7288: 246%, p < 0.05). Conversely, we did not obtain the increase in PAD threshold in a saline injection group (n = 10, 107%). The magnitude as well as duration of the effect had a tendency to depend on concentration of Ih blockers, although a saturated or declining tendency was observed with the 100 mM CsCl injection. We concluded that Ih channels might contribute to hippocampal epileptiform discharges in vivo. Our hypothesis for epileptogenesis demonstrated in the present experiment offers an idea to develop a new type of antiepileptic drug based on Ih blockers for the treatment of epileptic disorders refractory to current medications.

The effects of alpha interferon on the development of autoimmune thyroiditis in the NOD H2h4 mouse.

Alpha interferon (αIFN) therapy is known to induce thyroid autoimmunity in up to 40% of patients. The mechanism is unknown, but Th1 switching has been hypothesized. The aim of our study was to examine whether αIFN accelerated the development of thyroiditis in genetically susceptible mice. We took advantage of NOD-H2h4, a genetically susceptible animal model, which develops thyroiditis when fed a high iodine diet. Six to eight week old male NOD H2h4 mice were injected with mouse αIFN (200 units) or with saline three times a week for 8 weeks. All mice drank iodinated water (0.15%). Mice were sacrificed after 8 weeks of injection. Their thyroids were examined for histology and blood was tested for antithyroglobulin antibody levels. T4 and glucose levels were also assessed. In the IFN-injected group, 6/13 (46.2%) developed thyroiditis and/or thyroid antibodies while in the saline-injected group, only 4/13 (30.8%) developed thyroiditis and/or thyroid antibodies (p=0.4). The grade of thyroiditis was not different amongst the two groups. None of the mice developed clinical thyroiditis or diabetes mellitus. Our results showed that αIFN treatment did not accelerate thyroiditis in this mouse model. This may imply that αIFN induces thyroiditis in a non-genetically dependent manner, and this would not be detected in a genetically susceptible mouse model if the effect were small. Alternatively, it is possible that αIFN did not induce thyroiditis in mice because, unlike in humans, in mice αIFN does not induce Th1 switching.

Hippocampal long-term potentiation attenuated by lesions in the marginal division of neostriatum.

The marginal division (MrD) is a spindled-neurons consisted zone at the caudal border of the neostriatum in the mammalian brain and has been verified as contributing to associative learning and declarative memory in the rat and human with behavior and functional magnetic resonance imaging methods. It was proved to have functional connections with the limbic system. Whether the MrD has influence on the hippocampal long-term potentiation (LTP) was investigated in this study. LTP was induced from the dentate gyrus (DG) in the hippocampus by high-frequency stimulation (HFS) to the perforant path (PP). The amplitude of the population spike (PS) and the slope of the excitatory postsynaptic potential (EPSP) increased significantly to form LTP in the DG of the hippocampus after HFS of PP in normal and saline-injected control groups of rats. Lesions introduced in the MrD reduced significantly both the amplitude of PS and the slope of the EPSP following HFS of the PP. The results indicated that lesions in the MrD could attenuate LTP formation in the hippocampus. Our data suggest that the MrD might very possibly have excitatory functional influence on the hippocampus and therefore might influence the function of the hippocampus.

Effect of methyl parathion on the susceptibility of shrimp Litopenaeus vannamei to experimental vibriosis

Following increasing calls for environmental safety over the past 2 decades, persistent pesticides are being replaced by more rapidly degradable products. However, even these pesticides can affect non-target species, and may be associated with slow growth and increased susceptibility to viral and bacterial infections. In this study, juvenile white shrimp Litopenaeus vannamei (also named Penaeus vannamei) were challenged by intramuscular injection with Vibrio parahaemolyticus after 4 d prior exposure to methyl parathion in feed pellets at 0.080 microg g(-1). The bacterial injection control group consisted of shrimp fed pellets containing the methyl parathion-carrier solvent acetonitrile. Three additional control groups comprised 2 sterile saline-injection groups fed pellets containing methyl parathion or acetonitrile prior to injection, and 1 uninjected group fed normal pellets. Cumulative mortalities were recorded on the 4th and 8th days, and the presence of histological lesions was recorded on the 8th day. Cumulative mortalities were significantly higher in the group exposed to methyl parathion and bacteria on Day 8. Histological lesions, typical of vibriosis, were significantly associated with the injection of V. parahaemolyticus. The study provides strong experimental evidence that prior exposure to methyl parathion can increase the severity of Vibrio infections.

Esophageal, Tracheal and Pulmonary Parenchymal Alterations in Experimental Esophageal Atresia and Tracheoesophageal Fistula

Pulmonary complications are among the most important causes of morbidity and mortality in neonates with esophageal atresia and tracheofistula. We aimed to investigate the possible causes of respiratory complications encountered in esophageal atresia (EA) and tracheoesophageal fistula (TEF) in an experimental model. Sprague-Dawley fetal rats treated with adriamycin were used for the experiment. Time mated pregnant rats were given 1.75 mg/kg of adriamicyn intraperitoneally on days 6–9 of gestation. The fetuses were sacrified on day 21, weighed, and dissected under the surgical microscope. The animals were divided into four groups: (1) control group; (2) saline-injected group; (3) adriamycin-induced EA group, and (4) adriamycin administered but without development of EA. The lungs, esophagus, and trachea were excised and underwent histological examination. The mucosa of distal esophagus was thickened (p < 0.05); the submucosa was thinner (p < 0.05); and the muscular layer was thickened (p < 0.05) in fetuses with EA and TEF. In adriamycin-treated rats, in which EA and TEF developed, tracheal cartilage was loosened and formed into a D or C shape. The cartilage was fragmented into several segments on transverse sections in most fetuses. Alveolar septa were thin in lungs of fetus with EA and TEF (p < 0.05), without any fibrosis or evidence of parenchymal abnormality microscopically. Our findings suggest that respiratory complications may contribute to structural lesions in the trachea and particularly in the distal esophagus but not in the pulmonary parenchyma itself.

Changes in synaptic plasticity in the rat hippocampo-medial prefrontal cortex pathway induced by repeated treatments with fluvoxamine

The present studies were conducted to examine the effects of single and repeated treatments with fluvoxamine, which is a selective serotonin reuptake inhibitor (SSRI), on the synaptic efficacy and synaptic plasticity in the rat hippocampo-medial prefrontal cortex (mPFC) pathway in vivo. It has been reported that the projections arising from the hippocampal structures to the mPFC are involved in the execution of higher cognitive functions in rats. The evoked potentials were recorded in the mPFC by stimulation of the CA1/subicular region of the ventral hippocampus in halothane-anesthetized rats. Single administration of fluvoxamine (10 and 30 mg/kg, i.p.) enhanced synaptic efficacy in the hippocampo-mPFC pathway in a dose-dependent manner. Although repeated treatments with fluvoxamine (30 mg/kg, i.p. after 30 mg/kg/day×21 days, p.o.) caused an enhancement of synaptic efficacy, there was no significant difference between single and repeated treatments. The input/output characteristics showed hypersensitivity to stimulation intensity in the group with repeated fluvoxamine treatments. The establishment of long-term potentiation (LTP) in the hippocampo-mPFC pathway after a single administration of fluvoxamine was not different from that in the saline-injected group. On the other hand, the hippocampo-mPFC LTP was significantly augmented by repeated treatments with fluvoxamine when compared to a single treatment. These findings suggest that the serotonergic system could modulate the synaptic plasticity at hippocampal-mPFC synapses. The present study, furthermore, suggests that the enhancement of LTP in the hippocampo-mPFC pathway produced by repeated treatments with fluvoxamine may be implicated in the SSRI-induced therapeutic effect on psychiatric disorders.

Clozapine and Haloperidol Reinstate Latent Inhibition Following its Disruption during Amphetamine Withdrawal

Latent inhibition (LI) is a behavioral phenomenon whereby repeated exposure to a non-reinforced stimulus retards subsequent conditioning to that stimulus. Deficits in LI may reflect an inability to ignore irrelevant stimuli and are studied as a model of the cognitive/attentional abnormalities found in schizophrenia. We recently determined that pretreatment with escalating doses of the indirect dopamine agonist amphetamine (AMPH; 3 daily injections ip, 1-5 mg/kg, over 6 days) disrupts LI in rats tested in a 2-way active avoidance paradigm during withdrawal. In the present study, we evaluated the effects of the atypical neuroleptic clozapine and the typical neuroleptic haloperidol on the expression of LI on day 4 of AMPH withdrawal. Neuroleptic injections were given either 45 min prior to each of two tone preexposure sessions and a subsequent tone-shock avoidance test session, or only prior to the test session. As expected, saline-injected control groups showed LI during the test session, as reflected by significantly reduced avoidance in tone preexposed vs. non-preexposed rats. In contrast, animals pretreated with escalating doses of AMPH did not show LI, due to the improved avoidance of the preexposed animals. Both haloperidol (0.03 mg/kg) and clozapine (5 mg/kg) largely reversed the disruptive influence of AMPH on LI regardless of whether these drugs were administered prior to both preexposure and test sessions or only prior to the test session. These results provide pharmacological validation for an AMPH withdrawal model of schizophrenic symptoms.