Reduced Hippocampal Dendritic Spine Density and BDNF Expression following Acute Postnatal Exposure to Di(2-Ethylhexyl) Phthalate in Male Long Evans Rats

Early developmental exposure to di(2-ethylhexyl) phthalate (DEHP) has been linked to a variety of neurodevelopmental changes, particularly in rodents. The primary goal of this work was to establish whether acute postnatal exposure to a low dose of DEHP would alter hippocampal dendritic morphology and BDNF and caspase-3 mRNA expression in male and female Long Evans rats. Treatment with DEHP in male rats led to a reduction in spine density on basal and apical dendrites of neurons in the CA3 dorsal hippocampal region compared to vehicle-treated male controls. Dorsal hippocampal BDNF mRNA expression was also down-regulated in male rats exposed to DEHP. No differences in hippocampal spine density or BDNF mRNA expression were observed in female rats treated with DEHP compared to controls. DEHP treatment did not affect hippocampal caspase-3 mRNA expression in male or female rats. These results suggest a gender-specific vulnerability to early developmental DEHP exposure in male rats whereby postnatal DEHP exposure may interfere with normal synaptogenesis and connectivity in the hippocampus. Decreased expression of BDNF mRNA may represent a molecular mechanism underlying the reduction in dendritic spine density observed in hippocampal CA3 neurons. These findings provide initial evidence for a link between developmental exposure to DEHP, reduced levels of BDNF and hippocampal atrophy in male rats.     

Short-term alterations in hippocampal glutamate transport system caused by one-single neonatal seizure episode: implications on behavioral performance in adulthood

Impairment in the activity and expression of glutamate transporters has been found in experimental models of epilepsy in adult animals. However, there are few studies investigating alterations on glutamate transporters caused by epilepsy in newborn animals, especially in the early periods after seizures. In this study, alterations in the hippocampal glutamate transporters activity and immunocontent were investigated in neonatal rats (7 days old) submitted to kainate-induced seizures model. Glutamate uptake, glutamate transporters (GLT-1, GLAST, EAAC1) and glutamine synthetase (GS) were assessed in hippocampal slices obtained 12 h, 24 h, 48 h, 72 h and 60 days after seizures. Immunoreactivity for hippocampal GFAP, NeuN and DAPI were assessed 24 h after seizure. Behavioral analysis (elevated-plus maze and inhibitory avoidance task) was also investigated in the adult animals (60 days old). The decrease on glutamate uptake was observed in hippocampal slices obtained 24 h after seizures. The immunocontent of GLT-1 increased at 12 h and decreased at 24 h (+62% and −20%, respectively), while GLAST increased up to 48 h after seizures. No alterations were observed for EAAC1 and GS. It should be mentioned that there were no long-term changes in tested glutamate transporters at 60 days after kainate treatment. GFAP immunoreactivity increased in all hippocampal subfields (CA1, CA3 and dentate gyrus) with no alterations in NeuN and DAPI staining. In the adulthood, kainate-treated rats showed anxiety-related behavior and lower performance in the inhibitory avoidance task. Our findings indicate that acute modifications on hippocampal glutamate transporters triggered by a single convulsive event in early life may play a role in the behavioral alterations observed in adulthood.     

Sexually dimorphic effects of maternal alcohol intake and adrenalectomy on left ventricular hypertrophy in rat offspring

In humans, low birth weight and increased placental weight can be associated with cardiovascular disease in adulthood. Low birth weight and increased placental size are known to occur after fetal alcohol exposure or prenatal glucocorticoid administration. Thus the effects of removing the alcohol-induced increase in maternal corticosterone by maternal adrenalectomy on predictors of cardiovascular disease in adulthood were examined in rats. Alcohol exposure of dams during the last 2 wk of gestation resulted in significantly decreased fetal weight and increased placental weight on gestational day 21. Adult female, but not male, offspring of alcohol-consuming mothers exhibited left ventricular hypertrophy. Placental 11beta-hydroxysteroid dehydrogenase-2 (11beta-HSD-2) mRNA levels, measured by Northern blot, were decreased in females but not males. Adrenalectomy of alcohol-consuming dams reversed the increase in placental weight and the decrease in female placental 11beta-HSD-2 expression and eliminated the left ventricular hypertrophy of adult female offspring. These data suggest that alcohol-induced changes in placental 11beta-HSD-2 mRNA levels and left ventricular weight are coupled in female offspring only and depend on maternal adrenal status.     

Changes in iNOS,GFAP and NR1 Expression in Various Brain Regions and Elevation of Sphingosine-1-phosphate in Serum after Immobilized Stress

Several studies have been suggested that long-term exposure to stress has detrimental effects on various brain functions and leads to neurodegenerative changes. However, the precise mechanism by which stress induces brain damage or neurodegenerative change is still a matter of debate. This study investigated the damage of neuronal cells involving in the expression of iNOS, NR1, and GFAP in various brain regions and characterized the change of sphingolipid metabolites as a biomarker of physiological change in serum after 3 weeks of repeated immobilization. In this report, the expression of iNOS, GFAP and NR1 in the brain of rats exposed to chronic immobilization stress was investigated. The expression of iNOS, GFAP and NR1 was elevated in the cortex and hippocampal area after 3 weeks of repeated immobilization. Immunoreactivity for GFAP and vimentin, as a marker of reactive gliosis, was also elevated in the cortex and hippocampus. The level of sphingolipids was measured in order to assess the changes in sphingolipid metabolites in the serum of rats exposed to stress. Interestingly, the level of So-1-P was increased in the plasma of rats subjected to 6-h immobilization stress than repeated immobilization. To further investigate the modulating effect of increased So-1-P in various brain regions, So-1-P was infused into the lateral cerebroventricle at a rate of 100 pmol/10 μl/h for 7 days. The expression of iNOS and NR1 was elevated in the cortex, hippocampus, striatum, and cerebellum after So-1-P infusion into the cerebroventricle, while the level of GFAP was elevated in the hippocampus and striatum. Interestingly, the expression levels of iNOS, GFAP, and NR1 were increased by the direct application of So-1-P to cultured cortical cells. These results suggest that NO production via iNOS expression, the NR1 expression, the activation of astrocytes, and the elevation of So-1-P may cause neurodegenerative changes in rats subjected to chronic immobilization and that the elevation of So-1-P by stress exposure would be one of the stress signal molecules.     

Sex differences,laterality, and hormonal regulation of androgen receptor immunoreactivity in rat hippocampus

Sex differences, laterality, and hormonal regulation of androgen receptor (AR) immunoreactivity in rat hippocampal CA1 pyramidal cells were examined using the PG21 antibody. Adult male rats were either castrated or sham-operated at least 2 weeks prior to sacrifice. Gonadally intact females were sacrificed on the day of proestrus. Animals received an injection of either testosterone propionate (TP) or vehicle 2 h prior to sacrifice. Within CA1, both the intensity of staining and the number of AR+ cells were assessed. AR immunostaining was detected in all the groups with marked variation among them. The overall ranking of staining intensity was: gonadally intact males > females given TP > castrated males given TP > females > castrated males given vehicle. The number of AR+cells within subregions of CA1 showed the same basic pattern: among control-treated animals, gonadally intact males have more than females, but castrated males have the least, and acute TP treatment increases the number in both sexes. The increased level of AR immunoreactivity in CA1 of castrated males following acute TP treatment suggests that testicular androgens in adulthood normally increase AR immunoreactivity there, producing a sex difference favoring males in gonadally intact animals. We also found a higher number of AR+ CA1 cells on the left than on the right, but only in gonadally intact males and in females given TP. These results suggest that a laterality of AR distribution in the rat hippocampus may lead to lateralities in hippocampal structure and function.     

Genetic Enhancement of Memory and Long-Term Potentiation but Not CA1 Long-Term Depression in NR2B Transgenic Rats

One major theory in learning and memory posits that the NR2B gene is a universal genetic factor that acts as rate-limiting molecule in controlling the optimal NMDA receptor''s coincidence-detection property and subsequent learning and memory function across multiple animal species. If so, can memory function be enhanced via transgenic overexpression of NR2B in another species other than the previously reported mouse species? To examine these crucial issues, we generated transgenic rats in which NR2B is overexpressed in the cortex and hippocampus and investigated the role of NR2B gene in NMDA receptor-mediated synaptic plasticity and memory functions by combining electrophysiological technique with behavioral measurements. We found that overexpression of the NR2B subunit had no effect on CA1-LTD, but rather resulted in enhanced CA1-LTP and improved memory performances in novel object recognition test, spatial water maze, and delayed-to-nonmatch working memory test. Our slices recordings using NR2A- and NR2B-selective antagonists further demonstrate that the larger LTP in transgenic hippocampal slices was due to contribution from the increased NR2B-containing NMDARs. Therefore, our genetic experiments suggest that NR2B at CA1 synapses is not designated as a rate-limiting factor for the induction of long-term synaptic depression, but rather plays a crucial role in initiating the synaptic potentiation. Moreover, our studies provide strong evidence that the NR2B subunit represents a universal rate-limiting molecule for gating NMDA receptor''s optimal coincidence-detection property and for enhancing memory function in adulthood across multiple mammalian species.     

Minocycline Attenuates Cognitive Impairment Induced by Isoflurane Anesthesia in Aged Rats

Postoperative cognitive dysfunction (POCD) is a clinical phenomenon characterized by cognitive deficits in patients after anesthesia and surgery, especially in geriatric surgical patients. Although it has been documented that isoflurane exposure impaired cognitive function in several aged animal models, there are few clinical interventions and treatments available to prevent this disorder. Minocycline has been well established to exert neuroprotective effects in various experimental animal models and neurodegenerative diseases. Therefore, we hypothesized that pretreatment with minocycline attenuates isoflurane-induced cognitive decline in aged rats. In the present study, twenty-month-old rats were administered minocycline or an equal volume of saline by intraperitoneal injection 12 h before exposure to isoflurane. Then the rats were exposed to 1.3% isoflurane for 4 h. Two weeks later, spatial learning and memory of the rats were examined using the Morris Water Maze. We found that pretreatment with minocycline mitigated isoflurane-induced cognitive deficits and suppressed the isoflurane-induced excessive release of IL-1β and caspase-3 in the hippocampal CA1 region at 4 h after isoflurane exposure, as well as the number of TUNEL-positive nuclei. In addition, minocycline treatment also prevented the changes of synaptic ultrastructure in the hippocampal CA1 region induced by isoflurane. In conclusion, pretreatment with minocycline attenuated isoflurane-induced cognitive impairment in aged rats.     

Neonatal infection produces significant changes in immune function with no associated learning deficits in juvenile rats

The current experiments examined the impact of early‐life immune activation and a subsequent mild immune challenge with lipopolysaccharide (LPS; 25µg/kg) on hippocampal‐dependent learning, proinflammatory cytokine expression in the brain, and peripheral immune function in juvenile male and female rats at P24, an age when hippocampal‐dependent learning and memory first emerges. Our results indicate that neonatal infection did not produce learning deficits in the hippocampal‐dependent context pre‐exposure facilitation effect paradigm in juvenile males and females, contrary to what has been observed in adults. Neonatal infection produced an increase in baseline IL‐1β expression in the hippocampus (HP) and medial prefrontal cortex (mPFC) of juvenile rats. Furthermore, neonatally infected rats showed exaggerated IL‐1β expression in the HP following LPS treatment as juveniles; and juvenile females, but not males, showed exaggerated IL‐1β expression in the mPFC following LPS treatment. Neonatal infection attenuated the production of IL‐6 expression following LPS treatment in both the brain and the spleen, and neonatal infection decreased the numbers of circulating white blood cells in juvenile males and females, an effect that was further exacerbated by subsequent LPS treatment. Together, our data indicate that the consequences of neonatal infection are detectable even early in juvenile development, though we found no concomitant hippocampal‐dependent learning deficits at this young age. These findings underscore the need to consider age and associated on‐going neurodevelopmental processes as important factors contributing to the emergence of cognitive and behavioral disorders linked to early‐life immune activation. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1221–1236, 2017     

Sex and estrous cycle-dependent differences in glial fibrillary acidic protein immunoreactivity in the adult rat hippocampus

Sex differences in the morphology and function of the hippocampus have been reported in several species, but it is unknown whether a sexual dimorphism exists in glial fibrillary acidic protein (GFAP) expression in the rat hippocampus. We analyzed GFAP immunoreactivity in the hippocampus of intact adult male rats as well as in females during diestrus and proestrus phases of the estrous cycle. We found that in CA1, CA3, and dentate gyrus, GFAP immunoreactivity was higher in proestrus females as compared with males and diestrus females. In CA1, a similar GFAP immunoreactivity was found in males and in diestrus females, but in dentate gyrus, males presented the lowest GFAP content. Interestingly, differences in astrocyte morphology were also found. Rounded cells with numerous and short processes were mainly observed in the hippocampus during proestrus whereas cells with stellate shape with few and long processes were present in the hippocampus of males and diestrus females. The marked sex and estrous cycle-dependent differences in GFAP immunoreactivity density and in astrocyte number and morphology found in the rat hippocampus, suggest the involvement of sex steroid hormones in the sexually dimorphic functions of the hippocampus, and in the change in its activity during the estrous cycle.     

癫痫大鼠海马NMDA受体亚基NR2A和BDNFmRNA水平的检测

目的通过锂一匹罗卡品癫痫模型（ithium—pilocarpine seizures rats model of epilepsy,LPS）,研究NMDA受体亚基NR2A、BDNF mRNA的表达,探讨NR2A、BDNF在LPS中的作用。方法建立氯化锂-匹罗卡品大鼠模型,运用原位杂交技术检测致痫后各组不同时间点海马CAI、CA3及DG区NR2A与BDNF mRNA的表达。结果LPS海马NR2A、BDNF mRNA在各观察时间点及部位模型组与正常对照组比较均有明显上调,且有显著统计学差异（P〈0．05）。模型组NR2A mRNA的表达上调7d达峰值（P〈0．05）;而BDNF mRNA表达上调14d达峰值。VPA干预组NR2A mRNA在大鼠海马不同时间及部位（除1d的CA3区）的表达较模型组明显下调（P〈0．05）;BDNF mRNA在大鼠海马不同时间及部位（除28d的DG区）的表达较模型组明显下调（P〈0．05）。结论锂－匹罗卡品腹腔注射可诱导大鼠海马NR2A和BDNF mRNA的表达明显上调;NR2A mRNA表达的增强可能是诱导调控BDNF mRNA表达增强的重要机制之一,说明NMDA受体亚基NR2A可能成为抑制癫痫发作的新靶点。     

Positive correlation of skeletal muscle UCP3 mRNA levels with overweight in male,but not in female,rats

The objective of this study was to investigate the sex-dependent regulation of skeletal muscle uncoupling protein (UCP)3 mRNA expression in response to overweight and its relationship with serum levels of free fatty acids, leptin, and insulin. Two obesity models were used: rats made obese by feeding them with a cafeteria diet for 14 wk, and postcafeteria overweight rats fed a chow diet for 10 wk after consuming the cafeteria diet for 14 wk. The effects of 24-h fasting were studied in postcafeteria rats and their age-matched controls. The cafeteria rats ate a high-fat diet and attained an excess body weight that was higher in females (+59%) than in males (+39%). A trend to higher induction of abdominal muscle UCP3 mRNA in male rats than in females after cafeteria diet was apparent (+116% increase vs. +26% increase). Postcafeteria male but not female rats still showed the tendency to have increased UCP3 mRNA levels relative to their age-matched controls. A linear regression analysis showed a significant positive correlation of the UCP3 mRNA levels with overweight and with serum levels of leptin and insulin in males, but not in females, and no correlation with serum free fatty acid levels. A subsequent correlation analysis and a multiple linear regression analysis showed that overweight was the only parameter actually related to UCP3 mRNA levels in males. Fasting-induced upregulation of muscle UCP3 mRNA levels was higher in males (5- to 7-fold) than in females (3- to 4-fold). Our results point to the existence of sex-associated differences in the control of muscle UCP3 expression in response to overweight and fasting, with an impaired induction in female rats under both conditions. The correlation of abdominal muscle UCP3 mRNA expression with overweight in males could be related to their relative resistance to gain weight after chronic overeating of a cafeteria diet, by the purported role of UCP3 in the regulation of lipid utilization.     

艾芬地尔对异氟烷所致发育期海马神经元毒性的保护作用

目的:通过体外实验探讨艾芬地尔对异氟烷所致发育期海马神经元毒性的保护作用。方法:从出生一天的大鼠海马获取神经元并体外培养5天。这些神经元被随机分入4组,包括对照组(control组)、异氟醚组(Iso组)、艾芬地尔(Ifen组)和艾芬地尔+异氟烷组(Ifen+ISO组)。使用MTT法检测细胞活力及细胞损伤程度。使用TUNEL染色法检测细胞凋亡。使用Western blot法检测神经元中NMDA受体亚基NR2B和活化caspase-3的表达水平。结果:与对照组比较,在2.4%异氟烷暴露后1小时神经元的细胞活力显著下降(P0.05)。同时,在2.4%异氟烷暴露后神经元的凋亡指数也显著升高(P0.05)。Western blot结果显示,异氟烷暴露可显著升高神经元活化caspase-3和NR2B的表达水平(P0.05)。然而,使用NR2B拮抗剂艾芬地尔(20μM)不仅可显著减少异氟烷所致的NR2B表达水平增高,也可缓解异氟烷造成的神经元凋亡和细胞损伤(P0.01)。结论:异氟烷可导致发育期神经元NR2B表达水平增高,而使用NR2B受体拮抗剂艾芬地尔可有效抑制NR2B的表达水平从而减少异氟烷所致神经元毒性。     

Chronic blockade of N-methyl-D-aspartate receptors alters gamma-aminobutyric acid type A receptor peptide expression and function in the rat

Chronic in vivo or in vitro application of GABA(A) receptor agonists alters GABA(A) receptor peptide expression and function. Furthermore, chronic in vitro application of N-methyl-D-aspartate (NMDA) agonists and antagonists alters GABA(A) receptor function and mRNA expression. However, it is unknown if chronic in vivo blockade of NMDA receptors alters GABA(A) receptor function and peptide expression in brain. Male Sprague-Dawley rats were chronically administered the noncompetitive NMDA receptor antagonist MK-801 (0.40 mg/kg, twice daily) for 14 days. Chronic blockade of NMDA receptors significantly increased hippocampal GABA(A) receptor alpha4 and gamma2 subunit expression while significantly decreasing hippocampal GABA(A) receptor alpha2 and beta2/3 subunit expression. Hippocampal GABA(A) receptor alpha1 subunit peptide expression was not altered. In contrast, no significant alterations in GABA(A) receptor subunit expression were found in cerebral cortex. Chronic MK-801 administration also significantly decreased GABA(A) receptor-mediated hippocampal Cl- uptake, whereas no change was found in GABA(A) receptor-mediated cerebral cortical Cl- uptake. Finally, chronic MK-801 administration did not alter NMDA receptor NR1, NR2A, or NR2B subunit peptide expression in either the cerebral cortex or the hippocampus. These data demonstrate heterogeneous regulation of GABA(A) receptors by glutamatergic activity in rat hippocampus but not cerebral cortex, suggesting a new mechanism of GABA(A) receptor regulation in brain.     

Transient Global Ischemia Alters NMDA Receptor Expression in Rat Hippocampus: Correlation with Decreased Immunoreactive Protein Levels of the NR2A/2B Subunits, and an Altered NMDA Receptor Functionality

Abstract: We investigated the gene expression levels, the immunoreactive protein prevalence, and the functional activity of N -methyl- d -aspartate (NMDA) receptor complexes at early times after severe global ischemia challenge in rats. The mRNA expression levels for the NR2A and NR2B subunits of NMDA receptors changed to different degrees within different subregions of the hippocampus after reperfusion with respect to sham-operated control. No significant change in expression was observed in the vulnerable CA1 subfield at or before 6 h after challenge for either receptor subunit, although changes in expression in other hippocampal subfields were observed. At 12 and 24 h after challenge, significant decreases in expression for both subunits were found in the vulnerable CA1 subfield, as well as in other hippocampal regions. At the protein level, a significant decrease in the amount of NR2A/NR2B immunoreactivity in the total hippocampus was observed at both 6 and 24 h after reperfusion compared with sham control. Electrophysiological assessment of single-channel NMDA receptor activity in the CA1 subfield indicates that the main conductance state of NMDA receptor channels is maintained 6 h after challenge, although by 18–24 h after challenge, this main conductance state is rarely observed. The NMDA receptor component of the excitatory postsynaptic field potential was found to be significantly diminished from sham control 24 h after challenge, such that only ∼10% of the sham response remained, but was not significantly altered from sham control at 6 h after challenge. These results indicate that decreases in the expression levels, the immunoreactive protein prevalence, and that alterations in the functionality of NMDA receptors occur in the hippocampus at early times after severe transient global ischemia.     

Exposure to social defeat stress in adolescence improves the working memory and anxiety-like behavior of adult female rats with intrauterine growth restriction,independently of hippocampal neurogenesis

Intrauterine growth restriction (IUGR) is a risk factor for memory impairment and emotional disturbance during growth and adulthood. However, this risk might be modulated by environmental factors during development. Here we examined whether exposing adolescent male and female rats with thromboxane A2-induced IUGR to social defeat stress (SDS) affected their working memory and anxiety-like behavior in adulthood. We also used BrdU staining to investigate hippocampal cellular proliferation and BrdU and NeuN double staining to investigate neural differentiation in female IUGR rats. In the absence of adolescent stress, IUGR female rats, but not male rats, scored significantly lower in the T-maze test of working memory and exhibited higher anxiety-like behavior in the elevated-plus maze test compared with controls. Adolescent exposure to SDS abolished these behavioral impairments in IUGR females. In the absence of adolescent stress, hippocampal cellular proliferation was significantly higher in IUGR females than in non-IUGR female controls and was not influenced by adolescent exposure to SDS. Hippocampal neural differentiation was equivalent in non-stressed control and IUGR females. Neural differentiation was significantly increased by adolescent exposure to SDS in controls but not in IUGR females. There was no significant difference in the serum corticosterone concentrations between non-stressed control and IUGR females; however, adolescent exposure to SDS significantly increased serum corticosterone concentration in control females but not in IUGR females. These results demonstrate that adolescent exposure to SDS improves behavioral impairment independent of hippocampal neurogenesis in adult rats with IUGR.     

Distinctive stress effects on learning during puberty

Puberty is a time of significant change in preparation for adulthood. Here, we examined how stressful experience affects cognitive and related hormonal responses in male and female rats prior to, during and after puberty. Groups were exposed to an acute stressor of brief periodic tailshocks and tested 24 h later in an associative memory task of trace eyeblink conditioning. Exposure to the stressor did not alter conditioning in males or females prior to puberty but enhanced conditioning in both males and females during puberty. The enhancement occurred in pubescent females irrespective of the estrous cycle. In adulthood, sex differences in trace conditioning and the response to stress emerged: females outperformed males under unstressed conditions, but after stressor exposure, trace conditioning in females was impaired whereas that in males was enhanced. These differences were not related to changes in gross motor activity or other nonspecific measures of performance. The effects of acute stress on corticosterone, estradiol, progesterone, and testosterone were also measured. Stressor exposure increased the concentration of corticosterone in all age groups, although sex differences were only evident in adults. All reproductive hormones except estradiol increased with age in a predictable and sex dependent fashion and none were affected by stressor exposure. Estradiol decreased in male rats across age, and remained stable for female rats. Together, these data indicate that males and female respond similarly to learning opportunities and stressful experience before and during puberty; it is in adulthood that sex differences and the opposite responses to stress arise.     

Regulation of N-methyl-D-aspartate receptor subunit expression in the fetal guinea pig brain

N-methyl-d-aspartate receptors (NMDARs) are critical for neuronal maturation and synaptic formation as well as for the onset of long-term potentiation, a process critical to learning and memory in postnatal life. In the current study, we demonstrated that NMDAR subunits undergo spatial, temporal, and sex-specific regulation. During development, we observed increasing NR1 and NR2A expression at the same time as levels of NR2B subunits decreased in the hippocampus and cortex in the fetal guinea pig. We have also shown that glucocorticoids can modulate fetal NMDAR subunit expression in a sex-specific fashion. This is clinically important because synthetic glucocorticoids are administered to pregnant women at risk of preterm labor. Repeated exposure to exogenous glucocorticoids caused a dose-dependent decrease in NR1 mRNA levels and increased NR2A mRNA expression in the female hippocampus at Gestational Day 62. There are significant changes in NMDAR subunit expression in late gestation. It is possible that these alter NMDA-dependent signaling at this time. Prenatal exposure to exogenous glucocorticoids modifies the trajectory of NMDAR subunit expression in females but not in males.     

围产期食物限制对子代成年大鼠海马CA1区突触可塑性的影响

围产期食物限制导致子代大鼠学习和记忆能力等的神经生物学变化,但其机制并不清楚。将成年Wistar雌性大鼠与雄性大鼠同笼,受孕后随机分为对照组 (n=9) 和食物限制组 (n=8) 。对照组母鼠在妊娠期和哺乳期自由进食和饮水,食物限制组母鼠从妊娠的第7天到子代大鼠出生后21天进行食物限制,食物限制量为对照组大鼠的50%。子代雄性大鼠成年后,通过Morris 水迷宫测试空间学习和记忆能力。之后,在海马CA1区在体记录场兴奋性突触后电位 (field excitatory postsynaptic potential,fEPSP),并采用免疫组织化学方法观察海马CA1区神经元型一氧化氮合酶 (nNOS) 阳性细胞密度的变化。结果表明,围产期食物限制降低了子代大鼠出生后第1、7、10、14和21天的体重,并减弱了成年子代大鼠的学习和记忆能力,海马CA1区fEPSP的斜率和nNOS阳性细胞的密度也明显降低。结果提示,围产期食物限制可能通过抑制NO的产生降低了海马突触可塑性,从而影响了子代大鼠的学习和记忆能力。     

miR-103a对癫痫大鼠海马组织星形胶质细胞活化的影响

为了考察miR-103a对癫痫大鼠海马组织星形胶质细胞活化的影响。本研究通过腹腔注射氯化锂和毛果芸香碱诱导癫痫大鼠模型,对大鼠脑室内注射miR-103a抑制剂来敲低miR-103a的表达;采用免疫组织化学染色检测大鼠海马组织中胶质纤维酸性蛋白(GFAP)的阳性表达;采用RT-qPCR和Western blotting方法检测大鼠海马组织中miR-103a、脑源性神经营养因子(BDNF)、GFAP、TNF-α和IL-6的m RNA和蛋白表达;苏木精-伊红(HE)染色评价海马组织病变程度;Nissl染色检测神经元存活情况;TUNEL染色检测神经元的凋亡。结果显示,癫痫大鼠海马组织中miR-103a被上调。下调miR-103a抑制癫痫大鼠海马组织中GFAP的mRNA和蛋白表达,且抑制癫痫大鼠海马神经元的病理损伤,但能促进癫痫大鼠海马神经元的存活并抑制其凋亡。此外,下调miR-103a还抑制癫痫大鼠海马组织中IL-6和TNF-α的表达,并促进癫痫大鼠海马组织中BDNF的表达。本研究表明,靶向沉默miR-103a可以抑制癫痫大鼠海马组织中星形胶质细胞的活化并改善神经元的病理损伤。