Transmitter amino acid levels in rat brain regions after amygdala-kindling or chronic electrode implantation without kindling: Evidence for a pro-kindling effect of prolonged electrode implantation

Kindling is a chronic model of epilepsy characterized by a progressive increase in response to the same regularly applied stimulus. The biological basis of the kindling phenomenon requires to be determined, but several studies indicate that alterations in amino acidergic neurotransmission may be involved. In the present experiments, levels of glutamate, aspartate, GABA, glycine, and taurine were determined in 12 brain regions by HPLC in 3 groups of animals: (a) a group which was kindled via electrical stimulation of intraamygdala electrodes and was sacrificed 36 days after the last fully kindled seizure for neurochemical determinations; (b) a group of implanted but nonstimulated rats (surgical control group) in which neurochemical measurements were done at the same time after electrode implantation as the kindled group, and (c) a group of non-implanted, naive control rats. Compared to surgical controls, kindling induced a significant reduction of glutamate, GABA, and taurine in the brain stem (pons/medulla), whereas no differences between both groups were found in any of the other regions. However, both electrode-implanted groups differed significantly from non-implanted naive rats in several regions, indicating that electrode-implantation per se induced long-lasting alterations in transmitter amino acids. The most striking difference to naive controls was an increase of glycine levels in several regions in which this amino acid is known to potentiate glutamatergic transmission. In order to examine the functional consequences of prolonged electrode implantation, seizure thresholds were determined in groups of rats with short and prolonged electrode implantation. Data from these experiments indicated that prolonged electrode implantation per se induces pro-kindling effects, i.e. a dramatic decrease of seizure threshold. The data of this study thus demonstrate that the choice of adequate controls is critical in neurochemical and functional studies on the kindling phenomenon.     

Focus: The Science of Stress: Potential Societal and Cultural Implications of Transgenerational Epigenetic Methylation of Trauma and PTSD: Pathology or Resilience?

Psychological trauma is unique in that it is an environmental event that could induce biological changes and post-traumatic stress disorder (PTSD), depression, or other mood disorders in some patients. On the other hand, there may be no psychopathology (in most cases), or even sometimes post-traumatic growth and resilience. According to the DSM-5, trauma is a prerequisite for PTSD and traumatic stress disorder, but not for depressive episodes or mood disorders, or other psychiatric conditions. This paper brings attention to the preliminary literature on transgenerational inheritance due to trauma exposure and its societal and cultural implications. There is accumulating evidence that exposure to trauma can be passed transgenerationally through epigenetic inheritance leading to changes in gene expression and possible disorders or resilience. The effects of resilience from transgenerational inheritance have not been studied, but should be, for a full understanding not only of the disease risk across generations, but also of its social and cultural implications. The epigenetic pathologic effects across generations also need further studies, as the current research is preliminary; larger replications are needed for definitive and more complete understanding. I present here a glimpse of where we are, a vision of where we should go in terms of future research direction for disease risk transmission, and recommend studies of resilience and post-traumatic growth across generations, as well as other studies related to the societal implications at the population level.     

电刺激右后背海马诱导双侧前背海马网络癫痫

目的 :急性强直电刺激右侧后背HPC诱导双侧HPC癫痫电网络形成的细胞机制。方法 :强直电刺激 (6 0Hz,2s,0 .4～ 0 .6mA)大鼠右后背HPCCA1基树突区 ,每隔 10min刺激一次 ,施加 10个刺激串。结果 :①分别抑制双侧CA1神经元单位放电频率 ,对侧的抑制效应更明显 (对侧 :6 2 .94 %± 3.6 8% ;同侧 :36 .6 1%± 3.14 % ,P <0 .0 1) ,出现抑制后爆发式放电。随着刺激串数的增加 ,抑制作用逐渐减弱。②同步原发性网络和单位后放电 ,以同侧CA1多见 (P<0 .0 1)。③ 90Hz或 12 0Hz原发性或继发性网络后放电仅仅累及同侧CA1。④对侧CA3基树突区网络与下托神经元单位放电出现同步继发性后放电 ,反复发作 ,持续约数小时。结论 :电刺激诱导的对侧HPC抑制后爆发式放电和长时程、反复发作的网络与单个神经元同步继发性后放电可能是跨半球癫痫网络形成的重要表现形式。     

红藻氨酸癫痫大鼠海马GFAP基因调控蛋白表达的变化

目的和方法：用Southwestern印迹从红藻氨酸（KA）癫痫大鼠海马结构中筛选调控胶质原纤维酸性蛋白（GFAP）基因表达的DNA结合蛋白;并观察其在海马内表达变化的规律,旨在从基因调控水平深入探讨癫痫反复发作形成的神经病理学机制。结果：Southwestern印迹的实验显示海马结构内有两种调控GFAP基因表达的序列特异的DNA结合蛋白,分子量分别为39kDa和35.5kDa;KA后1d,两种调控蛋白的表达即开始增加,5－7d时表达显著增加,3周时表达最多,3个月时表达仍很高。结论：KA通过上调调控GFAP基因表达的转录因子,使海马GFAP过量表达,提示该转录调控因子很可能参与一次KA后癫痫反复发作的形成。     

Allozyme analysis of cryptic species in the Asplenium niduscomplex from West Java,Indonesia

In various fern species, a large amount of rbcL sequence variation has been reported, and it is possible that these species contain several reproductively isolated cryptic species. In our previous study on Asplenium nidus L., it was suggested that the plants growing in Mt. Halimun National Park, West Java, Indonesia, consist of several cryptic species based on the results of crossing experiments among rbcL sequence types. In this study, we examined allozyme polymorphisms of five rbcL sequence types found in West Java in order to test the hypothesis that the assemblages of A. nidus delimited based on the rbcL sequences are separate Mendelian populations and gene flow is disrupted by reproductive isolation from one another. The calculated fixation indices suggested that the individuals in each rbcL type are randomly crossing at least in the investigated localities. Nevertheless, these rbcL-based assemblages were genetically differentiated in allozymes that are encoded in their nuclear genomes, and it is also suggested that gene flow is disrupted even between sympatrically distributed pairs of rbcL sequence types. Therefore, our findings support the view that the five rbcL sequence types in West Java are potential cryptic species. Electronic Publication     

Importance of drought on the distribution of the birds nest fern,Asplenium nidus,in the canopy of a lowland tropical rainforest in north‐eastern Australia

Abstract The birds nest fern, Asplenium nidus, contributes greatly to the epiphytic biomass in the canopies of both south‐east Asia and tropical north Queensland rainforests. It is generally believed that their abundance and their capacity to store water is an important feature for habitat fragmentation in the canopy. We investigated the microclimate of A. nidus and the effects of severe drought periods on the A. nidus population over a 20‐year period, hypothesizing that water availability is the most important factor controlling the population under drought conditions. One of two neighbouring A. nidus plants of the same size and age was irrigated artificially before, during and after a significant dry period in 2000. By monitoring the microclimate within and around both ferns we were able to estimate that four continuous weeks of rainless weather completely dried out the accumulated humus of the non‐irrigated A. nidus fern. Prolonged dry periods were shown to kill the roots of A. nidus, which attach the fern to the bark and eventually the affected A. nidus on verticals stems fell to the ground. Periods longer than 8 weeks may even kill adult plants sitting in more protected branch forks. Analysis of the whole A. nidus population within the 1‐ha Canopy Crane plot and the determination of the morphological age of all plants enabled an evaluation of the historical development of the population. The oldest plant originated in 1985, just 1 year after the longest recorded drought for the site. We suspect that the 1984 drought killed every A. nidus plant within the study plot. Years with low recruitment coincide with years with long drought periods.     

Expression and Localization of Type II Diacylglycerol Kinase Isozymes δ and η in the Developing Mouse Brain

The functions of type II diacylglycerol kinase (DGK) δ and -η in the brain are still unclear. As a first step, we investigated the spatial and temporal expression of DGKδ and -η in the brains of mice. DGKδ2, but not DGKδ1, was highly expressed in layers II–VI of the cerebral cortex; CA–CA3 regions and dentate gyrus of hippocampus; mitral cell, glomerular and granule cell layers of the olfactory bulb; and the granule cell layer in the cerebellum in 1- to 32-week-old mice. DGKδ2 was expressed just after birth, and its expression levels dramatically increased from weeks 1 to 4. A substantial amount of DGKη (η1/η2) was detected in layers II–VI of the cerebral cortex, CA1 and CA2 regions and dentate gyrus of the hippocampus, mitral cell and glomerular layers of the olfactory bulb, and Purkinje cells in the cerebellum of 1- to 32-week-old mice. DGKη2 expression reached maximum levels at P5 and decreased by 4 weeks, whereas DGKη1 increased over the same time frame. These results indicate that the expression patterns of DGK isozymes differ from each other and also from other isozymes, and this suggests that DGKδ and -η play distinct and specific roles in the brain.     

Traumatic brain injury

There is an increasing incidence of military traumatic brain injury (TBI), and similar injuries are seen in civilians in war zones or terrorist incidents. Indeed, blast-induced mild TBI has been referred to as the signature injury of the conflicts in Iraq and Afghanistan. Assessment involves schemes that are common in civilian practice but, in common with civilian TBI, takes little account of information available from modern imaging (particularly diffusion tensor magnetic resonance imaging) and emerging biomarkers. The efficient logistics of clinical care delivery in the field may have a role in optimizing outcome. Clinical care has much in common with civilian TBI, but intracranial pressure monitoring is not always available, and protocols need to be modified to take account of this. In addition, severe early oedema has led to increasing use of decompressive craniectomy, and blast TBI may be associated with a higher incidence of vasospasm and pseudoaneurysm formation. Visual and/or auditory deficits are common, and there is a significant risk of post-traumatic epilepsy. TBI is rarely an isolated finding in this setting, and persistent post-concussive symptoms are commonly associated with post-traumatic stress disorder and chronic pain, a constellation of findings that has been called the polytrauma clinical triad.     

Soral crypsis: protective mimicry of a coccid on an Indian fern

Herbivory with crypsis is not well documented in ferns. The present record of cryptic coloration of coccid Saissetia filicum Boisduval (Homoptera: Coccidae) to the sori of a fern species Asplenium nidus L. (Aspleniaceae) is unique. Predatory beetles (Jauravia sp., Coleoptera: Coccinellidae) that feed on the coccids, are suggested to be selective pressure for the development of the present homopteran soral crypsis. A higher rate of effective predation is noticed in the vegetative leaves than the fertile leaves. Aggressive ants were found harvesting honeydew secretions from the coccids and defending the trophobionts as well as the host fern from their natural enemies. In addition, a possible three-way mutualistic relationship among the coccids, its host fern and the tending ant is suggested. Differential numbers of coccids on vegetative and fertile leaves is correlated with their phenol content and degree of predation by beetles. Such coloration mimicry by the coccids may enable them to obtain the necessary blend of sorus of the host fern needed to evade beetle detection and attack.