Early eyelid opening enhances spontaneous alternation and accelerates the development of perforant path synaptic strength in the hippocampus of juvenile rats

Development of the hippocampus is not entirely preprogrammed; its structure and function are sensitive to postnatal experience. For instance, neonatal handling/exposure to novelty and peripubertal environmental enrichment enhance hippocampal function and related memory abilities. However, these complex environmental manipulations make it difficult to deduce the primary stimuli that drive more rapid hippocampal maturation, and few experiments have studied the neural mechanisms that support the behavioral modifications. To address these issues, I performed early eyelid opening in rat pups and examined developmental alterations in exploration of a Y-maze and in synaptic transmission measured in hippocampal slices. Early eyelid opening accelerated development of spontaneous alternation. Additionally, early eyelid opening promoted more rapid remodeling of afferent input to the dentate gyrus and area CA1 as well as earlier maturation of perforant path synaptic physiology. These findings implicate visual input as an extrinsic factor that drives hippocampal development and the emergence of hippocampal-dependent behavior.     

Role of Kir2.2 in hypercapnic ventilatory response during postnatal development of mouse

In order to determine the role of Kir2.2 in the hypercapnic ventilatory response (HCVR) during postnatal development, we measured the response of the Kir2.2-knockout (Kir2.2-/-) mouse in an unanesthetized unrestrained state by means of pressure plethysmography on postnatal days 9-10, 14-15 and 18, and compared the response with that in its wild counterpart, the FVB mouse. We also examined developmental changes in m-RNA expression of Kir2.2 in the brainstem of the FVB mouse using quantitative real-time PCR assay. Kir2.2-/- exhibited a smaller increase in tidal volume and minute ventilation volume than the FVB mouse in response to hypercapnic challenge on days 14-15. Meanwhile, the FVB mouse showed a transient increase in m-RNA expression of Kir2.2 in the brainstem on days 14-15. These findings suggest that Kir2.2 in the brainstem plays a transient role in HCVR, possibly through central ventilatory chemosensitivity, during postnatal development.     

Effect of electrical cutaneous stimulation on the level of succinate dehydrogenase activation and changes in glutamatergic synaptic transmission in response to sensory stimulation

It is shown that the rise of succinate dehydrogenase activity in the hippocampus depends on the number of sensory stimuli presented before decapitation, which correlates with changes in the efficiency of glutamatergic synaptic transmission in hippocampal sections from the same animal. Electrocutaneous stimulation potentiates the activation of succinate dehydrogenase induced by sensory stimulation probably due to enhanced glutamate release. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 123, No. 4, pp. 404–407, April, 1997     

小鼠脊髓神经元内脑啡肽与1型囊泡膜谷氨酸转运体的共存

目的:以PPE-GFP转基因小鼠为研究工具,观察绿色荧光蛋白(GFP)阳性的脑啡肽(ENK)能神经元与1型囊泡膜谷氨酸转运体(VGLUT1)在脊髓的分布及共存情况。方法:利用免疫组织化学和原位杂交双标染色的方法。结果:GFP标记的ENK能神经元主要位于脊髓背角,在I-ⅡI层最为密集,背角深层内侧部及中央管周围呈中等密度分布,散在分布于前角。VGLUT1 mRNA阳性细胞广泛分布在脊髓各层。GFP/VGLUT1双标细胞主要分布在脊髓背角,I-ⅡI层双标细胞占GFP阳性细胞的22.95±1.10%,占VGLUT1阳性细胞的27.91±2.42%;IV-VI层中21.49±4.99%GFP阳性细胞表达VGLUT1,10.35±2.81%VGLUT1阳性细胞表达GFP;前角双标细胞占VGLUT1阳性细胞的1.07±0.37%,占GFP阳性细胞的32.08±13.15%。结论:双标结果表明脊髓内部分ENK能神经元表达1型囊泡膜谷氨酸转运体,推测ENK能神经元可能通过调控谷氨酸的释放发挥感觉信息调控作用。     

Activity-dependent release of adenosine inhibits the glutamatergic synaptic transmission and plasticity in the hypothalamic hypocretin/orexin neurons

The hypocretin (orexin) neurons in the lateral hypothalamus play a crucial role in the promotion of arousal. Adenosine, an endogenous sleep-promoting factor, modulates both neuronal excitatory and synaptic transmission in the CNS. In this study, the involvement of endogenous adenosine in the regulation of excitatory glutamatergic synaptic transmission to hypocretin neurons was investigated in the hypothalamic slices from transgenic mice by using different frequencies of stimulation. A train of low-frequency stimulation (0.033, 1 Hz) had no effect on the amplitude of evoked excitatory postsynaptic currents (evEPSCs) in hypocretin neurons. Blockade of adenosine A1 receptors with selective A1 receptor antagonist 8-cyclopentyltheophylline (CPT), the amplitude of evEPSCs did not change during 0.033 and 1 Hz stimuli. When the frequency of stimulation was increased upto 2 Hz, a time-dependent depression of amplitude was recorded in hypocretin neurons. Administration of CPT caused no significant change in depressed synaptic response induced by 2 Hz stimulus. While depression induced by 10 and 100 Hz stimuli was partially inhibited by the CPT but not by the selective A2 receptor antagonist 3,7-dimethyl-1-(2-propynyl)xanthine. Further findings have demonstrated that high-frequency stimulation could induce long-term potentiation (LTP) of glutamatergic synaptic transmission to hypocretin neurons in acute hypothalamic slices. The experiments with CPT suggested that A1 receptor antagonist could facilitate the induction of LTP, indicating that endogenous adenosine, acting through A1 receptors, may suppress the induction of LTP of excitatory synaptic transmission to hypocretin neurons. These results suggest that in the hypothalamus, endogenous adenosine will be released into extracellular space in an activity-dependent manner inhibiting both basal excitatory synaptic transmission and LTP in hypocretin neurons via A1 receptors. Our data provide further support for the notion that hypocretin neurons in the lateral hypothalamus may be another important target involved in the endogenous adenosine modulating the sleep and wakefulness cycle in the mammalian CNS.     

CatSper gene expression in postnatal development of mouse testis and in subfertile men with deficient sperm motility

BACKGROUND: The search for Ca2+ channels residing in sperm has led to the recent cloning and characterization of a novel gene, named CatSper, which codes for a unique Ca2+ channel expressed exclusively in the testis. It plays an essential role in sperm motility, penetration into the oocyte, and ultimately in male fertility. In this study, we assessed the temporal profile of CatSper gene expression during mouse testis development and performed a semi-quantitative evaluation of expression levels in a group of subfertile men which lack sperm motility. METHODS: A small piece of testicular tissue obtained by either multi-site testicular biopsy or orchidectomy was used for semi-quantitative RT-PCR of CatSper and beta2-microglobulin (beta2m, as an internal control) genes. RESULTS: Our results reveal that: (i) the expression of mouse CatSper is developmentally regulated with a direct correlation between CatSper expression and mouse sexual maturation. CatSper gene expression is first detected at 3 weeks of age and coincides with the appearance of round spermatids in the developing mouse testis. (ii) There is a significant reduction in the level of CatSper gene expression (up to 3.5-fold difference) among patients which lack sperm motility as compared with patients whose infertility cannot be ascribed to a deficiency in motility (used as a control). CONCLUSIONS: The data obtained in this study support a potential role for CatSper in sperm motility and fertility in mouse and human. CatSper is therefore implicated as a potential target to explore the molecular mechanisms of male infertility.     

Regulatory role of sorting nexin 5 in protein stability and vesicular targeting of vesicular acetylcholine transporter to synaptic vesicle-like vesicles in PC12 cells

Accurate targeting of vesicular acetylcholine transporter (VAChT) to synaptic vesicles (SVs) is indispensable for efficient cholinergic transmission. Previous studies have suggested that the dileucine motif within the C-terminus of the transporter is sufficient for its targeting to SVs. However, the cytosolic machinery underlying specific regulation of VAChT trafficking and targeting to SVs is still unclear. Here we used the C-terminus of VAChT as a bait in a yeast two-hybrid screen to identify sorting nexin 5 (SNX5) as its novel interacting protein. SNX5 was detected in the SVs enriched LP2 subcellular fraction of rat brain homogenate and showed strong colocalization with VAChT in both brain sections and PC12 cells. Binding assays suggested that the C-terminal domain of VAChT can interact with both BAR and PX domain of SNX5. Depletion of SNX5 enhanced the degradation of VAChT and the process was mediated through the lysosomal pathway. More importantly, we found that, in PC12 cells, the depletion of SNX5 expression significantly decreased the synaptic vesicle-like vesicles (SVLVs) localization of VAChT. Therefore, the results suggest that SNX5 is a novel regulator for both stability and SV targeting of VAChT.     

Expression profile of PRAF2 in the human brain and enrichment in synaptic vesicles

PRA1 domain family, member 2 (PRAF2) is a novel 19-kDa protein with a prenylated Rab acceptor 1 (PRA1) motif and four transmembrane domains. Our previous studies revealed that PRAF2 is highly expressed in the brain and serves as a candidate prognostic marker in neuroblastoma (NB). PRAF2 is related to proteins PRAF1 (PRA1, prenylin, Yip3) and PRAF3 (GTRAP3-18, JWA, Arl6-IP5), both of which are enriched in the brain and implicated in cellular transport and endo/exocytic vesicle trafficking. However, the function for PRAF2 remains unknown. In this study, we analyzed the distribution and localization of PRAF2 in the mature human brain using two new antibodies specific for the protein. Analysis by immunohistochemistry revealed that in the human cerebellum, the PRAF2 protein was strongly expressed in Purkinje cells and, more moderately, in cells of the molecular and the granular layers. In the cerebral cortex, hippocampus, and lateral ventricles, PRAF2 protein was detected in neuronal cells, but not in non-neuronal cells. Intriguingly, immunoblot analysis revealed that PRAF2 is enriched in synaptic vesicles (SVs) prepared from rat brains. The expression of PRAF2 in specific regions of the brain including SVs suggest an important physiological function for this novel protein, possibly by participating in multiple aspects of SV maturation, transport, and signal transmission.     

Insertion mutation at the C-terminus of the serotonin transporter disrupts brain serotonin function and emotion-related behaviors in mice

The 5-hydroxytryptamine transporter (5-HTT) regulates 5-hydroxytryptamine (5-HT) neurotransmission by removing 5-HT from the synaptic cleft. Emerging evidence from clinical and genetic studies implicates the 5-HTT in various neuropsychiatric conditions, including anxiety and depression. Here we report that a 5-HTT null mutant mouse line was generated by gene trapping that disrupted the sequence encoding the C-terminus of 5-HTT. This mutation resulted in significant reduction of 5-HTT mRNA and loss of 5-HTT protein. Brain levels of 5-HT and its major metabolite, 5-hydroxyindoleacetic acid, were markedly decreased in C-terminus 5-HTT -/- mice, while 5-HT uptake or 5-HT content in platelets was absent. Behavioral phenotyping showed that C-terminus 5-HTT -/- mice were normal on a screen for gross behavioral, neurological, and sensory functions. In the tail suspension test for depression-related behavior, C-terminus 5-HTT -/- mice showed increased immobility relative to their +/+ controls. By comparison, a previously generated line of 5-HTT -/- mice lacking exon 2, encoding the N-terminus of the 5-HTT, showed abnormally high immobility in response to repeated, but not acute, exposure to the tail suspension test. In a novel, brightly-lit open field, both C-terminus 5-HTT -/- mice and N-terminus 5-HTT -/- mice displayed decreased center time and reduced locomotor activity compared with their +/+ controls. Both mutant lines buried significantly fewer marbles than their +/+ controls in the marble burying test. These findings further demonstrate the neurobiological functions of the 5-HTT and add to a growing literature linking genetic variation in 5-HTT function with emotional abnormalities.     

Genetic variation in the development of mouse brain and behavior: evidence from the middle postnatal period.

Six inbred strains and 3 F2 hybrid crosses of mice were assessed for developmental status at 32 days after conception (about 13 days after birth). Phenotypes measured included body weight, brain weight, maturity of 14 reflexive behaviors, myelination of 80 fiber tracts, and thickness of the external granular layer of the cerebellum. All measures of brain and behavior showed a similar pattern of results: hybrids were generally more advanced than either of their inbred parent strains; differences among inbred strains were large, but differences among hybrid crosses were quite small. Acceleration of F2 mice compared to their homozygous relatives ranged from .5 to 2.4 days mean difference. Developmental ages of inbred litters ranged from 28.7 to 32.2 days, whereas hybrid litters ranged from 31.5 to 32.7 days.     

小鼠脑中Zn元素和ZnT3 mRNA表达的研究

目的：研究ZnT3 mRNA的表达与Zn等金属元素在脑中精细分布的相互作用和功能。方法:使用同步辐射X射线荧光法（SRXRF）测定小鼠全脑和脑切片中Zn等金属元素分布，同时使用反转录多聚酶链式反应（RT-PCR）检测小鼠各组织中的ZnT3 mRNA的表达量。结果:脑中Zn元素不是均匀分布的，主要分布在皮层、海马和齿状回部位。大脑皮层、海马和睾丸中的ZnT3 mRNA有较高丰度，而其它组织中未检出ZnT3 mRNA 。结论：ZnT3能促进胞浆内Zn富集于囊泡中，通过介导胞浆锌的跨膜转运过程，构造囊泡“锌池”。     

The expression of twisted gastrulation in postnatal mouse brain and functional implications

Twisted gastrulation (TWSG1), an extracellular regulator of bone morphogenetic protein (BMP) signaling, is critical for embryonic brain development. Mice deficient in TWSG1 have abnormal forebrain development manifesting as holoprosencephaly. The expression and potential roles of TWSG1 in postnatal brain development are less well understood. We show that Twsg1 is expressed in the adult mouse brain in the choroid plexus (CP), hippocampus, and other regions, with the strongest expression observed in CP. TWSG1 was also detected in a human fetal brain at mid-gestation, with highest levels in the epithelium of CP. Bmp1, Bmp2, Bmp4–Bmp7 as well as BmprIA and BmprII, but not BmprIB, were expressed in CP. BMP antagonists Chordin (Chrd) and Noggin were not detected in CP, however Chrd-like 1 and brain-specific Chrd-like (Brorin) were expressed. Electrophysiological study of synaptic plasticity revealed normal paired-pulse facilitation and long-term potentiation in the CA1 region of hippocampus in Twsg1^−/− mice. Among the homozygous mutants that survive beyond the first 2 weeks, the prevalence of hydrocephalus was 4.3%, compared to 1.5% in a wild type colony (P=0.0133) between 3 and 10 weeks of life. We detected a high level of BMP signaling in CP in wild type adult mice that was 17-fold higher than in the hippocampus (P=0.005). In contrast, transforming growth factor beta (TGFβ) signaling was predominant in the hippocampus. Both BMP signaling and the expression of BMP downstream targets Msx1 and Msx2 were reduced in CP in Twsg1^−/− mice. In summary, we show that Twsg1 is expressed in the adult mouse and human fetal CP. We also show that BMP is a branch of TGFβ superfamily that is dominant in CP. This presents an interesting avenue for future research in light of the novel roles of CP in neural progenitor differentiation and neuronal repair, especially since TWSG1 appears to be the main regulator of BMP present in CP.     

Inhibition of active H+ transport by local anesthetics and barbiturates in membranes of brain synaptic vesicles

Laboratory of Biochemistry, Research Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR G. N. Kryzhanovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 8, pp. 185–188 August, 1989.     

大鼠脊髓内囊泡膜谷氨酸转运体1和囊泡膜谷氨酸转运体2阳性纤维和终末在生后发育中的分布和表达变化

目的 探讨囊泡膜谷氨酸转运体1（VGLUT1）和VGLUT2阳性纤维和终末在生后第0天（P0）至第22天（P22）大鼠脊髓内的分布情况和表达变化。 方法 对生后发育P0～P22大鼠的颈膨大和腰膨大部位,进行VGLUT1和VGLUT2免疫组织化学染色。 结果 P0～P22大鼠颈膨大和腰膨大脊髓内均可观察到VGLUT1和VGLUT2阳性纤维和终末,但未观察到胞体样结构。VGLUT1和VGLUT2阳性纤维和终末的分布呈现明显的互补分布,尤其是以脊髓后角更加明显。其中,VGLUT1阳性纤维和终末在P0主要见于颈膨大和腰膨大脊髓后角Ⅲ～Ⅴ层,中间部和前角很微弱。脊髓发育至P3,不仅Ⅲ~Ⅴ层VGLUT1的表达进一步增强,且向外侧部扩展,并在后角基底部Ⅵ层和前角的外侧部（Ⅸ层）也可观察到较强的VGLUT1阳性纤维,呈现一条明显由背内向腹外的带状分布趋势。P7时此带状分布更加明显,并随着发育逐渐向内、外扩展,至P22时已广泛分布于除Ⅱ层之外的整个脊髓。而VGLUT2阳性纤维和终末在P0时即密集出现于脊髓后角Ⅰ～Ⅱ层以及前角的外侧边缘区域;之后随着发育,VGLUT2阳性纤维和终末的分布模式并未发生明显改变,但其密度逐渐有所增加,特别是Ⅰ～Ⅱ层内VGLUT2阳性产物的表达尤为明显。另外,在脊髓白质后索内可见VGLUT1阳性皮质脊髓后束纤维由颈髓（P3）逐渐下降至腰髓（P7）的发育过程。 结论 VGLUT1和VGLUT2阳性纤维和终末在脊髓发育过程中呈现明显不同,且表现出互补分布的特点,这对于进一步理解VGLUT1和VGLUT2在脊髓生后发育过程中不同功能特点可能有意义。     

Localization of CD226 in the mouse hippocampus and cerebellum during adulthood and postnatal development

CD226, a member of cell adhesion molecules, has been widely studied in the immune system; however, its expression in the CNS remains unknown. In our present study, we detected CD226 mRNA and protein in the mouse hippocampus and cerebellum by RT-PCR and Western blotting, respectively. Immunohistochemical studies found that CD226 is primarily located in the hilus of the dentate gyrus and stratum lucidum aligned along the pyramidal cells in the hippocampal CA3 area, the interspaces of granular cells and the somata of the Purkinje cells in the cerebellar cortex during adulthood. Double-staining results revealed that CD226 co-localized well with synaptic marker proteins including synaptophysin, syntaxin and PSD-95. During postnatal development, CD226 could not be detected at its adult locations until postnatal day 12; however, it was temporally expressed in the somata of neighboring or distant nuclei associated with its adult location. These results showed the diverse localization of CD226 in the mouse hippocampus and cerebellum for the first time and suggested its potential role in the CNS.     

出生前后胆碱乙酰转移酶在大鼠脑内定位的研究

为探讨大鼠胚胎及生后发育期间脑内胆碱乙酰转移酶(choline acetyltransferase,ChAT)的变化规律,本研究采用免疫组织化学方法,观察了胚胎和生后大鼠脑内ChAT样(ChAT-like immunoreactive,ChAT-LI)神经元表达的数量和灰度值。结果显示:ChAT-LI产物主要表达在细胞体、纤维及其末梢。ChAT-LI神经元最先在胚胎第12d(embryonic day12,E12),出现于端脑;E14时可见于隔核和中缝核;E16时内嗅区出现ChAT-LI神经元;E18时出现于视前区节细胞层;E20时,海马内部可见部分ChAT-LI纤维;生后第0d(postnatal day0,P0),少量带有生长锥的ChAT-LI纤维出现于海马;P5时,海马内出现ChAT-LI神经元,且ChAT-LI纤维进一步增加;P10时,海马、内嗅区和穹隆等结构中都可见ChAT-LI神经元胞体及纤维。上述结果提示:胆碱能神经元在出生前后的大鼠脑内,尤其是在海马记忆回路的发育过程中存在一定的变化规律,它们可能是学习记忆等功能的结构基础。     

Expression of Serotonin Transporter Gene and Startle Response in Rats with Genetically Determined Fear-Induced Aggression

The study was carried out on Norway rats selected through more than 60 generations for high and low fear-induced aggressiveness towards humans (Institute of Cytology and Genetics). The intensity of aggressive behavior towards man, reflex startle response, and expression of serotonin transporter (5-HTT) gene were studied. Selection for high aggression was associated with more intense startle response. The expression of 5-HTT gene in the frontal cortex was reduced significantly in rats selected for high aggression to humans in comparison with nonaggressive rats. The authors conclude that 5-HTT is involved in the regulation of genetically determined fear-induced aggression. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 147, No. 1, pp. 86-89, January, 2009