Immunohistochemical comparison of T-cell and macrophage populations in mammary tissue of control and Trichinella spiralis-infected rats

We have shown that antigen-specific T lymphocytes can mediate maternal-to-neonatal immunity during lactation. Present studies address the dynamics of lymphocyte accumulation in the mammary gland during normal and disease stimulated conditions. Monoclonal antibodies specific for total T cells, suppressor/cytotoxic and helper subsets, and macrophages were used in conjunction with immunohistochemistry to identify and count the individual cell types. In unstimulated mammary tissue, following a rise in T cells to maximal numbers in late pregnancy, the total number of T cells/high power field (HPF) was significantly diminished in early lactation and continued to decline to the late lactation period. Both the numbers of T cells/HPF located in the mammary alveolar epithelium and surrounding connective tissue were significantly reduced in early lactation as compared to late pregnancy. This indicates the possible passage of cells into the milk during lactation. Prior infection of the mother with Trichinella spiralis and a secondary challenge 48 h. before sacrifice caused a significant reduction in the number of T cells in the mammary tissue in early lactation as compared with unstimulated controls, indicating the possibility of an even greater outflow of T cells into milk. In controls, the T-suppressor/cytotoxic subtype showed a reduction in early lactation versus late pregnancy but showed no shifts in total cells/HPF during infection. The T-helper subtype in controls remained unchanged from late pregnancy to early lactation with a considerable decline in late lactation. However, the T-helper cells were significantly decreased in T. spiralis-treated animals as compared with noninfected controls in early lactation.(ABSTRACT TRUNCATED AT 250 WORDS)     

B cell precursors are decreased in senescent BALB/c mice, but retain normal mitotic activity in vivo and in vitro

The numbers of phenotypic (sIg- Ly5[220]+) and functional B cell precursors were significantly reduced in the bone marrow of senescent (22-24 months old) BALB/c mice when compared to their young (2-4 months old) cohorts. Little alteration in the numbers of B cell precursors occurred during the first 12 months of life in this strain. In contrast, an accelerated loss of B cell precursors between 15 and 18 months of age was observed. In particular, the levels of small Ly5(220)+ B cell precursors were decreased with advanced age, although a decline in numbers of large sIg- Ly5(220)+ B cell precursors was also evident. The percentages of large sIg- Ly5(220)+ B cell precursors in (S + G2/M) stages of cell cycle were similar (e.g., 60-80%) in aged and young BALB/c mice. Importantly, Ly5(220)+ pre-B cells from both young and aged BALB/c mice, either present in vivo or derived from Ly5(220)- cells in vitro, were capable of proliferation in response to rIL-7. These observations suggest that the aging process results in a progressive decline in the numbers of pre-B cells; however, this apparently is not due to failure of B lineage precursor cells to respond to growth mediators either in vivo or in vitro.     

Excitatory and inhibitory postsynaptic currents in a rat model of epileptogenic microgyria

Developmental cortical malformations are common in patients with intractable epilepsy; however, mechanisms contributing to this epileptogenesis are currently poorly understood. We previously characterized hyperexcitability in a rat model that mimics the histopathology of human 4-layered microgyria. Here we examined inhibitory and excitatory postsynaptic currents in this model to identify functional alterations that might contribute to epileptogenesis associated with microgyria. We recorded isolated whole cell excitatory postsynaptic currents and GABA(A) receptor-mediated inhibitory currents (EPSCs and IPSCs) from layer V pyramidal neurons in the region previously shown to be epileptogenic (paramicrogyral area) and in homotopic control cortex. Epileptiform-like activity could be evoked in 60% of paramicrogyral (PMG) cells by local stimulation. The peak conductance of both spontaneous and evoked IPSCs was significantly larger in all PMG cells compared with controls. This difference in amplitude was not present after blockade of ionotropic glutamatergic currents or for miniature (m)IPSCs, suggesting that it was due to the excitatory afferent activity driving inhibitory neurons. This conclusion was supported by the finding that glutamate receptor antagonist application resulted in a significantly greater reduction in spontaneous IPSC frequency in one PMG cell group (PMG(E)) compared with control cells. The frequency of both spontaneous and miniature EPSCs was significantly greater in all PMG cells, suggesting that pyramidal neurons adjacent to a microgyrus receive more excitatory input than do those in control cortex. These findings suggest that there is an increase in numbers of functional excitatory synapses on both interneurons and pyramidal cells in the PMG cortex perhaps due to hyperinnervation by cortical afferents originally destined for the microgyrus proper.     

Immunohistochemical comparison of T-cell and macrophage populations in mammary tissue of control and Trichinella spirails-infected rats

We have shown that antigen-specific T lymphocytes can mediate maternal-to-neonatal immunity during lactation. Present studies address the dynamics of lymphocyte accumulation in the mammary gland during normal and disease stimulated conditions. Monoclonal antibodies specific for total T cells, suppressor/cytotoxic and helper subsets, and macrophages were used in conjunction with immunohistochemistry to identify and count the individual cell types. In unstimulated mammary tissue, following a rise in T cells to maximal numbers in late pregnancy, the total number of T cells/high power field (HPF) was significantly diminished in early lactation and continued to decline to the late lactation period. Both the numbers of T cells/HPF located in the mammary alveolar epithelium and surrounding connective tissue were significantly reduced in early lactation as compared to late pregnancy. This indicates the possible passage of cells into the milk during lactation. Prior infection of the mother with Trichinella spiralis and a secondary challenge 48 h. before sacrifice caused a significant reduction in the number of T cells in the mammary tissue in early lactation as compared with unstimulated controls, indicating the possibility of an even greater outflow of T cells into milk. In controls, the T-suppressor/cytotoxic subtype showed a reduction in early lactation versus late pregnancy but showed no shifts in total cells/HPF during infection. The T-helper subtype in controls remained unchanged from late pregnancy to early lactation with a considerable decline in late lactation. However, the T-helper cells were significantly decreased in T. spiralis-treated animals as compared with noninfected controls in early lactation. The population of macrophages declined from late pregnancy to early lactation but remained unchanged between normal and T. spiralis-infected animals.     

大鼠脊髓半横断损伤后大脑皮质初级运动区caspase-3的表达

目的探讨大鼠脊髓半横断损伤（hSCI）后大脑皮质初级运动区（M1）神经细胞的凋亡情况。方法成年健康Wistar大鼠T8-9脊髓左侧半横断术后，用RT-PCR和免疫组织化学法检测各个时间点caspase-3mRNA的表达量以及阳性细胞的分布。结果手术组中左、右两侧M1区的caspase-3mRNA表达量与假手术组比较，在6h即显著上升，1d达到高峰，3d、7d、14d组下降，而在21d又略有上升；6h组M1区表达量右侧明显高于左侧。免疫组织化学显示阳性细胞主要集中在M1的多形细胞层、锥体层。结论大鼠脊髓半横断损伤后M1细胞凋亡在早期最为剧烈，不仅导致支配损伤侧的M1区细胞凋亡，同样也导致支配未损伤侧脊髓的M1区神经细胞凋亡。     

Alterations in peripheral B cells and B cell progenitors following androgen ablation in mice

The production of B lymphocytes is regulated in part by physiologic levels of androgens and estrogens. While these sex hormones down-regulate B lymphopoiesis, augmentation of B lymphopoiesis occurs under conditions where androgen or estrogen levels are decreased. In this study we examine the effect of androgen ablation of male mice on B lymphopoiesis and on the phenotypic composition of peripheral B lymphocyte populations. Spleen and thymic weights are significantly increased following castration, as is the total number of peripheral blood lymphocytes. However, the absolute numbers of B cells in the periphery are selectively increased following castration; the numbers of T cells, NK cells and granulocytes remain unchanged. The increase in circulating B cells is due largely to increases in the numbers of recent bone marrow emigrants expressing a B220(lo+)CD24(hi+) phenotype and these cells remain significantly elevated in castrated mice for up to 54 days post-castration. Similar increases in the percentages of newly emigrated B cells are observed in mice that lack a functional androgen receptor (TFM:). Finally, assessments of B cell progenitors in the bone marrow revealed significant increases in the relative numbers of IL-7-responsive B cell progenitors, including cells in Hardy fractions B (early pro-B cells), C (late pro-B cells), D (pre-B cells) and E (immature B cells). These findings demonstrate that androgen ablation following castration significantly and selectively alters the composition of peripheral B cells in mice. Further, these alterations result from the potentiating effects of androgen ablation on IL-7-responsive pro-B cell progenitors.     

Changes in numbers of acidophilic and basophilic connective tissue granulated cells in the intestine of the rat during the estrous cycle

Changes in physiological reproductive states of female Long-Evans hooded rats were directly correlated with changes in the concentration of acidophilic and basophilic connective tissue granulated cells in the lamina propria of the duodenum. Acidophilic granulated cell numbers were significantly higher at estrus and metestrus than at other stages of the estrous cycle or in the immature state. Acidophilic granulated cell numbers during pregnancy were not significantly different from cell numbers quantified during metestrus, diestrus, or proestrus, but were significantly lower than cell numbers during estrus. Late lactation (21-25 days) was associated with significant decreases in the numbers of acidophilic granulated cells from numbers observed during the estrous cycle and during pregnancy. Basophilic granulated cell numbers did not differ significantly during the estrous cycle, although the highest numbers were observed during proestrus. Basophilic granulated cell numbers were significantly higher during pregnancy than during the estrous cycle. Basophilic granulated cell counts in late lactation were comparable to numbers quantified in estrus, metestrus, and diestrus, but were significantly lower than during proestrus and pregnancy.     

Age-associated decline in natural killer (NK) activity reflects primarily a defect in function of NK cells

The possible role that natural killer (NK) cells might play in the control of tumors and certain infections prompted an investigation of the status of NK cells in aged mice of two inbred strains (C3H and C57BL/6). The frequency of NK cells in young-adult and aged mice was assessed by two methods that provided accurate estimates of the relative numbers of NK cells: (a) a functional assay procedure from which the number of lytic units could be estimated, and (b) a target-cell (YAC-1 tumor cells) binding procedure. The frequency of NK cells in the spleens of untreated mice as well as in mice infected with Trypanosoma musculi, the latter a powerful NK cell activating agent, was determined. In both strains of mice the frequency of functionally-competent NK cells declined significantly with age, to a greater extent in C3H than in C57BL/6 mice. Similarly, the potential to generate NK cells upon parasite activation was significantly less in aged than in young mice and the reduced potential was more apparent in C3H than in C57BL/6 mice. In contrast, the target cell-binding procedure showed only a modest decline in the frequency of NK cells in the spleens of aged mice of either strain. It appears, therefore, that the decline in NK activity during aging is a reflection of loss of competence to lyse targets rather than a major decline in the actual numbers of NK cells.     

Changes in numbers of acidophilic and basophilic connective tissue granulated cells in the intestine of the rat during the estrous cycle.

Changes in physiological reproductive states of female Long-Evans hooded rats were directly correlated with changes in the concentration of acidophilic and basophilic connective tissue granulated cells in the lamina propria of the duodenum. Acidophilic granulated cell numbers were significantly higher at estrus and metestrus than at other stages of the estrous cycle or in the immature state. apcidophilic granulated cell numbers during pregnancy were not significantly different from cell numbers quantified during metestrus, diestrus, or proestrus, but were significantly lower than cell numbers during estrus. Late lactation (21-25 days) was associated with significant decreases in the numbers of acidophilic granulated cells from numbers observed during the estrous cycle and during pregnancy. Basophilic granulated cell numbers did not differ significantly during the estrous cycle, although the highest numbers were observed during proestrus. Basophilic granulated cell numbers were significantly higher during pregnancy than during the estrous cycle. Basophilic granulated cell counts in late lactation were comparable to numbers quantified in estrus, metestrus, and diestrus, but were significantly lower than during proestrus and pregnancy.     

Suppression of Target Cell Proliferation by Natural Killer Cells

The cytolytic effects of natural killer (NK) cells have been extensively studied in recent years. In the present study we have investigated the cytostatic effects of NK cells. Human peripheral blood lymphocytes from healthy volunteers were used as a source of effector cells, and the cell lines K562, U937, U1285, and Molt-4 were used as target cells. Effector cells were enriched for NK cells using Percoll gradients and depleted of NK cells on Percoll gradients or by using Leu-19 antibodies and magnetic beads. By monitoring cell numbers during co-culture of effector cells and K562, it was found that after an initial phase of cell killing for 3 h target cell numbers remained stable during the following 24-48 h. In a microcytotoxicity assay measuring inhibition of uptake of [3H]thymidine, the four target cell types were shown to have different NK sensitivity; inhibition of greater than or equal to 80% was obtained for K562 and U937 at an effector to target cell (E/T) ratio of 30:1, 50% for U1285, and 30% for Molt-4. This inhibition was shown to be partly a direct effect on DNA synthesis for all cell lines, as incorporation of [3H]thymidine was decreased in cocultured target cells compared with an equal number of target cells alone. Inhibition of DNA synthesis was thus not directly related to cell death and was also observed for the Molt-4 cell line that was not killed. A cell division assay, with target cells in agarose and effector cells in a liquid upper layer, showed a decline in the rate of target cell divisions. Effects on the cell cycle were studied on latent-phase cells. It was shown that effector cells delayed the onset of DNA synthesis. This anti-proliferative effect was observed for several days, but cell growth then gradually resumed. The effector cells were identified as CD56-positive large granular lymphocytes (LGL). Double-layer cultures and experiments using effector cell supernatants demonstrated that the growth-inhibitory effect could be mediated by soluble factors, and the production of such factors was stimulated by exposure to a small proportion of target cells (50:1). Studies with specific antibodies indicated that growth inhibition was not mediated by alpha interferon (IFN-alpha) but it was partly mediated by tumour necrosis factor alpha (TNF-alpha). It is concluded that NK cells have a growth-inhibitory effect that is distinct from the cytolytic effect and this activity is probably mediated by several soluble factors including TNF-alpha.     

Histometric changes and cell death in the thalamus after neonatal neocortical injury in the rat

Freezing injury to the developing cortical plate results in a neocortical malformation resembling four-layered microgyria. Previous work has demonstrated that following freezing injury to the somatosensory cortex, males (but not females) have more small and fewer large cells in the medial geniculate nucleus. In the first experiment, we examined the effects of induced microgyria to the somatosensory cortex on neuronal numbers, neuronal size, and nuclear volume of three sensory nuclei: ventrobasal complex, dorsal lateral geniculate nucleus, and medial geniculate nucleus. We found that there was a decrease in neuronal number and nuclear volume in ventrobasal complex of microgyric rats when compared with shams, whereas there were no differences in these variables in the dorsal lateral geniculate nucleus or medial geniculate nucleus. We also found that there were more small and fewer large neurons in both ventrobasal complex and medial geniculate nucleus. In experiment 2, we attempted to determine the role of cell death in the thalamus on these histometric measures. We found that cell death peaked within 24 h of the freezing injury and was concentrated mostly in ventrobasal complex. In addition, there was evidence of greater cell death in males at this age. Taken together, these results support the notion that males are more severely affected by early injury to the cerebral cortex than females.     

Mild traumatic brain injury induces apoptotic cell death in the cortex that is preceded by decreases in cellular Bcl-2 immunoreactivity

Although mild traumatic brain injury is associated with behavioral dysfunction and histopathological alterations, few studies have assessed the temporal pattern of regional apoptosis following mild brain injury. Anesthetized rats were subjected to mild lateral fluid-percussion brain injury (1.1–1.3 atm), and brains were evaluated for the presence of in situ DNA fragmentation (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling, TUNEL) and morphologic characteristics of apoptotic cell death (nuclear and cytoplasmic condensation, presence of apoptotic bodies). Significant numbers of apoptotic TUNEL(+) cells were observed in the injured parietal cortex and underlying white matter up to 72 h post-injury (P<0.05 compared to sham-injured-injured), with maximal numbers present at 24 h. Apoptosis was confirmed by the presence of 180–200 bp nuclear DNA fragments in tissue homogenates. The appearance of apoptotic TUNEL(+) cells in the injured cortex was preceded by a marked decrease in immunoreactivity for the anti-cell death protein, Bcl-2, as early as 2 h post-injury. This decrease in cellular Bcl-2 staining was not accompanied by a concomitant loss of staining for the pro-cell death Bax protein, suggesting that post-traumatic neuronal death in the cortex may be dependent on altered cellular ratios of Bcl-2:Bax. In the hippocampus, no significant increase in apoptotic TUNEL(+) cells was observed compared to sham-injured-injured animals. However, selective neuronal loss was evident in the CA3 region at 24 h post-injury, that was preceded by an overt loss of neuronal Bcl-2 immunoreactivity at 6 h. No changes in either cellular Bcl-2 or Bax expression were observed in the thalamus or white matter at any time post-injury.

Taken together from these data, we suggest that apoptosis contributes to cell death in both gray and white matter, and that decreases in cellular Bcl-2 may, in part, be associated with both apoptotic and non-apoptotic cell death following mild brain trauma.     

Increased caspase activity primes human Lyme arthritis synovial γδ T cells for proliferation and death

γδ T cells function between the innate and adaptive immune responses, promoting antigen-presenting cell function and manifesting cytolytic activity. Their numbers often increase during infections, such as human immunodeficiency virus, and at sites of chronic inflammation. However, the turnover dynamics of human γδ T cells are poorly understood. Here we observed that despite more rapid proliferation in vitro by human Lyme arthritis synovial γδ T cells of the Vδ1 subset, they have reduced surviving cell numbers compared with αβ T cells because of increased cell death by the γδ T cells. Because caspases are involved in cell proliferation and death, and because signaling is more efficient through T cell receptor (TCR)-γδ than through TCR-αβ, we examined the levels of active caspases during cell cycling and following TCR restimulation. We observed higher overall caspase activity in Borrelia-reactive γδ T cells than in comparable αβ T cells. This was paralleled by greater spontaneous cell death and TCR restimulation-induced cell death of the γδ T cells, which was caspase dependent. Our current findings thus are consistent with a model in which human γδ T cells evolved to function quickly and transiently in an innate fashion.     

Perineuronal germinal cells in the rat cerebral cortex

The generation and renewal of cells in the adult mammalian central nervous system maintains brain functions, including plasticity. Even in the cerebral cortex of adult mammals, glial cells are thought to be replaced with newly generated cells every 100 days. Recently, we demonstrated that this proliferation is stimulated by neural activity. However, whether any germinal areas exist in the cortical parenchyma is unknown. Here, we examined the proliferating cell dynamics in the cerebral cortex of adult rats using BrdU labeling and immunohistochemistry for NeuN and lamin B1. At 2 h after a single injection of BrdU, more than 80% of BrdU-labeled cells were observed in the perineuronal territory in which the BrdU-labeled nuclei were located within 5 μm from neuronal nuclei. The ratio of perineuronal cells to nonperineuronal cells in BrdU-labeled cells gradually decreased over the 2 weeks following BrdU injection. These observations indicate that numerous cortical cells proliferate in the perineuronal territory, the germinal soil, and that part of these newly generated cells migrate from the perineuronal territory into the surrounding areas during the 2 weeks following mitosis.     

纯视细胞移植术后RCS鼠视皮质内γ—氨基丁酸的分布

目的：通过成功地纯视细胞移植,观察RCS鼠视皮质内抑制性神经递质γ-氨基丁酸（GABA）的分布和变化。方法：取同龄Wistar/皇家外科学院（Royal College of Surgeon,RCS)鼠为供／受体,准分子激光切削法制备视细胞层,外路途径移入RCS鼠的视网膜下腔,术后2周取RCS鼠手术组眼、手术对照组眼、RCS对照组眼及其视皮质分别做冰冻切片、免疫组织化学染色染法色、普通光学显微镜下观察。结果：视细胞细胞术后2周,移植视细胞存活,外丛状层重建,与手术对照眼,RCS对照相相比,重视高膜受体RCS鼠对侧视皮质内GABA免疫反应神经元数量较多,而同侧视皮质内无GABA免疫反应神经元。结论：成功纯视网细胞移植可以重建RCS鼠的视传导通路,移植的纯视细胞使RCS鼠视皮质内GABA免疫反应的分布发生变化。     

Age-Related Changes in Human Blood Lymphocyte Subpopulations: II. Varying Kinetics of Percentage and Absolute Count Measurements

A reference range for lymphocyte populations, with particular emphasis on T lymphocyte subsets, was obtained for normal individuals covering age cohorts from birth through adulthood. This report confirms and extends findings from a developmental reference range published earlier (1). Absolute numbers of WBC, lymphocytes, and T, B, and NK subsets decline significantly during childhood. However, differences in the rate of decline of certain lymphocyte subsets leads to discordance between absolute numbers and percentages. Those lymphocyte subsets which decline less rapidly with age than the total lymphocyte count will show an increase in percentage, whereas those which decline more rapidly will show further declines in percentage values. T cell percentages were seen to increase over time whereas B cell percentages decline. Markers of immaturity such as CD45RA on CD4 cells and CD38 on CD8 cells declined in both percentages and absolute numbers. Activation markers, such as HLA-DR on CD8 cells and IL2-R on CD3 cells, increased in percentages with time but changed inconsistently in cell number from infancy to adulthood. These findings extend the lymphocyte reference range to markers thought to be informative in various disease states, including HIV infection.     

Zinc histochemistry reveals circuit refinement and distinguishes visual areas in the developing ferret cerebral cortex

A critical question in brain development is whether different brain circuits mature concurrently or with different timescales. To characterize the anatomical and functional development of different visual cortical areas, one must be able to distinguish these areas. Here, we show that zinc histochemistry, which reveals a subset of glutamatergic processes, can be used to reliably distinguish visual areas in juvenile and adult ferret cerebral cortex, and that the postnatal decline in levels of synaptic zinc follows a broadly similar developmental trajectory in multiple areas of ferret visual cortex. Zinc staining in all areas examined (17, 18, 19, 21, and Suprasylvian) is greater in the 5-week-old than in the adult. Furthermore, there is less laminar variation in zinc staining in the 5-week-old visual cortex than in the adult. Despite differences in staining intensity, areal boundaries can be discerned in the juvenile as in the adult. By 6 weeks of age, we observe a significant decline in visual cortical synaptic zinc; this decline was most pronounced in layer IV of areas 17 and 18, with much less change in higher-order extrastriate areas during the important period in visual cortical development following eye opening. By 10 weeks of age, the laminar pattern of zinc staining in all visual areas is essentially adultlike. The decline in synaptic zinc in the supra- and infragranular layers in all areas proceeds at the same rate, though the decline in layer IV does not. These results suggest that the timecourse of synaptic zinc decline is lamina specific, and further confirm and extend the notion that at least some aspects of cortical maturation follow a similar developmental timecourse in multiple areas. The postnatal decline in synaptic zinc we observe during the second postnatal month begins after eye opening, consistent with evidence that synaptic zinc is regulated by sensory experience.     

Proliferation and differentiation of progenitor cells in the cortex and the subventricular zone in the adult rat after focal cerebral ischemia

Progenitor cells in the subventricular zone of the lateral ventricle and in the dentate gyrus of the hippocampus can proliferate throughout the life of the animal. To examine the proliferation and fate of progenitor cells in the subventricular zone and dentate gyrus after focal cerebral ischemia, we measured the temporal and spatial profiles of proliferation of cells and the phenotypic fate of proliferating cells in ischemic brain in a model of embolic middle cerebral artery occlusion in the adult rat. Proliferating cells were labeled by injection of bromodeoxyuridine (BrdU) in a pulse or a cumulative protocol. To determine the temporal profile of proliferating cells, ischemic rats were injected with BrdU every 4 h for 12 h on the day preceding death. Rats were killed 2-14 days after ischemia. We observed significant increases in numbers of proliferating cells in the ipsilateral cortex and subventricular zone 2-14 days with a peak at 7 days after ischemia compared with the control group. To maximize labeling of proliferating cells, a single daily injection of BrdU was administered over a 14-day period starting the day after ischemia. Rats were killed either 2 h or 28 days after the last injection of BrdU. A significant increase in numbers of BrdU immunoreactive cells in the subventricular zone was coincident with a significant increase in numbers of BrdU immunoreactive cells in the olfactory bulb 14 days after ischemia and numbers of BrdU immunoreactive cells did not significantly increase in the dentate gyrus. However, 28 days after the last labeling, the number of BrdU labeled cells decreased by 90% compared with number at 14 days. Clusters of BrdU labeled cells were present in the cortex distal to the infarction. Numerous cells immunostained for the polysialylated form of the neuronal cell adhesion molecule were detected in the ipsilateral subventricular zone. Only 6% of BrdU labeled cells exhibited glial fibrillary acidic protein immunoreactivity in the cortex and subcortex and no BrdU labeled cells expressed neuronal protein markers (neural nuclear protein and microtubule associated protein-2). From these data we suggest that focal cerebral ischemia induces transient and regional specific increases in cell proliferation in the ipsilateral hemisphere and that proliferating progenitor cells may exist in the adult cortex.     

Developmental aspects of the neocortex of the bat

Golgi studies on the cerebral cortex (central region) of newborn and adult bats (Myotis myotis) have shown that (a) extraverted cells in layer II-III are the source of a rich horizontal plexus originating from large numbers of long, proximal axonic collaterals, and (b) significantly greater numbers of basilar and apical dendrites (Student's t-test, P less than 0.001) of extraverted pyramidal cells are found in the newborn than in the adult bat, indicating an overproduction of dendrites during the early stages of development.     

Differential increase in the expression of heat shock protein family members during sleep deprivation and during sleep

Although sleep is thought to be restorative from prior wakeful activities, it is not clear what is being restored. To determine whether the synthesis of macromolecules is increased in the cerebral cortex during sleep, we subjected C57BL/6 mice to 6 hours of sleep deprivation and then screened the expression of 1176 genes of known function by using cDNA arrays. The expression of the heat shock proteins (HSP), endoplasmic reticulum protein (ERp72) and glucose-regulated protein (GRp78), was among the genes whose expression was significantly elevated in the cortex during sleep deprivation, whereas GRp78 and GRp94 mRNAs were elevated in the cortex during recovery sleep after sleep deprivation, as confirmed by conventional and quantitative real-time polymerase chain reaction and/or Northern analyses. A systematic evaluation of the expression of six heat shock protein family members (ERP72, GRp78, GRp94, HSP27, HSP70-1, and HSP84) in seven brain regions revealed increased mRNA levels in cortex, basal forebrain, hypothalamus, cerebellum and medulla during sleep deprivation, whereas increased mRNA levels during recovery sleep were limited to the cortex and medulla. Immunohistochemical studies identified increased numbers of GRp78-, GRp94-, and ERp72-immunoreactive cells in the dorsal and lateral cortex during sleep deprivation but, during recovery sleep, elevated numbers of these cells were found only in the lateral cortex. In the medulla, increased numbers of GRp94-immunoreactive cells were observed in nucleus tractus solitarius, dorsal motor nucleus of the vagus and the rostroventrolateral medulla during recovery sleep. The widespread increase of heat shock protein family mRNAs in brain during sleep deprivation may be a neuroprotective response to prolonged wakefulness. In contrast, the relatively limited heat shock protein family mRNA expression during recovery sleep may be related to the role of heat shock proteins in protein biogenesis and thus to the restorative function of sleep.