Radiographers and COVID-19 pneumonia: Diagnostic performance using CO-RADS.

INTRODUCTION: A more structured role of radiographers is advisable to speed up the management of patients with suspected COVID-19. The purpose of our study was to evaluate the diagnostic performance of radiographers in the detection of COVID-19 pneumonia on chest CT using CO-RADS descriptors. METHODS: CT images of patients who underwent RT-PCR and chest CT due to COVID-19 suspicion between March and July 2020 were analysed retrospectively. Six readers, including two radiologists, two highly experienced radiographers and two less experienced radiographers, independently scored each CT using the CO-RADS lexicon. ROC curves were used to investigate diagnostic accuracy, and Fleiss'κ statistics to evaluate inter-rater agreement. RESULTS: 714 patients (419 men; 295 women; mean age: 64 years ±19SD) were evaluated. CO-RADS> 3 was identified as optimal diagnostic threshold. Highly experienced radiographers achieved an average sensitivity of 58.7% (95%CI: 52.5-64.7), an average specificity of 81.8% (95%CI: 77.9-85.2), and a mean AUC of 0.72 (95%CI: 0.68-0.75). Among less experienced radiographers, an average sensitivity of 56.3% (95%CI: 50.1-62.2) and an average specificity of 81.5% (95%CI: 77.6-84.9) were observed, with a mean AUC of 0.71 (95%CI: 0.68-0.74). Consultant radiologists achieved an average sensitivity of 60.0% (95%CI: 53.7-65.8), an average specificity of 81.7% (95%CI: 77.8-85.1), and a mean AUC of 0.73 (95%CI: 0.70-0.77). CONCLUSION: Radiographers can adequately recognise the classic appearances of COVID-19 on CT, as described by the CO-RADS assessment scheme, in a way comparable to expert radiologists. IMPLICATIONS FOR PRACTICE: Radiographers, as the first healthcare professionals to evaluate CT images in patients with suspected SARS-CoV-2 infection, could diagnose COVID-19 pneumonia by means of a categorical reporting scheme at CT in a reliable way, hence playing a primary role in the early management of these patients.

Social Justice and the Promotion of the Common Good in Medical Missions to Low-Resourced Countries.

The article highlights the importance of critically examining medical missions to low-resourced countries in light of a bioethical focus on social justice and the promotion of the common good.

Mapping homeostatic synaptic plasticity using cable properties of dendrites.

When chronically silenced, cortical and hippocampal neurons homeostatically upregulate excitatory synaptic function. However, the subcellular position of such changes on the dendritic tree is not clear. We exploited the cable-filtering properties of dendrites to derive a parameter, the dendritic filtering index (DFI), to map the spatial distribution of synaptic currents. Our analysis indicates that young rat cortical neurons globally scale AMPA receptor-mediated currents, while mature hippocampal neurons do not, revealing distinct homeostatic strategies between brain regions and developmental stages. The DFI presents a useful tool for mapping the dendritic origin of synaptic currents and the location of synaptic plasticity changes.

[The reduction of the number of overweight students in a Rome school after two years]. / Riduzione del numero di ragazzi sovappeso: studio a distanza di due anni in una stessa scuola.

AIM: A study was conducted on children from a junior high school in Rome, Monteverde district, to observe data on hypertension and obesity. Data were compared with results from the study carried on two years ago in the same school by the same working group. METHODS: The study enrolled 336 students, 52% males and 48% females. Blood pressure was measured with Omron 2 automatic monitor, with child cuffs. Weight and height were measured with Seca scale with stadiometer. We assessed hypertension by means of recent Task Force Tables, overweight and obesity with the tables by Cole et al. RESULTS: A proportion of 5% of screened children presented hypertension, 13.9% overweight, 2.3% obesity. CONCLUSION: Prevalence of hypertension, overweight and obesity was lower than prevalence observed two years ago in the same school, thanks to a change in eating habits which included breakfast promotion, adoption of correct food choices for lunch and dinner, and most of all an increase in extracurricular sports activity, currently performed by 92% of students.

[Obesity and arterial hypertension in children: current calamity]. / Obesità ed ipertensione arteriosa in età pediatrica: flagello dei nostri giorni.

OBJECTIVES: A study was carried out on students of a middle school with a medium-high social level in a southern zone of Rome, to assess the current situation regarding obesity and arterial hypertension in subjects with a parental environment favouring correct eating habits. MATERIALS AND METHODS: We considered 693 students, mean age 11.2 + 0.6. Hypertension was defined according to blood pressure (BP) tables for children and adolescents of the NIH - Fourth Report (systolic and diastolic BP >95th percentile for age and sex). Overweight and obesity were determined according to the International Obesity Task Force. Dietary habits and life-style were investigated by specific questionnaires. RESULTS: The prevalence of overweight and obesity was respectively 23.1% and 3.3% of the subjects studied. Moreover, 5.2% of them showed BP values between 90th and 95th percentile and 7.8% was hypertensive. Food habits of the current students were fairly correct, favouring the Mediterranean diet and with the proper number of daily meals. DISCUSSION: A justification for the high number of hypertensive could be due to the elevated consumption of salt added to food (60% of young people), the elevated frequency of those who often eat fast food (43%) and a family history of hypertension in the parents (24%). Only 24.5% of males and 22.9% of females used to practice physical activity; whereas 40% of males and 41% of females used to spend more than 3 hours a day in front of the TV and/or computer.

The naturally occurring steroid solasodine induces neurogenesis in vitro and in vivo.

In this study, we explored the capacity of the naturally occurring compound solasodine to promote neurogenesis in vitro and in vivo. Mouse embryonic teratocarcinoma P19 cells exposed to solasodine for 2 days followed by a 5-day washout differentiated into cholinergic neurons that expressed specific neuronal markers and displayed important axonal formation that continued growing even 30 days after treatment. In vivo, a 2-week infusion of solasodine into the left ventricle of the rat brain followed by a 3-week washout resulted in a significant increase in bromodeoxyuridine uptake by cells of the ependymal layer, subventricular zone, and cortex that co-localized with doublecortin immunostaining, demonstrating the proliferative and differentiating properties of solasodine on neuronal progenitors. In addition, these data demonstrate that under our experimental conditions adult ependymal cells retrieved their proliferative and differentiating abilities. The GAP-43/HuD pathway was activated both in vitro and in vivo, suggesting a role in the differentiating process triggered by solasodine. Solasodine treatment in rats resulted in a dramatic increase in expression of the cholesterol- and drug-binding translocator protein in ependymal cells, suggesting a possible role played by neurosteroid production in solasodine-induced neurogenesis. In GAD65-GFP mice that express the green fluorescent protein under the control of the glutamic acid decarboxylase 65-kDa promoter, solasodine treatment increased the number of GABAergic progenitors and neuroblasts generated in the subventricular zone and present in the olfactory migratory tract. Taken together, these results suggest that solasodine offers an interesting approach to stimulate in situ neurogenesis from resident neuronal progenitors as part of neuron replacement therapy.

Analysis of a coloured Dutch map from the eighteenth century: the need for a multi-analytical spectroscopic approach using portable instrumentation.

A Dutch map from the eighteenth century was multi-analytically analysed making use of energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), Raman and scanning electron microscopy coupled to energy dispersive spectrometry (SEM-EDS). The cellulosic support was characterised and its state of conservation was evaluated. Besides, paramagnetic impurities were detected together with copper metallic chips. The colours present in some areas of the map were also analysed. Vermilion, carbon black and organic pigments were found. Surprisingly, in the green areas, the rare presence of the mineral moolooite (copper oxalate) was detected. A possible biological attack is discussed in order to explain the presence of such compound. Almost all of the techniques used in the analysis were portable, non-destructive and non-invasive, which is very desirable when analysing objects belonging to Cultural Heritage. The need for a multi-analytical approach using portable instrumentation is also discussed.

NAAG fails to antagonize synaptic and extrasynaptic NMDA receptors in cerebellar granule neurons.

The peptide transmitter N-acetylaspartylglutamate (NAAG) selectively activates the group II metabotropic glutamate receptors. Several reports also suggest that this peptide acts as a partial agonist at N-methyl-D-aspartate (NMDA) receptors but its putative antagonist effects have not been directly tested. To do this, we used whole cell recordings from cerebellar granule cells (CGC) in culture that allow the highest possible resolution of NMDA channel activation. When CGC were activated with equimolar concentrations of NMDA and NAAG, the peptide failed to alter the peak current elicited by NMDA. Very high concentrations of NAAG (100-200 microM) did not significantly reduce the current elicited by 10 microM NMDA or 0.1 microM glutamate, while 400 microM NAAG produced only a very small (less than 15%) reduction in these whole cell currents. Similarly, NAAG (400 microM) failed to significantly alter the average decay time constant or the peak amplitude of NMDA receptor-mediated miniature excitatory post-synaptic currents (mEPSCs). We conclude that high concentrations of the peptide do not exert physiologically relevant antagonist actions on synaptic NMDA receptor activation following vesicular release of glutamate. As an agonist, purified NAAG was found to be at least 10,000-fold less potent than glutamate in increasing "background" current via NMDA receptors on CGC. Inasmuch as it is difficult to confirm that NAAG preparations are completely free from contamination with glutamate at the 0.01% level, the peptide itself appears unlikely to have a direct agonist activity at the NMDA receptor subtypes found in CGC. Recent reports indicate that enhancing the activity of endogenous NAAG may be an important therapeutic approach to excitotoxicity and chronic pain perception. These effects are likely mediated by group II mGluRs, not NMDA receptors.

Functional expression of distinct NMDA channel subunits tagged with green fluorescent protein in hippocampal neurons in culture.

We generated expression vectors for N-terminally green fluorescent protein -tagged NR2A and NR2B subunits (GFP-NR2A and GFP-NR2B). Both constructs expressed GFP and formed functional NMDA channels with similar properties to untagged controls when co-transfected with NR1 subunit partner in HEK293 cells. Primary cultured hippocampal neurons were transfected at five days in vitro with these vectors. Fifteen days after transfection, well-defined GFP clusters were observed for both GFP-NR2A and GFP-NR2B subunits being co-localized with endogenous NR1 subunit. Whole-cell recordings showed that the GFP-NR2A subunit determined the decay of NMDA-mediated miniature spontaneous excitatory postsynaptic currents (NMDA-mEPSCs) in transfected neurons. Live staining with anti-GFP antibody demonstrated the surface expression of GFP-NR2A and GFP-NR2B subunits that was partly co-localized a presynaptic marker. Localization of NMDA receptor clusters in dendrites was studied by co-transfection of CFP-actin and GFP-NR2 subunits followed by anti-GFP surface staining. Within one week after plating most surface NMDAR clusters were distributed on dendritic shafts. Later in development, a large portion of surface clusters for both GFP-NR2A and GFP-NR2B subunits were clearly localized at dendritic spines. Our report provides the basis for studies of NMDA receptor location together with dendritic dynamics in living neurons during synaptogenesis in vitro.

Nitroxyl anion regulation of the NMDA receptor.

Nitric oxide (NO) is an important regulator of NMDA channel function in the CNS. Recent findings suggest that nitroxyl anion (NO(-)) may also be generated by nitric oxide synthase, which catalyzes production of NO. Using recombinant NMDA receptors (NMDA-r) transfected into human embryonic kidney cells, our data demonstrate that the nitroxyl anion donor, Angeli's salt (AS; Na(2)N(2)O(3)) dramatically blocked glycine-independent desensitization in NMDA-r containing NR1-NR2A subunits. AS did not affect glycine-dependent desensitization, calcium dependent inactivation or glutamate affinity for the NMDA-r. This effect could be mimicked by treatment with DPTA, a metal chelator and was not evident under hypoxic conditions. In contrast, receptors containing the NR1-NR2B subunits demonstrated an approximate 25% reduction in whole cell currents in the presence of AS with no apparent change in desensitization. Our data suggest that the regulation of NMDA-r function by nitroxyl anion is distinctly different from NO and may result in different cellular outcomes compared with NO.

Ribozyme-mediated reduction of the GABA(A) receptor alpha1 subunit.

As an approach to understanding the role of the alpha1 subunit of the GABA(A) receptor, ribozymes were designed to reduce expression of this subunit protein by hydrolysis of alpha1 subunit message and antisense inactivation. The ribozyme cleavage sites were selected through homology comparison of all known murine GABA(A) receptor subunits at the amino acid and nucleotide sequence level. Two ribozymes were designed and synthesized: one against the extracellular domain and the other against the cytoplasmic domain. These ribozymes were cloned in a mammalian expression plasmid, pZeoSV2 (+). Cleavage of both extracellular and cytoplasmic domain transcripts by the respective ribozymes was observed when each ribozyme was tested against in vitro transcribed mRNA. The stable cell line, 122, expressing recombinant human GABA(A) alpha1, beta2 and gamma2S subunits of receptor was stably transfected with the cytoplasmic domain ribozyme (cy) alone and with both the cytoplasmic (cy) and extracellular domain (ex) ribozyme expression plasmids. Northern analysis showed a 55-60% reduction of alpha1 mRNA in clones of cells transfected with either the single ribozyme (Cy) or with both ribozymes (EC). The alpha1 protein level was reduced 75% in a stable Cy clone and more than 90% in a stable EC clone when compared with alpha1 expression in 122 cells and the vector transfected (Zeo) cells. Electrophysiological analysis revealed that the GABA(A) receptor properties were very similar in 122 cells and in stable clones in which the subunit protein expression had been greatly reduced. No significant difference was detected in the potentiation of the receptor response by either bretazenil or zolpidem. These data demonstrate the efficacy of the ribozyme approach in dramatically reducing GABA(A) subunit protein levels in transfected cells and identify those elements that will be important to the application of similar ribozymes to knock-down transmitter receptor subunit proteins under inducible promoters in transgenic mice.

Exacerbation of neuronal cell death by activation of group I metabotropic glutamate receptors: role of NMDA receptors and arachidonic acid release.

Both ionotropic and metabotropic glutamate receptors have been implicated in the pathogenesis of neuronal injury. Activation of group I metabotropic glutamate receptors (mGluR) exacerbates neuronal cell death, whereas inhibition is neuroprotective. However, the mechanisms involved remain unknown. Activation of group I mGluR modulates multiple signal transduction pathways including stimulation of phosphoinositide hydrolysis, potentiation of NMDA receptor activity, and release of arachidonic acid. Here we demonstrate that whereas activation of group I mGluR by (S)-3,5-dihydroxyphenylglycine (DHPG) potentiates NMDA-induced currents and intracellular calcium increases in rat cortical neuronal cultures, partial effects of group I mGluR activation or inhibition on neuronal injury induced by oxygen-glucose deprivation remain despite NMDA receptor blockade. DHPG stimulation also increases basal arachidonic acid release from rat neuronal-glial cultures and potentiates injury-induced arachidonic acid release in these cultures. Thus, activation of group I mGluR may exacerbate neuronal injury through multiple mechanisms, which include positive modulation of NMDA receptors and enhanced release of arachidonic acid.

GABA(A) receptor alpha1 subunit deletion prevents developmental changes of inhibitory synaptic currents in cerebellar neurons.

Developmental changes in miniature IPSC (mIPSC) kinetics have been demonstrated previously in cerebellar neurons in rodents. We report that these kinetic changes in mice are determined primarily by developmental changes in GABA(A) receptor subunit expression. mIPSCs were studied by whole-cell recordings in cerebellar slices, prepared from postnatal day 11 (P11) and P35 mice. Similar to reports in granule neurons, wild-type cerebellar stellate neuron mIPSCs at P11 had slow decay kinetics, whereas P35 mIPSCs decayed five times faster. When mIPSCs in cerebellar stellate neurons were compared between wild-type (+/+) and GABA(A) receptor alpha1 subunit-deficient (-/-) littermates at P35, we observed dramatically slower mIPSC decay rates in -/- animals. We took advantage of the greater potency of imidazopyridines for GABA current potentiation with alpha1 subunit-containing receptors to characterize the relative contribution of alpha1 subunits in native receptors on inhibitory synapses of cerebellar granule neurons. Zolpidem-induced prolongation of mIPSC decay was variable among distinct cells, but it increased during development in wild-type mice. Similarly, Zolpidem prolongation of mIPSC decay rate was significantly greater in adult +/+ mice than in knock-outs. We propose that an increased alpha1 subunit assembly in postsynaptic receptors of cerebellar inhibitory synapses is responsible for the fast inhibitory synaptic currents that are normally observed during postnatal development.

Interleukin-10 prevents glutamate-mediated cerebellar granule cell death by blocking caspase-3-like activity.

Interleukin-10 (IL-10) has been shown to reduce neuronal degeneration after CNS injury. However, the molecular mechanisms underlying the neuroprotective properties of this cytokine are still under investigation. Glutamate exacerbates secondary injury caused by trauma. Thus, we examined whether IL-10 prevents glutamate-mediated cell death. We used rat cerebellar granule cells in culture because these neurons undergo apoptosis upon exposure to toxic concentrations of glutamate (100-500 microm) or NMDA (300 microm). Pretreatment of cerebellar granule cells with IL-10 (1-50 ng/ml) elicited a dose- and time-dependent reduction of glutamate-induced excitotoxicity. Most importantly, IL-10 reduced the number of apoptotic cells when added to the cultures together or 1 hr after glutamate. Using patch-clamping and fluorescence Ca(2+) imaging techniques, we examined whether IL-10 prevents glutamate toxicity by blocking the function of NMDA channel. IL-10 failed to affect NMDA channel properties and to reduce NMDA-mediated rise in intracellular Ca(2+). Thus, this cytokine appears to prevent glutamate toxicity by a mechanism unrelated to a blockade of NMDA receptor function. Various proteases, such as caspase-3, and transcription factors, such as nuclear factor kappaB (NF-kappaB), have been proposed to participate in glutamate-mediated apoptosis. Thus, we examined whether IL-10 modulates the activity of these apoptotic markers. IL-10 blocked both the glutamate-mediated induction of caspase-3 as well as NF-kappaB DNA binding activity, suggesting that the neuroprotective properties of IL-10 may rely on its ability to block the activity of proapoptotic proteins.

Distinct effect of pregnenolone sulfate on NMDA receptor subtypes.

Using rapid agonist applications to transfected HEK-293 cells, we investigated pregnenolone sulfate (PS) effects on deactivation and desensitization of recombinant NMDA receptors subtypes. PS prolonged the deactivation of responses produced by brief applications of L-glutamate with all subunit combinations tested. The action of PS was larger on NR1a/NR2A than on NR1a/NR2B channels. PS slowed the rate of macroscopic desensitization of the responses with all subunit combinations tested. In contrast, PS had little effect on current rise time and had much reduced action on responses with L-cysteate, a low affinity agonist. Our results suggest that PS decreases agonist unbinding. However, this action is counteracted by decreased desensitization. Since desensitization produces slow deactivating components, particularly with NR1a/NR2B receptors, this underlies the decreased PS effect with these subtypes. Indeed PS action was mainly observed on the fast component of deactivation. Furthermore, prolongation of NR1a/NR2A responses was similar to that of responses from NR1b/NR2B receptor, a subtype characterized by reduced desensitization. PS prolongation of evoked NMDA receptor mediated synaptic currents from cortical neuronal primary culture(s) was not significantly different from that of responses with NR1a/NR2B receptors indicating that native receptors in these neurons comprised at least some heteromeric combinations of these two subunits.

Cytosolic calcium oscillations in astrocytes may regulate exocytotic release of glutamate.

To obtain insights into the spatiotemporal characteristics and mechanism of Ca(2+)-dependent glutamate release from astrocytes, we developed a new experimental approach using human embryonic kidney (HEK) 293 cells transfected with the NMDA receptor (NMDAR), which act as glutamate biosensors, plated on cultured astrocytes. We here show that oscillations of intracellular Ca(2+) concentration ([Ca(2+)](i)) in astrocytes trigger synchronous and repetitive [Ca(2+)](i) elevations in sensor HEK cells, and that these elevations are sensitive to NMDAR inhibition. By whole-cell patch-clamp recordings, we demonstrate that the activation of NMDARs in HEK cells results in inward currents that often have extremely fast kinetics, comparable with those of glutamate-mediated NMDAR currents in postsynaptic neurons. We also show that the release of glutamate from stimulated astrocytes is drastically reduced by agents that are known to reduce neuronal exocytosis, i.e., tetanus toxin and bafilomycin A(1). We conclude that [Ca(2+)](i) oscillations represent a frequency-encoded signaling system that controls a pulsatile release of glutamate from astrocytes. The fast activation of NMDARs in the sensor cells and the dependence of glutamate release on the functional integrity of both synaptobrevin and vacuolar H(+) ATPase suggest that astrocytes are endowed with an exocytotic mechanism of glutamate release that resembles that of neurons.

Selective mGluR5 antagonists MPEP and SIB-1893 decrease NMDA or glutamate-mediated neuronal toxicity through actions that reflect NMDA receptor antagonism.

1. The metabotropic glutamate receptors (mGluRs) are a family of G-protein linked receptors that can be divided into three groups (group I, II and III). A number of studies have implicated group I mGluR activation in acute neuronal injury, but until recently it was not possible to pharmacologically differentiate the roles of the two individual subunits (mGluR1 and mGluR5) in this group. 2. We investigated the role of mGluR5 in acute NMDA and glutamate mediated neurodegeneration in cultured rat cortical cells using the mGluR5 antagonists MPEP and SIB-1893, and found that they provide significant protection at concentrations of 20 or 200 microM. 3. These compounds act as effective mGluR5 antagonists in our cell culture system, as indicated by the ability of SIB-1893 to prevent phosphoinositol hydrolysis induced by the specific mGluR5 agonist, (RS)-2-chloro-5-hydroxyphenylglycine (CHPG). 4. However, they also significantly reduce NMDA evoked current recorded from whole cells voltage clamped at -60 mV, and significantly decrease the duration of opening of NMDA channels recorded in the outside out patch configuration. 5. This suggests that although MPEP and SIB-1893 are effective mGluR5 antagonists, they also act as noncompetitive NMDA receptor antagonists. Therefore, the neuroprotective effects of these compounds are most likely mediated through their NMDA receptor antagonist action, and caution should be exercised when drawing conclusions about the roles of mGluR5 based on their use.

Analysis of GABAA receptor assembly in mammalian cell lines and hippocampal neurons using gamma 2 subunit green fluorescent protein chimeras.

Type A gamma-aminobutyric acid receptors (GABAA), the major sites of fast synaptic inhibition in the brain, are believed to be predominantly composed of alpha, beta, and gamma subunits. To examine the membrane trafficking of GABAA receptors we have produced gamma 2L subunit chimeras with green fluorescent protein (GFP). Addition of GFP to the N-terminus of the gamma 2 subunit (gamma 2L-GFPN) was functionally silent for alpha 1 beta 2 gamma 2L-GFPN receptors expressed in A293 cells. Furthermore, this chimera allowed the visualization of receptor membrane targeting and endocytosis in live cells. In contrast, incorporation of GFP at the C-terminus reduced subunit stability, impairing assembly with receptor alpha and beta subunits. Using gamma 2L-GFPN we were able to demonstrate that targeting of the gamma 2 subunit to GABAergic synapses in hippocampal neurons was dependent upon coassembly with receptor alpha and beta subunits. Together our results demonstrate that the assembly and membrane targeting of GABAA receptors composed of alpha 1 beta 2 gamma 2L-GFPN subunits follow similar itineraries in heterologous systems and neurons.

The gamma-aminobutyric acid type A (GABAA) receptor-associated protein (GABARAP) promotes GABAA receptor clustering and modulates the channel kinetics.

A microtubule-associated protein, gamma-aminobutyric acid type A (GABA(A)) receptor-associated protein (GABARAP), was previously identified as binding to the intracellular domain of GABA(A) receptors by using the yeast two-hybrid screen. In the present work, immunofluorescent staining and green fluorescent protein-tagged receptor subunits showed that GABARAP is associated with and promotes the clustering of GABA(A) receptors in QT-6 quail fibroblasts. The tubulin-binding motif of GABARAP and the gamma2 subunit of the receptor are required. Disruption of microtubules prevents the clustering in a time-dependent manner. When green fluorescent protein-tagged alpha1 or gamma2 subunit coexpressed with beta2, gamma2L, and GABARAP was used, recordings from visually identified cells revealed that clustered GABA(A) receptor had an EC(50) of about 20 microM, vs. 5.7 microM for the diffuse receptor. Clustered receptors deactivated faster and desensitized slower than the diffuse receptors, because of decrease in the apparent affinity of GABA binding. Different properties for clustered receptors relative to unclustered receptors in heterologous cells suggest that homologous differences between extrasynaptic and synaptic clustered receptors in neurons may be due to the organization of the postsynaptic machinery.

Increased exon 5 expression alters extrasynaptic NMDA receptors in cerebellar neurons.

We investigated the ontogenic changes in expression of alternatively spliced forms of NR1 protein that contain the N1 cassette (exon 5) in comparison with the total population of NR1 within the rat cerebellum. The N1 cassette is strongly developmentally regulated in the cerebellum, with >80% of total NR1 protein in the adult rat containing the N1 cassette. In contrast, early in development, <20% of NR1 protein contained this cassette. Rat cortices from the same ages did not show an increase in the percent of NR1 protein expressing the N1 cassette, indicating that the developmental changes in the cerebellum are tissue-specific. As the N1 cassette is known to determine NMDA receptor properties, including spermine sensitivity and decay kinetics of glutamate-induced currents, changes in the characteristics of glutamate-activated currents in granule cells from cerebellar slices were compared at postnatal day 7 versus 14. Glutamate responses exhibited fast deactivation kinetics and reduced potentiation by spermine at day 14 while maintaining sensitivity to an NR2B-selective antagonist. These data are consistent with the possibility that N1 cassette expression may be a factor in the developmental changes in properties of extrasynaptic NMDA receptors in the cerebellum.