Filamin A mutations cause periventricular heterotopia with Ehlers-Danlos syndrome.

OBJECTIVE: To define the clinical, radiologic, and genetic features of periventricular heterotopia (PH) with Ehlers-Danlos syndrome (EDS). METHODS: Exonic sequencing and single stranded conformational polymorphism (SSCP) analysis was performed on affected individuals. Linkage analysis using microsatellite markers on the X-chromosome was performed on a single pedigree. Western blotting evaluated for loss of filamin A (FLNA) protein and Southern blotting assessed for any potential chromosome rearrangement in this region. RESULTS: The authors report two familial cases and nine additional sporadic cases of the EDS-variant form of PH, which is characterized by nodular brain heterotopia, joint hypermobility, and development of aortic dilatation in early adulthood. MRI typically demonstrated bilateral nodular PH, indistinguishable from PH due to FLNA mutations. Exonic sequencing or SSCP analyses of FLNA revealed a 2762 delG single base pair deletion in one affected female. Another affected female harbored a C116 single point mutation, resulting in an A39G change. A third affected female had a 4147 delG single base pair deletion. One pedigree with no detectable exonic mutation demonstrated positive linkage to the FLNA locus Xq28, an affected individual in this family also had no detectable FLNA protein, but no chromosomal rearrangement was detected. CONCLUSION: These results suggest that the Ehlers-Danlos variant of periventricular heterotopia (PH), in part, represents an overlapping syndrome with X-linked dominant PH due to filamin A mutations.

A comparison of the density of NADPH-diaphorase-reactive neurons in the fascia dentata and Ammon's horn between 6-month and 12-month old dark agouti rats.

The present study aimed to assess the developmental progress of the hippocampal nitric oxide (NO) system within adulthood by comparing the density of NO-producing neurons in the fascia dentata and Ammon's horn in two groups of adult male rats using NADPH-diaphorase (NADPH-d) histochemistry. One group comprised 6-month-old rats (early adulthood), and the other 12-month-old rats (middle-adulthood). Areal density (number of neurons per unit area) of NADPH-d positive neurons along the three hippocampal axes (septo-temporal, transverse and radial axes) were subjected to quantitative analyses. There were significant variations in the density of NADPH-d-reactive neurons along the transverse and radial axes of the hippocampus, similar to what have been described previously. Comparison between 6-month and 12-month-old rats indicated a substantial reduction in the density of NADPH-d-reactive neurons in the fascia dentata (69%) and Ammon's horn (54%) of the latter group. This reduction was relatively uniform along the septotemporal and radial axes, but appeared to be more pronounced in the fascia dentata and in the proximal region of Ammon's horn. Our finding showed that the hippocampal NO system can undergo significant changes within adulthood. It further highlighted the possibility that an age-related reduction in the capacity to produce NO may not be directly responsible for the cognitive decline associated with senescence, but rather predisposes neuronal degeneration in later life.

Neonatal nonhandling and in utero prenatal stress reduce the density of NADPH-diaphorase-reactive neurons in the fascia dentata and Ammon's horn of rats.

The density of nitric oxide (NO)-producing neurons in the fascia dentata and Ammon's horn was assessed in 6-month-old male rats using NADPH-diaphorase (NADPH-d) histochemistry. Two separate experiments investigated whether (1) the complete absence of neonatal handling or (2) the administration of periodic prenatal stress could affect the expression and distribution of NADPH-d reactivity in the hippocampus, when compared with rats raised in normal standard laboratory conditions. Experiment 1 demonstrated that adult rats that received no handling during neonatal development (from birth to postnatal day 22) showed a very substantial reduction in NADPH-d-positive neurons per unit area throughout the entire hippocampus when compared with rats that received regular daily handling in this period. Quantitative analysis further revealed that this effect was significantly more pronounced in Ammon's horn than in the fascia dentata, and within Ammon's horn the dorsal region was selectively more affected. Experiment 2 showed that prenatal stress, which involved the administration of daily restraint stress to pregnant dams throughout the gestation period, also led to a reduction in NADPH-d reactivity in the hippocampus of the offspring of these dam when they reached adulthood. The present results suggest that behavioral manipulations in the early neonatal or prenatal period can significantly alter the neurodevelopment of the hippocampal NO system and these changes might be related to some of the behavioral abnormalities that emerge later in adulthood.

Local-circuit neurones in the medial prefrontal cortex (areas 25, 32 and 24b) in the rat: morphology and quantitative distribution.

This paper is a light microscopical study describing the detailed morphology and quantitative distribution of local circuit neurones in areas 25, 32, and 24b of the medial prefrontal cortex (mPFC) in the rat. Cortical interneurones were identified immunocytochemically by their expression of calretinin (CR), parvalbumin (PV), and calbindin D-28k (CB) immunoreactivity. Neurones immunoreactive for gamma-aminobutyric acid (GABA) were also investigated, as were interneurones containing reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activity. Several distinct classes of CR+, PV+, and CB+ neurones were identified; the most frequent were: bipolar/bitufted CR+ cells in upper layer 3; multipolar PV+ neurones in layers 3 and 5; and bitufted/multipolar CB+ neurones in lower layer 3. CB+ neurones resembling Martinotti and neurogliaform cells were also present in layers 5/6. The morphologies and depth distributions of each cell type were consistent across the three areas of mPFC studied. Seven classes of diaphorase-reactive mPFC neurone are described; these cells were composed about 0.8% of the total neurone population and had a peak distribution located in mid- to lower layer 5 in each area. In areas 32 and 25, three defined bands of diffuse NADPH diaphorase staining were located in layer 2 and in upper and deep layer 5. Diaphorase reactivity was very infrequently colocalised with either CR, PV, or CB immunoreactivities. The numerical densities of neurones (N(V), number of cells per mm3) in each layer were calculated stereologically. The mean total neuronal N(V) estimate for areas 25, 32, and 24b was 51,603 +/- 3,324 (mean +/- S.D.; n = 8). Significant interareal differences were detected. From cortical thickness data and neuronal N(V) estimates, the absolute number of neurones under 1 mm2 of cortical surface (N(C)) have been derived. The mean N(C) value for areas 25, 32, and 24b was 57,328 +/- 7,505 neurones. In immunolabelled Nissl-stained sections, CR+ neurones constituted an overall 4.0%, PV+ cells 5.6%, and CB+ 3.4% of the total neurone populations in mPFC. GABA+ cells represented a mean of 16.2% (14.8-17.2%) of neurones in areas 25, 32 and 24b. The absolute numbers of CR+, PV+, CB+, and GABA+ neurones within individual layers in a column of cortex under 1 mm2 of cortical surface (N(L)) have also been derived, with significant interareal differences in N(L) values being detected. The data provide the structural basis for a qualitative and quantitative definition of local cortical circuits in the rat mPFC.

NADPH-diaphorase reactive pyramidal neurons in Ammon's horn and the subiculum of the rat hippocampal formation.

NADPH-diaphorase histochemistry has been shown to stain cells which contain nitric oxide synthase, an enzyme responsible for the biosynthesis of the freely diffusable gas nitric oxide. A number of studies have mapped the distribution of NADPH-diaphorase-reactive neurons in the hippocampal formation but they have failed to yield consistent data. The major point of controversy concerns the presence of NADPH-diaphorase-reactive pyramidal cells in the CA1 subfield of the rat hippocampal formation. The present results show that CA1 pyramidal neurons do contain nitric oxide synthase (NOS) which can be reliably demonstrated with the appropriate histochemical procedure. One of the critical determinants of CA1 pyramidal cell NADPH-diaphorase activity is shown to be incubation of brains in sucrose solution prior to histochemical processing. Subicular pyramidal cells were also found to contain NOS and to possess NADPH-diaphorase activity. These results explain a number of contradictory reports in the literature relating to the presence of NADPH-diaphorase activity in hippocampal principal cells. Additionally, densitometric analysis carried out on 20 microns thick sections, from brains incubated in sucrose solution, indicated that there were characteristic gradients. The intensity of NADPH-diaphorase activity in pyramidal cells located in the ventral subiculum was found to be greater than those in the dorsal subiculum. A similar, yet marginal, trend was apparent for pyramidal cells in CA1 and CA3, as well as nonpyramidal cells in CA1. At both dorsal and ventral levels, NADPH-diaphorase-positive subicular pyramidal cells and CA1 nonpyramidal cells also show a greater intensity than CA1 or CA3 reactive pyramidal neurons. This study also showed that tissue incubation in sucrose solution prior to immunocytochemistry, enhanced immunoreactivity of the endothelial isoform of NOS whilst having little effect on neuronal NOS reactivity.