Reference intervals and reliability of cavum septi pellucidi volume measurements by three-dimensional ultrasound between 19 and 24 weeks' gestation.

OBJECTIVES: A small or a large cavum septi pellucidi (CSP) during routine second trimester sonography may suggest abnormal cerebral development. Therefore, determination of CSP volume with three-dimensional (3D) ultrasound can be valuable. For this purpose, we sought to evaluate the reference ranges and measurement reliability of CSP volume by Virtual Organ Computer-aided AnaLysis (VOCAL). METHODS: VOCAL software was used to calculate the CSP volume from transabdominal multiplanar datasets of 99 structurally normal fetal ultrasound examinations between 19 and 24 weeks of gestation. Linear regression was utilized to determine reference intervals for CSP volumes as a function of gestational week (GW). Agreement among three evaluators with different proficiency levels (obstetrics and gynecology resident, perinatology fellow, and perinatologist) was assessed, using intraclass correlation coefficients (ICC) and 95% confidence intervals (CI). RESULTS: CSP volume and gestational age was positively correlated (r2=0.383, p=0.0001), represented by the following equation: 0.058-(1.016 x GW). Interobserver agreement between perinatologist and fellow was relatively high (ICC, 0.78; 95% CI, 0.70-0.85), whereas limited ultrasound experience (resident) was associated with fair agreement with non-novice observers (ICC for resident and perinatologist, 0.50; 95% CI, 0.29-0.65 and ICC for resident and fellow, 0.57; 95% CI, 0.38-0.71). CONCLUSIONS: Reference ranges of CSP volumes using VOCAL from 19 0/6 through 24 6/7 weeks of gestation were established. A first-degree model to estimate CSP volume as a function of gestational age was also constructed. CSP volumetry seems reliable when evaluated by an examiner with particular 3D sonography experience.

Adhesio interthalamica and cavum septum pellucidum in mesial temporal lobe epilepsy.

The absence of the adhesio interthalamica (AI; also called interthalamic adhesion or massa intermedia) and the presence of a large cavum septum pellucidum (CSP) later in life have been related to neurodevelopmental alterations and have not been systematically investigated in epilepsy to date. This study carried out a MRI evaluation of the AI and CSP in a large sample with mesial temporal lobe epilepsy (MTLE). A total of 179 patients, classified according to the side of the epileptogenic focus, and 156 age- and sex-balanced healthy controls were assessed. Between-group comparisons of the prevalence and length of both AI and CSP were conducted. Neuropsychological assessments were also performed in 160 MTLE patients. The patients exhibited reduction in the AI prevalence (P < 0.05; FDR-uncorrected) and length (P < 0.05; FDR-corrected) when compared to controls. Patients without AI showed lower scores in a proportion of neuropsychological tests than patients with AI. No CSP differences were found between MTLE patients and controls. These results support that AI anomalies have clinical significance in MTLE, as well as indicate that neurodevelopmental alterations may be implicated in this disorder.

Enlarged cavum septum pellucidum as a neurodevelopmental marker in adolescent-onset opiate dependence.

OBJECTIVE: Adolescent-onset exposure to highly addictive substances such as opiates may induce far-reaching deleterious effects on later mental and physical health. However, little is known about the neurodevelopmental basis for adolescent-onset opiate dependence. Here we examined whether having an abnormally large cavum septum pellucidum (CSP), a putative marker of limbic structural maldevelopment, is associated with opiate dependence particularly beginning in adolescence. METHOD: The overall length of the CSP and the prevalence of abnormal enlargement of the CSP were assessed and compared in 65 opiate-dependent subjects (41 adolescent-onset opiate users and 24 adult-onset opiate users) and 67 healthy subjects. RESULTS: Opiate-dependent subjects showed a greater prevalence of abnormal CSP enlargement relative to healthy subjects (odds ratio [OR]=3.64, p=0.034). The overall CSP length of adolescent-onset opiate-dependent subjects was greater, as compared not only with healthy subjects (F1,104=11.03, p=0.001) but also with those who began opiate use during adulthood (F1,61=4.43, p=0.039). CONCLUSIONS: The current findings provide the first evidence that abnormal CSP enlargement, which reflects limbic system dysgenesis of neurodevelopmental origin, may be linked to later development of opiate dependence. In addition, a greater CSP length, which indicates more severe limbic abnormalities, appears to confer higher risk for earlier onset of opiate use.

Postterm closure of the cavum septi pellucidi and developmental outcome in premature infants.

The authors report the natural history of closure of the cavum Septi pellucidi in premature infants 26 to 27 weeks postconception at birth and compare the developmental outcome in these infants who had closure by 42 weeks postconception to those who still had a cavum septum pellucidi visualized on ultrasound at approximately term (35-42 weeks). Of 72 patients, 35 patients still had a cavum septum pellucidi visualized on the last ultrasound done between 35 and 42 weeks postconception, and the developmental outcome of these patients was no different from those with earlier closure. The authors conclude that persistence of a cavum septi pellucidi through term is not an independent risk factor for developmental delay.

GABAB receptors in the medial septum/diagonal band slice from 16-25 day rat.

GABA(B) receptors are believed to play a role in rhythmic activity in the mammalian brain. The aim of our study was to examine the presynaptic and postsynaptic locations of these receptors in the medial septal diagonal band area (MS/DB), an area known to pace the hippocampus theta rhythm. Whole-cell patch recordings were made from parasagittal MS/DB slices obtained from the 16-25 day rat. Neurons were classified into GABAergic and cholinergic subtypes according to previous electrophysiological criteria. Bath application of the GABA(B) receptor agonist baclofen in the presence of tetrodotoxin, and brief tetanic fiber stimulation in the presence of ionotropic receptor antagonists, provided evidence for the presence of postsynaptic GABA(B) receptor transmission to GABAergic but not cholinergic neurons. Bath application of baclofen, at concentrations too low to elicit postsynaptic activity in MS/DB neurons, significantly reduced the amplitudes of stimulus-evoked ionotropic receptor inhibitory postsynaptic potentials (IPSPs) and excitatory postsynaptic potentials (EPSPs) and the paired pulse depression of these evoked potentials. Baclofen also significantly reduced the frequencies but not the amplitudes of miniature inhibitory postsynaptic currents (IPSCs) and excitatory postsynaptic currents (EPSCs), indicating the presence of presynaptic GABA(B) receptors on GABAergic and glutamatergic terminals in the MS/DB. Baclofen, also at a concentration too low to elicit postsynaptic activity, reduced the frequencies and amplitudes of spontaneous IPSCs and EPSCs recorded in the presence of 200-400 nM kainate. Rhythmic compound IPSCs at theta frequencies were recorded under these conditions in some neurons, and these rhythmic compound IPSCs were disrupted by the activation but not by the inhibition of GABA(B) receptors. These results suggest that GABA(B) receptors modulate rather than generate rhythmic activity in the MS/DB, and that this modulatory effect occurs via receptors located on presynaptic terminals.

Axotomy-induced c-JUN expression in young medial septal neurons is regulated by nerve growth factor.

In the present study we investigated the axotomy-induced expression of the proto-oncogene c-jun in young rat medial septal neurons and its regulation by nerve growth factor. First, medial septal neurons were retrogradely labelled by Fast Blue injection into the hippocampus at postnatal day 1 (P1). Rats of different developmental ages (P6, P9, P14, P21, P28 and P42) were then subjected to bilateral fimbria-fornix transection resulting in the axotomy of septohippocampal projection neurons. After the lesion, c-JUN immunoreactivity was observed in the nuclei of axotomized medial septal neurons of all stages examined, suggesting that c-JUN induction is an age-independent feature of axotomized medial septal neurons. Double immunolabelling for choline acetyltransferase and c-JUN or parvalbumin and c-JUN, respectively, revealed that both cholinergic and GABAergic septohippocampal projection neurons express c-JUN after axotomy. In addition, a co-localization of immunostaining for c-JUN and the neuropeptide galanin was found after lesion, as both proteins were induced in the same medial septal neurons following fimbria-fornix transection. Next, the regulation of c-JUN expression in axotomized medial septal neurons was studied in organotypic cultures of the medial septum. Axotomized medial septal neurons in culture did not express c-JUN in contrast to the in vivo situation. With the concept that nerve growth factor suppresses c-JUN expression, slice cultures of the medial septum were treated with antibodies against nerve growth factor. This treatment caused a dose-dependent increase in c-JUN-positive cells in these slice cultures. Simultaneous addition of nerve growth factor and antibodies against nerve growth factor resulted in the reversal of this effect. These data suggest an age-independent induction of c-JUN in axotomized medial septal neurons and its regulation by nerve growth factor.

Giant depolarizing potentials: the septal pole of the hippocampus paces the activity of the developing intact septohippocampal complex in vitro.

In neonatal hippocampal slices, recurrent spontaneous giant depolarizing potentials (GDPs) provide neuronal synchronized firing and Ca2+ oscillations. To investigate the possible role of GDPs in the synchronization of neuronal activity in intact neonatal limbic structures, we used multiple simultaneous electrophysiological recordings in the recently described preparation of intact neonatal septohippocampal complex in vitro. Combined whole-cell (in single or pairs of cells) and extracellular field recordings (one to five simultaneous recording sites) from the CA3 hippocampal region and various parts of the septum indicated that spontaneous GDPs, which can be initiated anywhere along the longitudinal hippocampal axis, are most often initiated in the septal poles of hippocampus and propagate to medial septum and temporal poles of both hippocampi simultaneously. GDPs were abolished in the medial septum but not in the hippocampus after surgical separation of both structures, suggesting hippocampal origin of GDPs. The preferential septotemporal orientation of GDP propagation observed in the intact hippocampus was associated with a corresponding gradient of GDP frequency in isolated portions of hippocampus. Accordingly, most GDPs propagated in the septotemporal direction in both septal and temporal hippocampal isolated halves, and whereas GDP frequency remained similar in the septal part of hippocampus after its surgical isolation, it progressively decreased in more temporally isolated portions of the hippocampus. Because GDPs provide most of the synaptic drive of neonatal neurons, they may modulate the development of neuronal connections in the immature limbic system.

Ontogeny of region-specific sex differences in androgen receptor messenger ribonucleic acid expression in the rat forebrain.

Testosterone and its metabolites are the principal gonadal hormones responsible for sexual differentiation of the brain. However, the relative roles of the androgen receptor (AR) vs. the estrogen receptor in specific aspects of this process remain unclear due to the intracellular metabolism of testosterone to active androgenic and estrogenic compounds. In this study, we used an 35S-labeled riboprobe and in situ hybridization to analyze steady state, relative levels of AR messenger RNA (mRNA) expression in the developing bed nucleus of the stria terminalis, medial preoptic area, and lateral septum, as well as the ventromedial and arcuate nuclei of the hypothalamus. Each area was examined on embryonic day 20 and postnatal days 0, 4, 10, and 20 to produce a developmental profile of AR mRNA expression. AR mRNA hybridization was present on embryonic day 20 in all areas analyzed. In addition, AR mRNA expression increased throughout the perinatal period in all areas examined in both males and females. However, between postnatal days 4 and 10, sharp increases in AR mRNA expression in the principal portion of the bed nucleus of the stria terminalis and the medial preoptic area occurred in the male that were not paralleled in the female. Subsequently, males exhibited higher levels of AR mRNA than females in these areas by postnatal day 10. There was no sex difference in AR mRNA content in the lateral septum, ventromedial nucleus, or arcuate nucleus at any age. These results suggest that sex differences in AR mRNA expression during development may lead to an early sex difference in sensitivity to the potential masculinizing effects of androgen.

Distribution and synaptology of dopaminergic fibers in the mature and developing lateral septum of the rat.

The dopamine innervation of the adult and developing lateral septum of the rat was investigated with light and electron microscope immunocytochemistry using anti-dopamine antibodies. Light microscopic analysis showed that the pattern of innervation of the lateral septum exhibited a marked reorganization during the first 2 postnatal weeks, when it acquired features comparable to the adult. Ultrastructural analysis suggested that there may be two different dopamine inputs in the lateral septum. The first develops earlier in life and, through symmetrical axodendritic synapses, affects remote parts of neurons and may cause inhibition. The second develops later and, through asymmetrical axosomatic synapses, affects neuronal somata and may cause excitation. These findings may explain the reported contradictory results concerning the physiological role of dopamine in neurons of the lateral septum.

Development of cholinergic and GABAergic neurons in the rat medial septum: effect of target removal in early postnatal development.

During normal development of the nervous system, the target fields influence the survival and differentiation of projection neurons, but the factors regulating this interaction remain obscure. In the present study, we have raised the question whether the target region is essential for the postnatal development and maintenance of two different types of central projection neurons, cholinergic and GABAergic septohippocampal cells. In early postnatal rats (P5, P10), the hippocampus was eliminated by unilateral intrahippocampal injections of the excitotoxin N-methyl-D-aspartate. After a long survival time (at P70), we have immunostained serial sections of the septal region with antibodies against choline acetyltransferase (ChAT), the acetylcholine-synthesizing enzyme, or the calcium-binding protein parvalbumin (PARV) which is known to be contained in GABAergic septohippocampal neurons. In the medial septum ipsilateral to the lesioned side, about 60% of ChAT-immunoreactive neurons and 62% of PARV-immunoreactive neurons were found in adulthood even after complete elimination of the hippocampus. Some immunoreactive cells appeared heavily shrunken, but electron microscopic analysis revealed ultrastructural characteristics typical for medial septal neurons obtained from controls. Our results indicate that target elimination during development affected both types of projection cells, although only the cholinergic cells are known to be responsive to target-derived factors.

Developmental expression of the NGF receptor p140trk in the septohippocampal system of the rat: a quantitative analysis.

An RNAse protection assay was used to identify p140trk mRNA in the developing rat septohippocampal system. In both the septum and hippocampus, levels of p140trk mRNA were low at birth and increased thereafter. Levels of transcripts were found to be much higher in the septum than in the hippocampus, whereas another brain region, the hypothalamus, showed levels of expression intermediate between these two structures. Only one isoform of the p140trk receptor was found to be expressed in the rat central nervous system (CNS) during development. This isoform corresponds to the one preferentially expressed in neural tissues in the adult animal. These data show that expression of the high affinity nerve growth factor (NGF) receptor is developmentally regulated during postnatal brain development and suggest that it might mediate NGF effects on developing central cholinergic systems.

Serotonergic innervation of the mature and developing lateral septum of the rat: a light and electron microscopic immunocytochemical analysis.

The serotonergic innervation of the adult and developing lateral septum of the rat was studied with immunocytochemical techniques at the light and electron microscopic levels. A few, relatively thick serotonergic fibres are found in the lateral septum at the time of birth, but they are restricted to its medial part. They subsequently extend towards the lateral ventricle, increase in number and attain their final distribution pattern by the end of the first postnatal week. Thereafter they become finer, with regularly spaced varicosities, show a higher density, and generally exhibit features, density, and pattern of innervation comparable to the adult at the end of the third postnatal week. In the dorsal portion of the lateral septum, serotonergic fibres form characteristic pericellular basket-like arrangements around cell somata and their primary dendrites. These baskets are first observed at P7, and subsequently increase both in number and in terms of the number of serotonergic terminals which they comprise. The present findings suggest that the development of serotonergic innervation of the lateral septum parallels the neuronal differentiation in this area. Ultrastructural analysis has shown that the vast majority (congruent to 95%) of serotonin varicosities make symmetrical synapses with somata, dendritic shafts and spines. These varicosities in new-born animals are in close association with neuronal elements, without any intervening neuroglial processes, but towards the end of the first postnatal week they exhibit well-defined synaptic specializations. The mean diameter of serotonergic varicosities making synapses does not change substantially with age. Serotonin-receptive neurons have several morphological features in common with the type I cells described in a previous Golgi study of the lateral septum [Alonso and Frotscher (1989) J. comp. Neurol. 286, 472-487]. Some speculations on the chemical identity of the serotonin-receptive cells have been put forward in the present study but double-labelling studies will certainly shed more light on the organization of the serotonergic innervation of the lateral septum.

Development of the rat septohippocampal projection: tracing with DiI and electron microscopy of identified growth cones.

The factors determining the development of specific fiber tracts in the central nervous system as well as the interactions of growth cones with the surrounding micromilieu are largely unknown. Here we investigated the ontogenetic development of the septohippocampal projection in the rat with the lipophilic carbocyanine dye DiI which is transported anterogradely and retrogradely in neurons and can be applied to fixed embryonic tissue. Photoconversion of anterogradely labeled fibers allowed us to study individual growth cones by electron microscopy. The first axons originating from the septal complex were found in the hippocampus as early as on embryonic day (ED) 19, reaching the fimbrial pole of the hippocampus on ED 18. However, on ED 17 we consistently found retrogradely labeled cells in the hippocampus, indicating that the development of the hippocamposeptal projection precedes that of the septohippocampal projection. On ED 19, the majority of the axons directed toward the hippocampal formation passed the hippocampus and grew further into the subicular complex and entorhinal cortex. These axons gave off collaterals that invaded the hippocampus proper. A fairly adult pattern of the septohippocampal projection was reached on postnatal day 10, although may growth cones were still found. A comparative analysis of individual growth cones found in the fimbria and the hippocampus proper revealed no striking differences in their morphology. Electron microscopic analysis showed that growth cones in the fimbria were mainly contacted by other axons, whereas growth cones in the hippocampus had contact with all available elements. This may indicate that growing septohippocampal fibers are guided by axons of the earlier formed hippocamposeptal projection. In the hippocampus proper, other cues, probably derived from the target itself, may guide the septohippocampal axons to their appropriate target cells.

[Effects of nerve growth factor on the development of the dendritic system of cholinergic neurons in dissociated culture of the rat septum]. / Deistvie faktora rosta nervov na razvitie dendritnoi sistemy kholinergicheskikh neironov v dissotsiirovannoi kul'ture septuma krys.

Neurons dissociated from septal area of fetal (E18-19) rat brain were grown 14-days in culture. Cholinergic neurons were identified by cytochemical demonstration of acetyl cholinesterase. It was shown that the nerve growth factor added to the culture medium (50 u/ml) has increased the size of cell body of AchE-positive neurons, mean total length and arborization of dendrites and also the dendritic tree area.

Effect of vasopressin administration and deficiency upon 3H-AVP binding sites in the CNS and periphery during development.

Arginine8-vasopressin (AVP, 40 micrograms/100 g b.wt., SC) was administered to male Long-Evans (LE) pups from day 1 to 7 of life and the pups were sacrificed on day 8 or 60. 3H-AVP binding was performed on membranes prepared from the liver, kidney, and septum. No significant changes were observed in the kidney or septum of animals 8 or 60 days old. However, the chronic AVP treatment did result in a significant increase in the density of 3H-AVP binding sites in the liver when compared to control day 8 pups (control 44 +/- 2 vs. AVP 56 +/- 3 fmol/mg protein), with no change in affinity. This effect was maintained into adulthood, as the day 60 AVP-treated LE rats also showed a significant increase in liver 3H-AVP binding sites compared to control (control 186 +/- 9 vs. AVP 239 +/- 14 fmol/mg protein), with no change in affinity. A comparison of 3H-AVP binding sites in 8-day-old LE, heterozygous Brattleboro (HET-BB), and homozygous Brattleboro rats (HOM-BB) was performed to assess the effect of complete (HOM-BB) and partial (HET-BB) VP deficiency on binding sites in the CNS and periphery. The liver again was the only tissue in which a change in 3H-AVP binding characteristics was noted. The HOM-BB rat (Bmax 144 +/- 6 fmol/mg protein) displayed a significant increase in AVP binding sites from the LE rat (Bmax 100 +/- 7 fmol/mg protein), while the 3H-AVP binding sites in the HET-BB rat liver (Bmax 69.8 +/- 9 fmol/mg protein) were significantly lower than LE rats. Thus hepatic AVP receptors appear most sensitive to the presence or absence of vasopressin during the early postnatal period.

Interactions between donor and host tissue following cross-species septohippocampal transplants.

Interactions between donor and host tissues following xenogeneic transplantation were studied using the neural cell surface antigen, Thy 1.2, as a marker for the donor tissue. Dissociated septal cells from Thy 1.2-positive fetal mice were transplanted to the dentate gyrus of Thy 1.2-negative adult rats. At post-transplantation survival times between 1 and 5 months, an antibody to Thy 1.2 was used to identify donor tissue. The results demonstrate that the donor tissue was capable of migrating and developing within the host following transplantation. Thy 1.2-positive cells and processes were consistently found within the supragranular, infragranular, and molecular layers of the dentate gyrus, and occasionally within the hilus, suggesting that mechanisms existed within the host which influenced the development of the transplanted tissue. Additionally, the survival and growth of the Thy 1.2-positive neurons differed from previous reports describing the growth of acetylcholinesterase (AChE)-positive fibers from xenogeneic transplants. This finding suggested that in addition to growing within the host, xenogeneic transplants may also stimulate a compensatory sprouting response from the host.

Nerve growth factor increases the intracellular content of acetylcholine in cultured septal neurons from developing rats.

The effects of nerve growth factor (NGF) on the intracellular content of acetylcholine (ACh) in cultured septal neurons from developing rats have been examined. The content of ACh could be measured by using HPLC and electrochemical detection (HPLC-ECD), coupled with an immobilized enzyme column. This method of determination is very simple and rapid, and is highly sensitive. The content of ACh and the activity of choline acetyltransferase (ChAT) in cultured postnatal day 1 (P1) septal neurons grown on an astroglial "feeder" layer was increased during the period of cultivation by the addition of NGF. The activities of ChAT and the content of ACh increased in a dose-dependent manner in direct relationship to the different amounts of NGF employed. These effects of NGF, i.e., elevating the intracellular content of ACh, accompanied by an increase in activity of ChAT, also were confirmed in the P1 septal organotypic cultures. Additionally, embryonic day 17 (E17) septal neurons in a serum-free medium displayed a similar responsiveness to NGF with respect to the elevation in the content of ACh and the increase in activity of ChAT. These results suggest that intracellular levels of ACh are likely to be regulated by NGF in a fashion similar to that of the activity levels of the biosynthetic enzyme.

NGF effects on developing forebrain cholinergic neurons are regionally specific.

Nerve growth factor (NGF) has been shown to have an effect on neurons in the central nervous system (CNS). A number of observations suggest that NGF acts as a trophic factor for cholinergic neurons of the basal forebrain and the caudate-putamen. We sought to further characterize the CNS actions of NGF by examining its effect on choline acetyltransferase (ChAT) activity in the cell bodies and fibers of developing neurons of the septum and caudate-putamen. ChAT activity was increased after even a single NGF injection. Interestingly, the magnitude of the effect of multiple NGF injections suggested that repeated treatments may augment NGF actions on these neurons. The time-course of the response to NGF was followed after a single injection on postnatal day (PD) 2. NGF treatment produced long-lasting increases in ChAT activity in septum, hippocampus and caudate-putamen. The response in cell body regions (septum, caudate-putamen) was characterized by an initial lag period of approximately 24 hr, a rapid rise to maximum values, a plateau phase and a return to baseline. The response in hippocampus was delayed by 48 hr relative to that in septum, indicating that NGF actions on ChAT were first registered in septal cell bodies. Finally, developmental events were shown to have a regionally specific influence on the response of neurons to NGF. For though the septal response to a single NGF injection was undiminished well into the third postnatal week, little or no response was detected in caudate-putamen at that time. In highlighting the potency and regional specificity of NGF effects, these observations provide additional, support for the hypothesis that NGF is a trophic factor for CNS cholinergic neurons.

Sexually dimorphic development of cholinergic enzymes in the rat septohippocampal system.

Cholinergic enzyme activity is sexually dimorphic in the rat hippocampal formation. Acetylcholinesterase (AChE) activity is greater in females than males in Ammon's horn/subiculum on the day of birth, but is equivalent in males and females at all older ages, suggesting an earlier maturation. Choline acetyltransferase (ChAT) activity also reaches adult levels earlier in female septum, and at day 18 and in adults is greater in the female dentate gyrus compared to males. Hippocampal weight relative to body weight is consistently greater in females at all ages, particularly in Ammon's horn/subiculum. Such regional sex differences during development and in adulthood suggests that cholinergic enzyme activity is regulated locally in the hippocampal target tissue.