Variations of the grid and place cells in the entorhinal cortex and dentate gyrus of 6 individuals aged 56 to 87 years

INTRODUCTION

The relationship between the entorhinal cortex (EC) and the hippocampus has been studied by different authors, who have highlighted the importance of grid cells, place cells, and the trisynaptic circuit in the processes that they regulate: the persistence of spatial, explicit, and recent memory and their possible impairment with ageing.

OBJECTIVE

We aimed to determine whether older age causes changes in the size and number of grid cells contained in layer III of the EC and in the granular layer of the dentate gyrus (DG) of the hippocampus.

METHODS

We conducted post-mortem studies of the brains of 6 individuals aged 56-87 years. The brain sections containing the DG and the adjacent EC were stained according to the Klüver-Barrera method, then the ImageJ software was used to measure the individual neuronal area, the total neuronal area, and the number of neurons contained in rectangular areas in layer III of the EC and layer II of the DG. Statistical analysis was subsequently performed.

RESULTS

We observed an age-related reduction in the cell population of the external pyramidal layer of the EC, and in the number of neurons in the granular layer of the DG.

CONCLUSION

Our results indicate that ageing causes a decrease in the size and density of grid cells of the EC and place cells of the DG.

NTS, NTSR1 and ERs in the Pituitary-Gonadal Axis of Cycling and Postnatal Female Rats after BPA Treatment

The neuropeptide neurotensin (NTS) is involved in regulating the reproductive axis and is expressed at each level of this axis (hypothalamus-pituitary-gonads). This dependence on estrogen levels has been widely demonstrated in the hypothalamus and pituitary. We focused on confirming the relationship of NTS with estrogens and the gonadal axis, using a particularly important environmental estrogenic molecule, bisphenol-A (BPA). Based on the experimental models or in vitro cell studies, it has been shown that BPA can negatively affect reproductive function. We studied for the first time the action of an exogenous estrogenic substance on the expression of NTS and estrogen receptors in the pituitary-gonadal axis during prolonged in vivo exposure. The exposure to BPA at 0.5 and 2 mg/kg body weight per day during gestation and lactation was monitored through indirect immunohistochemical procedures applied to the pituitary and ovary sections. Our results demonstrate that BPA induces alterations in the reproductive axis of the offspring, mainly after the first postnatal week. The rat pups exposed to BPA exhibited accelerated sexual maturation to puberty. There was no effect on the number of rats born per litter, although the fewer primordial follicles suggest a shorter fertile life.

Early Regressive Development of the Subcommissural Organ of Two Human Fetuses with Non-Communicating Hydrocephalus

Hydrocephalus is a central nervous system condition characterized by CSF buildup and ventricular hypertrophy. It is divided into two types: communicative and non-communicating hydrocephalus. Congenital hydrocephalus has been linked to several changes in the subcommissural organ (SCO). However, it is unclear whether these changes occur before or as a result of the hydrocephalic illness. This report presents three cases of human fetuses with hydrocephalus: one non-communicating case, two communicating cases, and two controls. Hematoxylin-Eosin (H&E) or cresyl violet and immunohistochemistry with anti-transthyretin were used to analyze SCO morphological and secretory changes. We conclude that in the cases presented here, there could be an early regression in the SCO of the communicating cases that is not present in the non-communicating case.

AQP4 labels a subpopulation of white matter-dependent glial radial cells affected by pediatric hydrocephalus, and its expression increased in glial microvesicles released to the cerebrospinal fluid in obstructive hydrocephalus

Hydrocephalus is a distension of the ventricular system associated with ventricular zone disruption, reactive astrogliosis, periventricular white matter ischemia, axonal impairment, and corpus callosum alterations. The condition's etiology is typically attributed to a malfunction in classical cerebrospinal fluid (CSF) bulk flow; however, this approach does not consider the unique physiology of CSF in fetal and perinatal patients. The parenchymal fluid contributes to the glymphatic system, and plays a fundamental role in pediatric hydrocephalus, with aquaporin 4 (AQP4) as the primary facilitator of these fluid movements. Despite the importance of AQP4 in the pathophysiology of hydrocephalus, it’s expression in human fetal life is not well-studied. This manuscript systematically defines the brain expression of AQP4 in human brain development under control (n = 13) and hydrocephalic conditions (n = 3). Brains from 8 postconceptional weeks (PCW) onward and perinatal CSF from control (n = 2), obstructive (n = 6) and communicating (n = 6) hydrocephalic samples were analyzed through immunohistochemistry, immunofluorescence, western blot, and flow cytometry. Our results indicate that AQP4 expression is observed first in the archicortex, followed by the ganglionic eminences and then the neocortex. In the neocortex, it is initially at the perisylvian regions, and lastly at the occipital and prefrontal zones. Characteristic astrocyte end-feet labeling surrounding the vascular system was not established until 25 PCW. We also found AQP4 expression in a subpopulation of glial radial cells with processes that do not progress radially but, rather, curve following white matter tracts (corpus callosum and fornix), which were considered as glial stem cells (GSC). Under hydrocephalic conditions, GSC adjacent to characteristic ventricular zone disruption showed signs of early differentiation into astrocytes which may affect normal gliogenesis and contribute to the white matter dysgenesis. Finally, we found that AQP4 is expressed in the microvesicle fraction (p < 0.01) of CSF from patients with obstructive hydrocephalus. These findings suggest the potential use of AQP4 as a diagnostic and prognostic marker of pediatric hydrocephalus and as gliogenesis biomarker.

Disproportion in Pericyte/Endothelial Cell Proliferation and Mechanisms of Intussusceptive Angiogenesis Participate in Bizarre Vessel Formation in Glioblastoma

Glioblastoma (GBM) is the most malignant tumor in the brain. In addition to the vascular pattern with thin-walled vessels and findings of sprouting angiogenesis, GBM presents a bizarre microvasculature (BM) formed by vascular clusters, vascular garlands, and glomeruloid bodies. The mechanisms in BM morphogenesis are not well known. Our objective was to assess the role of pericyte/endothelial proliferation and intussusceptive angiogenic mechanisms in the formation of the BM. For this purpose, we studied specimens of 66 GBM cases using immunochemistry and confocal microscopy. In the BM, the results showed (a) transitional forms between the BM patterns, mostly with prominent pericytes covering all the abluminal endothelial cell (EC) surface of the vessels, (b) a proliferation index high in the prominent pericytes and low in ECs (47.85 times higher in pericytes than in ECs), (c) intravascular pillars (hallmark of intussusceptive angiogenesis) formed by transcapillary interendothelial bridges, endothelial contacts of opposite vessel walls, and vessel loops, and (d) the persistence of these findings in complex glomeruloid bodies. In conclusion, disproportion in pericyte/EC proliferation and mechanisms of intussusceptive angiogenesis participate in BM formation. The contributions have morphogenic and clinical interest since pericytes and intussusceptive angiogenesis can condition antiangiogenic therapy in GBM.

Variations of the grid and place cells in the entorhinal cortex and dentate gyrus of 6 individuals aged 56 to 87 years

INTRODUCTION

The relationship between the entorhinal cortex and the hippocampus has been studied by different authors, who have highlighted the importance of grid cells, place cells, and the trisynaptic circuit in the processes that they regulate: the persistence of spatial, explicit, and recent memory and their possible impairment with ageing.

OBJECTIVE

We aimed to determine whether older age causes changes in the size and number of grid cells contained in layer III of the entorhinal cortex and in the granular layer of the dentate gyrus of the hippocampus.

METHODS

We conducted post-mortem studies of the brains of 6 individuals aged 56-87 years. The brain sections containing the dentate gyrus and the adjacent entorhinal cortex were stained according to the Klüver-Barrera method, then the Image J software was used to measure the individual neuronal area, the total neuronal area, and the number of neurons contained in rectangular areas in layer III of the entorhinal cortex and layer II of the dentate gyrus. Statistical analysis was subsequently performed.

RESULTS

We observed an age-related reduction in the cell population of the external pyramidal layer of the entorhinal cortex, and in the number of neurons in the granular layer of the dentate gyrus.

CONCLUSION

Our results indicate that ageing causes a decrease in the size and density of grid cells of the entorhinal cortex and place cells of the dentate gyrus.

A Distal to Proximal Gradient of Human Choroid Plexus Development, with Antagonistic Expression of Glut1 and AQP1 in Mature Cells vs. Calbindin and PCNA in Proliferative Cells

The choroid plexuses (ChP) are highly vascularized tissues suspended from each of the cerebral ventricles. Their main function is to secret cerebrospinal fluid (CSF) that fills the ventricles and the subarachnoid spaces, forming a crucial system for the development and maintenance of the CNS. However, despite the essential role of the ChP–CSF system to regulate the CNS in a global manner, it still remains one of the most understudied areas in neurobiology. Here we define by immunohistochemistry the expression of different proteins involved in the maturation and functionality of the ChP from the late embryological period to maturity. We found an opposite gradient of expression between aquaporin 1 (AQP1) and glucose transporter 1 (Glut 1) that define functional maturation in the ChP periphery, and proliferating cell nuclear antigen (PCNA) and calbindin (CB), present in the ChP root zone with proliferative activity. We conclude that the maturation of the ChP matures from distal to proximal, starting in the areas nearest to the cortex, expressing in the distal, mature areas AQP1 and Glut1 (related to ChP functionality to support cortex development), and in the proximal immature areas (ChP root) CB and PCNA related to progenitor activity and proliferation.

Cerebrospinal fluid levels of tumor necrosis factor alpha and aquaporin 1 in patients with mild cognitive impairment and idiopathic normal pressure hydrocephalus

OBJECTIVE

The aim of the present work was to make a comparative analysis of the cerebrospinal fluid levels of Tumor necrosis factor (TNFα) and aquaporin 1 (AQP1) in (i) healthy elder control, (ii) patients with mild cognitive impairment and, (iii) patients with idiopathic normal pressure hydrocephalus.

PATIENTS AND METHODS

Samples of CSF were taken from seven patients with MCI, 77 years average age; six patients with iNPH, 75 years average age; eleven healthy subjects, 60year average age, were used as controls. The cerebrospinal fluid levels of AQP1 and TNFα were studied by enzyme immunoassay (ELISA).

RESULTS

In mild cognitive impairment the total protein content of the CSF and the relative CSF levels of AQP1 and TNFα were similar to those of control subjects and different from those of iNPH patients. On the other hand, in iNPH patients the CSF content of proteins was low and the levels of TNFα were significantly high while those of AQP1 were insignificantly high.

CONCLUSION

These finding may help the differential diagnosis and prognosis of mild cognitive impairment and normal pressure hydrocephalus patients.

Choroid plexus dysfunction impairs beta-amyloid clearance in a triple transgenic mouse model of Alzheimer's disease

Compromised secretory function of choroid plexus (CP) and defective cerebrospinal fluid (CSF) production, along with accumulation of beta-amyloid (Aβ) peptides at the blood-CSF barrier (BCSFB), contribute to complications of Alzheimer’s disease (AD). The AD triple transgenic mouse model (3xTg-AD) at 16 month-old mimics critical hallmarks of the human disease: β-amyloid (Aβ) plaques and neurofibrillary tangles (NFT) with a temporal- and regional- specific profile. Currently, little is known about transport and metabolic responses by CP to the disrupted homeostasis of CNS Aβ in AD. This study analyzed the effects of highly-expressed AD-linked human transgenes (APP, PS1 and tau) on lateral ventricle CP function. Confocal imaging and immunohistochemistry revealed an increase only of Aβ42 isoform in epithelial cytosol and in stroma surrounding choroidal capillaries; this buildup may reflect insufficient clearance transport from CSF to blood. Still, there was increased expression, presumably compensatory, of the choroidal Aβ transporters: the low density lipoprotein receptor-related protein 1 (LRP1) and the receptor for advanced glycation end product (RAGE). A thickening of the epithelial basal membrane and greater collagen-IV deposition occurred around capillaries in CP, probably curtailing solute exchanges. Moreover, there was attenuated expression of epithelial aquaporin-1 and transthyretin (TTR) protein compared to Non-Tg mice. Collectively these findings indicate CP dysfunction hypothetically linked to increasing Aβ burden resulting in less efficient ion transport, concurrently with reduced production of CSF (less sink action on brain Aβ) and diminished secretion of TTR (less neuroprotection against cortical Aβ toxicity). The putative effects of a disabled CP-CSF system on CNS functions are discussed in the context of AD.

Aquaporin-4 expression in the cerebrospinal fluid in congenital human hydrocephalus

Background

Aquaporin-4 (AQP4) is a water channel mainly located in the ventricular ependymal cells (brain-CSF barrier), the sub-ependymal glia, glia limitans and in end-feet of astrocytes in at the blood–brain barrier (BBB).

Methods

In the present work, the expression of AQP4 in the cerebrospinal fluid (CSF) in control and congenital human hydrocephalus infants (obstructive and communicating), was analysed by Western-blot and enzyme immunoassay (ELISA).

Results

AQP4 was found to be high compared to the control in the CSF in congenital hydrocephalus patients. Western-blot showed higher values for AQP4 than controls in communicating hydrocephalus (communicating: 38.3%, control: 6.9% p < 0.05) although the increase was not significant in obstructive hydrocephalus (obstructive: 14.7%). The AQP4 quantification by ELISA also showed that, the mean concentration of AQP4 in CSF was significantly higher in communicating hydrocephalus (communicating: 11.32 ± 0.69 ng/ml, control: 8.61 ± 0.31 ng/ml; p < 0.05). However, there was no increase over control in obstructive hydrocephalus (obstructive: 8.65 ± 0.80 ng/ml).

Conclusions

AQP4 has a modulatory effect on ependyma stability and acts in CSF production and reabsorption. Therefore, the increase of AQP4 in the CSF in congenital hydrocephalus could be due to the fact that AQP4 passes from the parenchyma to the CSF and this AQP4 movement may be a consequence of ependyma denudation.

The expression of p73 in the organum vasculosum of the lamina terminalis and choroid plexus of spontaneously hypertensive rats

The p73 proteins are present in different kinds of cells of the central nervous system, such as the choroid plexus, circumventricular structures and neuroepithelium. It has been reported that spontaneously hypertensive rats show ventricular dilation, changes in cerebrospinal fluid proteins and variations in the circumventricular structures such as the organum vasculosum of the lamina terminalis and the choroid plexus, which are altered in ventricular dilation. The aim of the present work is to study p73 expression in the organum vasculosum of the lamina terminalis and the choroid plexus and its variations in high blood pressure. Brains from control Wistar-Kyoto rats and spontaneously hypertensive rats were used. The organum vasculosum of the lamina terminalis and the choroid plexus were processed by immunohistochemistry and western blot with anti-TAp73. We found weaker markings in the organum vasculosum of the lamina terminalis and stronger markings in the choroid plexus of the hypertensive than the control rats. Therefore, hypertension in the spontaneously hypertensive rats produces alterations in choroid plexus protein p73 expression that is similar to that described for other circumventricular organs, but it is different in the organum vasculosum of the lamina terminalis. We can conclude that the functional balance between p73, organum vasculosum of the lamina terminalis and choroid plexus, which is probably necessary to maintain the normal functioning of these structures, is altered by the hypertension found in these rats.

Luteinizing hormone-releasing hormone distribution in the anterior hypothalamus of the female rats

Luteinizing hormone-releasing hormone (LHRH) neurons and fibers are located in the anteroventral hypothalamus, specifically in the preoptic medial area and the organum vasculosum of the lamina terminalis. Most luteinizing hormone-releasing hormone neurons project to the median eminence where they are secreted in the pituitary portal system in order to control the release of gonadotropin. The aim of this study is to provide, using immunohistochemistry and female brain rats, a new description of the luteinizing hormone-releasing hormone fibers and neuron localization in the anterior hypothalamus. The greatest amount of the LHRH immunoreactive material was found in the organum vasculosum of the lamina terminalis that is located around the anterior region of the third ventricle. The intensity of the reaction of LHRH immunoreactive material decreases from cephalic to caudal localization; therefore, the greatest immunoreaction is in the organum vasculosum of the lamina terminalis, followed by the dorsomedial preoptic area, the ventromedial preoptic area, and finally the ventrolateral medial preoptic area, and in fibers surrounding the suprachiasmatic nucleus and subependymal layer on the floor of the third ventricle where the least amount immunoreactive material is found.

Reissner's fibre proteins and p73 variations in the cerebrospinal fluid and subcommissural organ of hydrocephalic rat

Reissner's fibre (RF) is formed by the polymerization of the glycoprotein secreted by the subcommissural organ (SCO). The SCO also secretes soluble glycoprotein into the cerebrospinal fluid (CSF); variations in RF and SCO have been reported in hydrocephalus. On the other hand, hydrocephalus and other brain alterations have been described in p73 mutant mice. The p73 belongs to the tumour suppressor p53 protein family and has two isoforms: the TAp73 with apoptotic activity and DeltaNp73 with anti-apoptotic function. Moreover, the TAp73 isoform is glycosylated and secreted into the CSF. In the present work, we analysed the variations in RF and p73 proteins in the CSF and SCO of spontaneously hydrocephalic rats. Brains from control rats and spontaneously hydrocephalic rats of 12 months of age were used. The SCO sections were immunohistochemically processed with anti-TAp73 and anti-Reissner fibre (AFRU). The spontaneous hydrocephalus presents a decrease in the AFRU immunoreactive material in the SCO and an absence of RF. The anti-TAp73 was also present, slightly decreased, in the hydrocephalic SCO. AFRU and p73 bands were also detected in the CSF by western blot and six AFRU and p73 protein bands of a similar molecular weight were found in the CSF of the control rats. The number of AFRU and p73 bands was lower in the hydrocephalic rats than in the control rats. In conclusion, hydrocephalus produces a decrease in the secretions of the SCO and an absence of RF and a decrease in p73 and RF proteins in the CSF.

Expression of certain proteins in the subfornical organ and cerebrospinal fluid of spontaneously hypertensive rats

The objective of this study was to analyze the proteins in the cerebrospinal fluid of spontaneously hypertensive rats and to study their possible role in the relationship between hydrocephalus, arterial hypertension and variations in the subfornical organ. Brains and cerebrospinal fluid from control Wistar-Kyoto rats and spontaneously hypertensive rats sacrificed with chloral hydrate were used. Cerebrospinal fluid and extract of subfornical organ were processed by protein electrophoresis. Antisera against protein bands of 141, 117 and 48 kDa and Concanavalin A were used for immunohistochemical and western blot study of the subfornical organ, adjacent circumventricular structures and cerebrospinal fluid. Ventricular dilation in the spontaneously hypertensive rats and the presence of quite a lot of protein bands in the cerebrospinal fluid of the hypertensive rats, which were either not observed or scarcely present in the cerebrospinal fluid of the Wistar-Kyoto rats, were confirmed. The subfornical organ, third ventricle ependyma and choroideus plexus showed immunoreactive material for antibodies against 141kDa, 117 and 48 kDa proteins band (anti-B1, anti-B2 and anti-B3). The larger amount of the immunoreactive material was found in the subfornical organ of the spontaneously hypertensive rat. Our results and the alterations observed by other authors in the subfornical organ in hydrocephalic and hypertensive rats support the possibility that this circumventricular organ, some proteins of the cerebrospinal fluid and ventricular dilation could be connected with the physiopathology of this type of hypertension.

Alterations of the cerebrospinal fluid proteins and subcommissural organ secretion in the arterial hypertension and ventricular dilatation. A study in SHR rats

The aim of this work was to analyze the proteins in the cerebrospinal fluid (CSF) of spontaneously hypertensive rats, to study their possible role in the relationship between hydrocephalus, arterial hypertension and alterations in the subcommissural organ. Brains from control Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) sacrificed with chloral hydrate were used. Antiserums against some cerebrospinal fluid protein bands and Reissner's fiber (RF) were used for immunohistochemical study of the SCO. Ventricular dilation was observed in the lateral and third ventricle of the SHR. Third ventricle ependyma showed immunoreactive material (IRM) for antibody against 141 kDa protein band anti-B1 and 117 protein band anti-B2 and the SCO of the SHR showed a decrease of the IRM when compared with WKY rats. An alteration in the expression of anti-RF was found to compare the SCO of the WKY and SHR groups. Our results demonstrate that hydrocephalus and hypertension are interconnected in this kind of rat which produce alterations in SCO secretions and some proteins of the CSF.

Postnatal Development of the Secretory Activity of the Goat Subcommissural Organ. A Reissner's Fibre and Angiotensin II Immunohistochemical Study

Subcommissural organ (SCO) secretory activity of the goat (variations of Capra hircus, that live in arid conditions) was examined during the postnatal development, using specific antibodies against the Reissner's fibre (AFRU) and angiotensin II (AAGII). The SCO was strongly stained with the anti-glycoproteins that form the Reissner's fibre and lightly marked with the anti-angiotensin II. The AFRU-immunoreactivity (ir) was found in the ependymal and hypendymal cells and in the ventricular and peripheral secretory routes of the goat SCO. The amount AFRU increases at 6 months and decreases at adult age. In contrast, the anti-angiotensin II-ir was mainly found in the adult age, not being practically observed at one postnatal month. The AAGII-ir was mainly found in ependymal cells in which AFRU-ir was downregulated. In addition, we detected the presence of double immunostained for AFRU and AAGII in ependymocytes of the pre-commissural and subcommissural parts. In conclusion the present results may suggest a functional interrelation between AAGII and the secretory activity of the SCO of this kind of goat.