During hypothalamic development, the germinative neuroepithelium gives birth to diverse neural cells that regulate numerous physiological functions in adulthood.

Colloid cyst treatment with purely endoscopic surgery is considered to be safe and effective. Complete capsule removal for gross total resection is usually recommended to prevent recurrence but may not always be safely feasible. Our objective was to assess the results of endoscopic surgery using mainly aspiration and coagulation without complete capsule resection and discuss the rationale for the procedure.

Many of the clinical and neuroendocrine features of bipolar disorder involve hypothalamic structures. Although current neuroimaging techniques inadequately resolve the structural components of the hypothalamus, evidence of derangement can be sought by examining the adjacent third ventricle and the functionally related pituitary.

Endoscopic methods have gained a well-established position in surgical treatment of colloid cysts of third ventricle. However, the possibility of total tumor removal with this method and the long-term effectiveness of treatment are being questioned.

Neural transplants into the third ventricle utilized to quantitatively assess the effectiveness of fetal tissue from selected brain sites in restoring circadian locomotor rhythmicity of adult hamsters rendered arrhythmic by lesions of the suprachiasmatic nuclei (SCN). Circadian function was continuously monitored in recording wheel cages under controlled environmental conditions. Animals which remained arrhythmic for 3-4 weeks after SCN lesions received transplants of neural tissue from 13-14-day-old fetuses: either SCN tissue or non-SCN tissue (cerebral cortex or hypothalamus excluding SCN). Quantitative evaluation of the data indicated partial restoration of circadian rhythmicity in 37% of 19 animals with SCN transplants, but in 0% of the 9 animals with non-SCN neural transplants. The mean time for reappearance of rhythmicity was 20 days after SCN transplantation. Animals were sacrificed 8-10 weeks after transplantation for histological analysis in order to visualize lesion placement and to characterize transplants. The cytoarchitecture and neuropeptide organization of the transplants were consistent with the brain region. Only SCN transplants were characterized by aggregates of small neurons with codistributed immunoreactivity for SCN-characteristic neuropeptides.

Rats and mice exposed to repeated stress or a single severe stress exhibit a sustained increase in energetic, endocrine, and behavioral response to subsequent novel mild stress. This study tested whether the hyper-responsiveness was due to a lowered threshold of response to corticotropin releasing factor (CRF) or an exaggerated response to a standard dose of CRF. Male Sprague-Dawley rats were subjected to 3h of restraint on each of 3 consecutive days (RRS) or were non-restrained controls. RRS caused a temporary hypophagia but a sustained reduction in body weight. Eight days after the end of restraint, rats received increasing third ventricle doses of CRF (0-3.0μg). The lowest dose of CRF (0.25μg) increased corticosterone release in RRS, but not control rats. Higher doses caused the same stimulation of corticosterone in the two groups of rats. Fifteen days after the end of restraint, rats were food deprived during the light period and received increasing third ventricle doses of CRF at the start of the dark period. The lowest dose of CRF inhibited food intake during the first hour following infusion in RRS, but not control rats. All other doses of CRF inhibited food intake to the same degree in both RRS and control rats. The lowered threshold of response to central CRF is consistent with the chronic hyper-responsiveness to CRF and mild stress in RRS rats during the post-restraint period.

Chordoid glioma is a rare brain tumor thought to arise from specialized glial cells of the lamina terminalis along the anterior wall of the third ventricle. Despite being histologically low-grade, chordoid gliomas are often associated with poor outcome, as their stereotypic location in the third ventricle makes resection challenging and efficacious adjuvant therapies have not been developed. Here we performed genomic profiling on 13 chordoid gliomas and identified a recurrent D463H missense mutation in PRKCA in all tumors, which localizes in the kinase domain of the encoded protein kinase C alpha (PKCα). Expression of mutant PRKCA in immortalized human astrocytes led to increased phospho-ERK and anchorage-independent growth that could be blocked by MEK inhibition. These studies define PRKCA as a recurrently mutated oncogene in human cancer and identify a potential therapeutic vulnerability in this uncommon brain tumor.

Although cavernous hemangiomas (CHs) can be found anywhere in the central nervous system, CHs of the third ventricle have been reported in only 29 patients (including our case). In the current case report, we discuss the clinical characteristics and surgical outcome of CHs of the third ventricle.

Feeding behavior and energy metabolism are precisely regulated by humoral and/or neural factors in the central nervous system. In particular, nuclei, such as the arcuate nucleus, ventromedial hypothalamic nucleus, and lateral hypothalamic area located near the third ventricle of the hypothalamus are the centers of feeding and energy metabolism in various vertebrate species, including chickens. In this study, we evaluated the effects of cannulation of the third ventricle on chick growth and feeding behavior in the neonatal stage, to develop a method for local and chronic central nervous system-mediated energy metabolism. Referring to the chick brain atlas, a guide cannula was inserted into the third ventricle of the chick under anesthesia immediately after hatching using a stereotaxic instrument. The chicks that recovered from anesthesia were bred for 11 days under normal feeding management conditions, and then feed intake amount, body weight gain, and metabolic tissue weight were measured. The effects of direct stimulation of the third ventricle with 2-deoxy-D-glucose on the expression level of the immediate-early gene, cFOS, and feed intake in 5-day-old chicks were also evaluated. There were no differences in feed intake, body weight gain, and metabolic tissue weight between 11-day-old cannulated and control chicks. The expression of cFOS mRNA in the ventromedial hypothalamic nucleus was higher than that in the amygdala after the third ventricular administration of 2-deoxy-D-glucose. Additionally, direct third ventricular injection of 2-deoxy-D-glucose attenuated the feeding behavior of chicks for a while. Overall, we speculate that the technique is effective for local and/or chronic stimulation of the nucleus near the third ventricle of the chick hypothalamus, which is important for feed and energy metabolism regulation.

Interleukin (IL)-6- /- mice develop mature onset obesity, whereas i.c.v. injection of IL-6 decreases obesity in rodents. Moreover, levels of IL-6 in cerebrospinal fluid (CSF) were reported to be inversely correlated with obesity in humans. Tanycytes lining the base of the third ventricle (3V) in the hypothalamus have recently been reported to be of importance for metabolism. In the present study, we investigated whether tanycytes could respond to IL-6 in the CSF. With immunohistochemistry using a well characterised antibody directed against the ligand binding receptor for IL-6, IL-6 receptor α (IL-6Rα), it was found that tanycytes, identified by the two markers, vimentin and dopamine- and cAMP-regulated phosphoprotein of 32 kDa, contained IL-6Rα. There were fewer IL-6Rα on another type of ventricle-lining cells, ependymal cells, as identified by the marker glucose transporter-1. To demonstrate that the immunoreactive IL-6Rα were responsive to IL-6, we injected IL-6 i.c.v. This treatment increased immunoreactive phosphorylated signal transducer and activator of transcription-3 (pSTAT3) in tanycytes after 5 minutes and in cells in the medial part of the arcuate nucleus after 5 and 15 minutes. Intracerebroventricular injection of leptin exerted similar effects. As expected, i.p. injection of leptin also induced pSTAT3 staining in the hypothalamus, whereas i.p. IL-6 injection had little effect on this parameter. Intracerebroventricular or i.p. injection of vehicle only had no effect on pSTAT3-immunoreactivity. In summary, there are functional IL-6Rα on tanycytes at the bottom of the 3V, in agreement with the possibility that ventricular administration of IL-6 decreases obesity in mice via an effect on this cell type.

To test the hypothesis that prepubertal exposure of LHRH neurons to a source of catecholamines and neuropeptides accelerates the onset of puberty, we examined the effects of autologous adrenal transplantation into the base of the third ventricle of the brain in juvenile female rhesus monkeys at 11-13 months of age. The adrenal medulla, which contains catecholamines and neuropeptide Y (NPY), was cut into small pieces and mixed with gelfoam in artificial CSF and injected into the third ventricle, adjacent to LHRH neurons and their neuroterminals. Sham control monkeys received artificial CSF with gelfoam alone. Animals were monitored for signs of pubertal development. While menarche was not altered by adrenal transplantation, the timing of first and second ovulations occurred significantly (P < 0.05) earlier in adrenal-transplanted monkeys. Histological examination indicated that the grafts survived in all transplanted monkeys. The presence of catecholamines and NPY in graft tissue was confirmed by tyrosine-hydroxylase-positive, dopamine beta-hydroxylase-positive, and NPY-positive cells. Endogenous LHRH fibers were observed innervating the graft tissue. We conclude that: (1) adrenal medulla transplantation into the third ventricle accelerates the age of first ovulation; (2) this is likely due to neuroactive substances (e.g., catecholamines and NPY) from the graft tissue; and (3) grafted adrenal medulla tissue can survive for at least 30-40 months. However, the age of menarche was not accelerated by this grafting, suggesting that an additional mechanism (e.g., removal of tonic inhibition) may be necessary for the onset of puberty.

A single central injection of angiotensin II (AngII) potently increases water intake; however, a growing body of research suggests that repeated, acute intracerebroventricular injections of AngII cause a reduction in the dipsogenic response to subsequent AngII. This AngII-induced behavioral desensitization is specific to the effects of angiotensin and mediated by the angiotensin type-1 (AT1) receptor. The neuroanatomical substrate for this phenomenon, however, remains unknown. The anteroventral third ventricle (AV3V) region is an important site for the behavioral and physiological actions of AngII. Therefore, we hypothesized that this region also mediates the effects of repeated central AngII administration. In support of this hypothesis, we found that repeated injections of AngII into the AV3V reduced water intake stimulated by a test injection of AngII given into this region. Moreover, repeated AngII injections in the AV3V reduced water intake after AngII was injected into the lateral ventricle. These studies also demonstrate that activation of the AT1 receptor within the AV3V is required for AngII-induced behavioral desensitization because direct injection of the AT1 receptor antagonist, losartan, into the AV3V blocked the desensitizing effect of repeated AngII injections into the lateral ventricle. These findings provide additional support for a role of the AV3V in the dipsogenic actions of AngII, and suggest that this region is critical for the desensitization that occurs after acute repeated central injections of AngII.

This study demonstrates glial and gliovascular markers of organon vasculosum laminae terminalis (OVLT) in three planes. The distribution of glial markers displayed similarities to the subfornical organ. There was an inner part with vimentin- and nestin-immunopositive glia whereas GFAP and the water-channel aquaporin 4 were found at the periphery. This separation indicates different functions of the two regions. The presence of nestin may indicate stem cell-capabilities whereas aquaporin 4 has been reported to promote the osmoreceptor function. Glutamine synthetase immunoreactivity was sparse like in the area postrema and subfornical organ. The laminin and β-dystroglycan immunolabelings altered along the vessels such as in the subfornical organ indicating altering gliovascular relations. The different subdivisions of OVLT received glial processes of different origins. The posterior periventricular zone contained short vimentin-immunopositive processes from the ependyma of the adjacent surface of the third ventricle. The lateral periventricular zone received forceps-like process systems from the anterolateral part of the third ventricle. Most interestingly, the "dorsal cap" received a mixed group of long GFAP- and vimentin-immunopositive processes from a distant part of the third ventricle. The processes may have two functions: a guidance for newly produced cells like radial glia in immature brain and/or a connection between distant parts of the third ventricle and OVLT.

The subventricular zone of the third ventricle (TVZ) is a germinal stem cell niche, identified as the possible location of optic pathway glioma (OPG) cell origin. Paediatric OPGs are predominantly diagnosed as low-grade astrocytomas, which are either sporadic or are associated with neurofibromatosis type-1 (NF1). These tumours often cause a significant impairment to visual acuity (VA). Infiltrative/invasive tumour activity is associated with increased apparent diffusion coefficient (ADC) and cerebral blood flow (CBF). This study aimed to determine whether TVZ imaging features differed between sporadic-OPG, NF1-OPG and controls, and whether the ADC and CBF profile at the germinal stem cell niche (the TVZ) correlated with the primary outcome of VA.

Third ventricular meningiomas are exceedingly rare intracranial tumors that may present with intraventricular hemorrhage.

This investigation has confronted some very basic questions of neurobiology and specifically deals with the neurovascular and neuroanatomical interactions that occur between graft and host following neural transplantation. Host Long-Evans rats with chronic autosomal diabetes insipidus (DI) received stereotaxic implants of normal 17 day post-coitus fetal hypothalamic fragments from the rostral (anterior) hypothalamus of normal Long-Evans pups. Following stereotaxic surgery DI hosts were killed 60 or 90 days later and their brain prepared for correlative microangiography-immunocytochemistry coupled with transmission electron microscopy. Explants were rapidly invaded by host vessels from several routes. (1) Vessels appeared to arise from portal capillaries in the underlying median eminence and (2) from adjacent vessels from the paraventricular nucleus and surrounding endocrine hypothalamus and (3) possibly from intrinsic vessels of the graft. The former remained fenestrated and established bonafide neurovascular zones in the ventral regions and in actively growing explants. Small clusters of arginine vasopressin-positive fibers and neurophysin positive neurons were noted throughout the parenchyma of explants. Despite the presence of neurosecretory neurons and neurovascular (neurohemal) zones, none of the host rats exhibited a physiological return to normal parameters of water balance. However the active growth and development of explants in the third cerebral ventricle of DI host rats coupled with emergence of neurovascular zones lends support to a potential model for analyzing the development of anatomical substrates for the central delivery of neuropeptide hormones.

The walls of the third ventricle have been proposed to serve as a bidirectional conduit for exchanges between the neural parenchyma and the cerebrospinal fluid. In immunohistochemical studies of mice, we observed that light exposure and circadian phase affected peptide staining surrounding the third ventricle at the level of the suprachiasmatic nuclei. Under high magnification, we observed robust staining for the neurohormone oxytocin and the calcium-binding protein parvalbumin associated with cilia extending into the third ventricle from the surrounding ventricular wall; no similar staining was observed for vasopressin or calbindin. Retinal illumination had opposite effects on levels of parvalbumin and oxytocin in the cilia: light exposure during late subjective night increased oxytocin staining, but decreased parvalbumin staining in the cilia. Preventing cellular transport with colchicine eliminated immunohistochemical staining for oxytocin in the cilia. There was also a significant daily rhythm of oxytocin immunostaining in the third ventricle wall, and in magnocellular neurons in the anterior hypothalamus. The results suggest that environmental lighting and circadian rhythms regulate levels of oxytocin in the cerebrospinal fluid, possibly by regulating movement of oxytocin through the third ventricle wall.

There is a disagreement in the literature concerning the degree of proliferation of cells in the walls of the third ventricle (3rdV) under normal conditions in the adult mammalian brain. To address this issue, we mapped the cells expressing the neural stem/progenitor cell marker nestin along the entire rostrocaudal extent of the 3rdV in adult male rats and observed a complex distribution. Abundant nestin was present in tanycyte cell bodies and processes and also was observed in patches of ependymal cells as well as in isolated ependymal cells throughout the walls of the 3rdV. However, we observed very limited ependymal cell or tanycyte proliferation in normal adult rats as determined by bromodeoxyuridine (BrdU) incorporation or the expression of Ki-67. Moreover, fewer than 13% of the cells that were BrdU-positive (BrdU+) or Ki-67-positive (Ki-67+) expressed nestin. These observations stand in contrast to those made in the subventricular zone of the lateral ventricle (SVZ) and subgranular zone of the hippocampal formation (SGZ), where cell proliferation measured by BrdU incorporation or Ki-67 expression is observed frequently in cells that also express nestin. Thus, while ependymal cell or tanycyte cell proliferation can be promoted by the addition of mitogens, dietary modifications or other in vivo manipulations, the proliferation of ependymal cells and tanycytes in the walls of the 3rdV is very limited in the normal adult male rat brain.

The volume, composition, and movement of the cerebrospinal fluid (CSF) are important for brain physiology, pathology, and diagnostics. Nevertheless, few studies have focused on the main structure that produces CSF, the choroid plexus (CP). Due to the presence of monocarboxylate transporters (MCTs) in the CP, changes in blood and brain lactate levels are reflected in the CSF. A lactate receptor, the hydroxycarboxylic acid receptor 1 (HCA1), is present in the brain, but whether it is located in the CP or in other periventricular structures has not been studied. Here, we investigated the distribution of HCA1 in the cerebral ventricular system using monomeric red fluorescent protein (mRFP)-HCA1 reporter mice. The reporter signal was only detected in the dorsal part of the third ventricle, where strong mRFP-HCA1 labeling was present in cells of the CP, the tela choroidea, and the neuroepithelial ventricular lining. Co-labeling experiments identified these cells as fibroblasts (in the CP, the tela choroidea, and the ventricle lining) and ependymal cells (in the tela choroidea and the ventricle lining). Our data suggest that the HCA1-containing fibroblasts and ependymal cells have the ability to respond to alterations in CSF lactate in body-brain signaling, but also as a sign of neuropathology (e.g., stroke and Alzheimer's disease biomarker).

The third ventricle (3 V) wall of the tuberal hypothalamus is composed of two types of cells; specialized ependymoglial cells called tanycytes located ventrally and ependymocytes dorsally, which control the exchanges between the cerebrospinal fluid and the hypothalamic parenchyma. By regulating the dialogue between the brain and the periphery, tanycytes are now recognized as central players in the control of major hypothalamic functions such as energy metabolism and reproduction. While our knowledge of the biology of adult tanycytes is progressing rapidly, our understanding of their development remains very incomplete. To gain insight into the postnatal maturation of the 3 V ependymal lining, we conducted a comprehensive immunofluorescent study of the mouse tuberal region at four postnatal ages (postnatal day (P) 0, P4, P10, and P20). We analyzed the expression profile of a panel of tanycyte and ependymocyte markers (vimentin, S100, connexin-43 [Cx43], and glial fibrillary acidic protein [GFAP]) and characterized cell proliferation in the 3 V wall using the thymidine analog bromodeoxyuridine. Our results show that most changes in marker expression occur between P4 and P10, with a switch from a 3 V mostly lined by radial cells to the emergence of a tanycytic domain ventrally and an ependymocytic domain dorsally, a drop in cell proliferation and increased expression of S100, Cx43, and GFAP that acquire a mature profile at P20. Our study thus identifies the transition between the first and the second postnatal week as a critical time window for the postnatal maturation of the 3 V wall ependymal lining.