Neuroprotein dynamics in the cerebrospinal fluid: intraindividual concomitant ventricular and lumbar measurements.

OBJECTIVE: The measurement of neuromarker/neuroproteins in the cerebrospinal fluid (CSF) is gaining increased popularity. However, insufficient information is available on the rostrocaudal distribution of neuroproteins in the CSF to guarantee an appropriate interpretation of ventricular versus lumbar concentrations. METHODS: In 10 patients treated with both an external ventricular and a lumbar CSF drain, we collected concomitant CSF samples. We measured CSF concentrations of the glial S100B protein, the neuron-specific enolase (Cobas e411®; Roche Diagnostics), the leptomeningeal ß-trace protein (BN Pro Spec®; Dade Behring/Siemens), and the blood-derived albumin (Immage; Beckman Coulter). Statistical analysis was performed with a paired Wilcoxon signed ranks test. RESULTS: In patients with a free CSF circulation without any recent neurosurgical procedure, S100B and neuron-specific enolase concentrations did not differ between the ventricular and lumbar CSF while ß-trace and albumin levels were significantly higher in the lumbar than in the ventricular CSF (p=0.008 and p=0.005). Following posterior fossa tumor surgery, all proteins accumulate in the lumbar CSF. CONCLUSION: For brain-derived proteins, we could not confirm a rostrocaudal CSF gradient while lepto-meningeal and blood-derived proteins accumulate in the lumbar CSF. We conclude that for the interpretation of protein CSF concentrations, the source of the sample is of crucial importance.

GABA(A) receptor characterization and subunit localization in the human sub-ventricular zone.

It is now well established that the human brain continuously produces new stem cells until well into old age. One of these stem-cell rich areas in the human brain is the sub-ventricular zone (SVZ). The human SVZ is organized in four distinctive layers containing type A, B and C cells. To date, no studies have investigated the distribution of inhibitory neurotransmitters such as γ-aminobutyric acid (GABA) and their respective receptors on the different cell types in the human SVZ. GABA(A) receptors (GABA(A)R) are ubiquitously expressed, inhibitory heteropentameric chloride ion channels comprised of a variety of subunits that are targeted by many prescribed drugs. In this study we present detailed immunohistochemical data on the regional and cellular localization of α1, α2, α3, ß2,3 and γ2 subunits of GABA(A)R in the human SVZ. The results from our double and triple labeling studies demonstrate that the cell types and subunit composition throughout the SVZ is heterogeneous; the thickness of the SVZ and GABA(A)R α2 and γ2 expression is increased especially in the vicinity of large SVZ blood vessels. GABA(A)R γ2 is the most specific to the SVZ and present on various cells that express, either glial fibrillary acidic protein (GFAPδ) or polysialic acid-neural cell adhesion molecule (PSA-NCAM) separately, or together in a respective ratio of 7:6:2. Proliferating (type C) cells in the SVZ express GAD65/67, GFAPδ and GABA(A)R ß2,3 receptor subunits. Within the SVZ the majority of cells have an unexpected nuclear GABA(A)R ß2,3 expression that is inversely proportional to that of PCNA (proliferating cell nuclear antigen marker), which is a very different pattern of expression compared with underlying caudate nucleus cells. Taken together our results provide a detailed description of the chemo-architecture of the adult human SVZ demonstrating the importance of GABA and GABA(A) receptors on the various cell types in the SVZ.

Abnormalities of tau-protein and beta-amyloid in brain ventricle cerebrospinal fluid.

OBJECTIVE: Determination of various biomarkers, such as beta-amyloid, tau-protein, phosphorylated tau-protein in CSF and their sensitivity and specificity in neurodegenerative brain processes, in particular Alzheimer Dementia (AD), has been recently investigated to monitor their abnormalities in the CSF at early stages of diseases before the clinical manifestation. DESIGN AND SETTING: In the pilot group of our patients (10 men / 5 women) who underwent a drainage neurosurgical procedure for diagnosis of hydrocephalus, CSF was obtained from the brain ventricles and the influence of a different compartment of the CSF on the level of biomarkers, tau-protein and beta-amyloid, was investigated. RESULTS: The mean tau-protein level for all 15 patients was 812.0 pg/ml, with median value 363.7 pg/ml; while mean beta-amyloid level for all 15 patients was 526.7 pg/ml, with median value 239.5 pg/ml, respectively. The abnormal tau-protein and beta-amyloid levels were found in the subgroup of patients in whom hydrocephalus was caused by a severe pathological process, such as brain tumor. The beta-amyloid values were significantly lower also in comparison with our previously published results in patients with AD in the CSF obtained by lumbar puncture in the spinal canal. CONCLUSIONS: CSF in the brain ventricles is theoretically more stable and the values in this CSF probably provide more reliable informations for clinical diagnostic procedure than those for the CSF obtained by lumbar puncture in the spinal canal.

Presence of nerve growth factor and TrkA expression in the SVZ of EAE rats: evidence for a possible functional significance.

Nerve growth factor (NGF) is a well-characterized neurotrophic factor that plays a crucial role during development in the growth, differentiation, and maintenance of brain neurons as well as in the reparative response of the adult brain to neuronal damage. Recent studies have shown that acute axonal loss occurs in multiple sclerosis (MS) and its animal model, experimental allergic encephalomyelitis (EAE), and that NGF suppresses clinical symptoms of EAE in nonhuman primates. Aim of the present study was to investigate the role of NGF in the regenerative response of the adult brain to neuronal damage occurring in EAE. Using EAE rats, we have found that exogenous NGF injection and NGF deprivation (NGF autoimmunization) can act on growth and differentiation of brain precursor cells in the subventricular zone (SVZ) of EAE rats. Moreover, NGF administration in brain of EAE rats stimulates the expression of early neuronal markers on proliferating precursor cells of the SVZ. The data obtained demonstrated that NGF and its antibody affect bromodeoxyuridine (BrdU) incorporation and NGF receptor expression by SVZ progenitor cells in the brain of EAE rats.

Clinicopathologic study of 61 patients with ependymoma including MIB-1 immunohistochemistry.

Predicting behavior based on histologic appearance has been problematic in ependymomas. Sixty-one patients with ependymoma (excluding subependymoma and myxopapillary ependymoma) were studied. The patients included 36 men and ranged in age from 1.5 to 74 years (median, 33 years). The most common clinical presentations included headache (n = 19), weakness (n = 18), nausea/vomiting (n = 12), and gait disturbance (n = 10). Location included spinal cord (n = 24), fourth ventricle (n = 21), lateral ventricle (n = 8), and third ventricle (n = 5). Initial surgery included a gross total resection of tumor in 22 patients and subtotal resection or biopsy in the remaining patients. Thirty-five patients were known to have been treated with adjuvant radiation therapy and 13 patients received adjuvant chemotherapy. At last known follow-up, 20 patients were alive with no evidence of tumor (median, 66.5 months), 17 patients were alive with residual tumor (median, 14 months), and 12 patients died of tumor (median, 27.5 months). Two additional patients are alive with tumor status not known, two cases are current, and two patients were lost to follow-up. The additional six patients died either shortly after surgery or of surgical complications. Sixteen of 18 patients had at least one tumor recurrence at median 28.5 months. Fifty-one tumors had a predominantly glial pattern and 10 had a mixed glial-epithelial pattern. Of histologic features examined, patients with tumor recurrence or who died of tumor more frequently had observable mitotic figures, vascular proliferation, necrosis, and foci of increased cellularity. Eight of 18 recurrent tumors were classified as high grade ependymomas (anaplastic/malignant). Of patients who died of tumor, 4 of 12 had histologically high grade tumors versus 5 of 39 of the remaining tumors. MIB-1 immunostaining (marker of cell proliferation) was performed on 50 tumors. MIB-1 labeling indices (% positive tumor cell nuclei) ranged from 0.1 to 34.0 (median, 1.1). A higher percentage of patients with recurrent tumor (6 of 13, 46%) or who died of tumor (3 of 10, 30%) had MIB-1 indices >/= 4.0 versus the remaining patients (8 of 33, 24%). The conclusions are as follows: (1) histologic appearance and MIB-1 indices were not reliably predictive of tumor behavior, probably due in part to tumor heterogeneity; (2) tumors with two or more of the following features: identifiable mitotic figures, hypercellularity, vascular proliferation, and necrosis were more likely to behave in an aggressive manner; and (3) elevated MIB-1 labeling indices (>/=4.0 in this study) were encountered in a higher percentage of fatal and recurrent tumors than in nonfatal or nonrecurrent tumors.

DNA fragmentation and HSP72 gene expression by adenovirus-mediated gene transfer in postischemic gerbil hippocampus and ventricle.

A replication defective adenoviral vector containing the E. coli lacZ gene (AdCMVnLacZ) was directly injected into right hippocampus and lateral ventricle immediately after 5 min of transient global ischemia in gerbils. The relations between the lacZ gene expression and DNA fragmentation or heat shock protein 72 (HSP72) immunoreactivity were examined up to 21 days post ischemia. The lacZ gene was transiently expressed at 1 day in the hippocampus except around the CA1 region, while a large number of the periventricular cells strongly expressed the lacZ gene from 8 h to 7 days. In CA1 layer, terminal deoxynucleotidyl dUTP nick end labeling (TUNEL) positive cells, which were present only adjacent to the needle track at 8 h to 1 day, became more extensive in the whole CA1 layer at 3 to 7 days. TUNEL-positive cells were also detected around the DG at 1 day, around the needle track at 8 h to 3 days, and in the choroid plexus cells at 7 days. HSP72 staining was detected in the subiculum at 1 to 3 days, the dentate granule cells at 8 h to 1 day, and in the CA3 or CA4 pyramidal cells at 1 to 3 days. Some lacZ expressing cells were double-positive with HSP72 in DG, while the majority of those were distinguished from the TUNEL-positive cells. Pyramidal neurons were almost completely lost in the CA1 sector at 7 days after the ischemia. The present study demonstrates the successful LacZ gene transfer into the hippocampus and ventricle of postischemic gerbil brain except in the vulnerable CA1 layer by adenoviral vector injection. However, adenovirus-mediated gene transfer may induce indirect apoptotic cell death in the DG and ventricle, in addition to direct traumatic injury around the needle track.

Estrogen receptor and progesterone receptor-immunoreactive cells are not co-localized with gonadotropin-releasing hormone in the brain of the female mink (Mustela vison).

The distribution of gonadal steroid (estrogen, progesterone) receptors in the brain of the adult female mink was mapped by immunocytochemistry. Using a monoclonal rat antibody raised against human estrogen receptor (ER), the most dense collections of ER-immunoreactive (IR) cells were found in the preoptic/anterior hypothalamic area, the mediobasal hypothalamus (arcuate and ventromedial nuclei), and the limbic nuclei (amygdala, bed nucleus of the stria terminalis, lateral septum). Immunoreactivity was mainly observed in the cell nucleus and a marked heterogeneity of staining appeared from one region to another. A monoclonal mouse antibody raised against rabbit uterine progesterone receptor (PR) was used to identify the PR-IR cells in the preoptic/anterior hypothalamic area and the mediobasal hypothalamus (arcuate and ventromedial nuclei). This study also focused on the relationship between cells containing sex-steroid receptors and gonadotropin-releasing hormone (GnRH) neurons on the same sections of the mink brain using a sequential double-staining immunocytochemistry procedure. Although preoptic and hypothalamic GnRH neurons were frequently in close proximity to perikarya containing ER or PR, they did not themselves possess receptor immunoreactivity. The present study provides neuroanatomical evidence that GnRH cells are not the major direct targets for gonadal steroids and confirms for the first time in mustelids the results previously obtained in other mammalian species.

Elevated 4-hydroxynonenal in ventricular fluid in Alzheimer's disease.

4-Hydroxynonenal (4-HNE), an aldehyde by-product of the peroxidation of fatty acids, has been shown to have toxic properties for neurons in culture. In light of increasing evidence that oxidative stress contributes to the neurodegenerative process in Alzheimer's disease (AD), we quantified levels of free and protein-bound 4-HNE in the ventricular fluid from 19 AD subjects and 13 control subjects by high-pressure liquid chromatography and dot-blot immunoassay. Free 4-HNE levels were found to be significantly elevated in the ventricular fluid of AD subjects compared with control subjects (p = 0.0096). These results demonstrate increased lipid peroxidation in AD brain and suggest a role for 4-HNE in the neurodegenerative process.

Does a short loop feedback mechanism for the control of luteinizing hormone secretion exist in the ewe?

It is not known whether a short loop feedback mechanism for the regulation of LH exists in sheep. This study on ovariectomized ewes investigated whether a bolus injection (10, 1, and 0.1 microg LH or 1 microg BSA; n 4) or a 3-h continuous infusion of exogenous LH (100 or 1 ng/min; n = 7) into the third ventricle through a permanent indwelling cannula could influence the activity of the GnRH pulse generator, as determined by measurement of endogenous LH secretion. To assess the potential for involvement in a LH short loop feedback system and to estimate the level of LH in the hypothalamic milieu, the concentrations of LH in the peripheral circulation, portal circulation, and third ventricle were measured during an estradiol-induced preovulatory LH surge (n = 4). Neither the bolus nor continuous administration of LH into the third ventricle had any effect on the mean interpulse interval, nadir, pulse amplitude, or circulating level of systemic LH. Furthermore, despite portal LH concentrations being more than 20-fold higher than jugular LH concentrations, LH levels in third ventricular cerebrospinal fluid remained barely detectable and did not reflect dynamic secretory events in the peripheral or hypothalamo-hypophyseal portal blood. These data demonstrate that in ewes, little pituitary LH reaches the third ventricle, and the small amount that does is unable to affect peripheral gonadotropin release. Our study suggests, therefore, that a short loop feedback system for LH does not exist in the ewe.

Correlation between ANP concentrations in atria, plasma and cerebral structures and sodium chloride preference in Wistar rats

We determined whether ANP (atrial natriuretic peptide) concentrations, measured by radioimmunoassay, in the ANPergic cerebral regions involved in regulation of sodium intake and excretion and pituitary gland correlated with differences in sodium preference among 40 Wistar male rats (l80-220 g). Sodium preference was measured as mean spontaneous ingestion of 1.5 per cent NaCl solution during a test period of 12 days. The relevant tissues included the olfactory bulb (OB), the posterior and anterior lobes of the pituitary gland (PP and AP, respectively), the median eminence (ME), the medial basal hypothalamus (MBH), and the region anteroventral to the third ventricle (AV3V). We also measured ANP contens in the right (RA) and left atrium (LA) and plasma. The concentrations of ANP in the OB and the AP were correlated with sodium ingestion during the preceding 24 h, since an increase of ANP in these structures was associated with a reduced ingestion and vice-versa (OB: r = -0.3649, P<0.05; AP: r = -0.3291, P<0.05). Moreover, the AP exhibited correlation between ANP concentration and mean NaCl intake (r = -0.4165, P<0.05), but this was not the case for the OB (r = 0.2422. This suggests that differences in sodium preference among individu male rats can be related to variations of AP ANP level. Earlier studies indicated that the OB is involved in the control of NaCl ingestion. Our data suggest that the OB ANP level may play a role mainly in day-today variations of sodium ingestion in the individual rat.

bcl-2 protein is increased in the brain from parkinsonian patients.

The proto-oncogene bcl-2 is involved in the regulation of cell death and may be able to block apoptosis in neurons through reduced generation of reactive oxygen species (ROS). The bcl-2 product was measured for the first time in brain (caudate nucleus, putamen and cerebral cortex), ventricular cerebrospinal fluid (VCSF), and lumber CSF (LCSF) from control and parkinsonian patients by highly sensitive two-site sandwich enzyme-linked immunosorbent assay (ELISA). The concentrations of bcl-2 in the nigrostriatal dopaminergic regions were significantly higher in parkinsonian patients than those in controls, whereas this product in cerebral cortex showed no significant difference between parkinsonian and control subjects. Neither VCSF nor LCSF from control or parkinsonian subjects contained the bcl-2 product in the detectable amount (< 5 U/ml). Since oxidative stress may be involved in neurogenerative disorders, accumulation of bcl-2 may reflect a mechanism for counterbalancing ROS-mediated damage, or it might represent the impairment of bcl-2-dependent protection from ROS in parkinsonian brain.

Cortical lesions induce an increase in cell number and PSA-NCAM expression in the subventricular zone of adult rats.

The subventricular zone (SVZ) bordering the lateral ventricle is one of the few regions of adult brain that contains dividing cells. These cells can differentiate into neurons in vivo after migration into the olfactory bulb and in vitro in the presence of appropriate growth factors. Little is known, however, about the fate of these cells in vivo after brain injury in adults. We examined cell number and expression of differentiation markers in the SVZ of adult rats after cortical lesions. Aspiration lesions of the sensorimotor cortex in adult rats induced a transient doubling of the number of cells in the SVZ at the level of the striatum without consistent increases in bromodeoxyuridine-labeled cells. Immunoreactivity to the polysialylated neural cell adhesion molecule, expressed by the majority of cells of the SVZ during development, increased dramatically after lesion. In contrast, immunolabeling for molecules found in mature neurons and glia did not increase in the SVZ after lesion, and immunoreactivity for growth factors that induce differentiation of SVZ cells in vitro decreased or remained undetectable, suggesting that lack of appropriate growth factor expression may contribute to the lack of differentiation of the newly accumulated cells in vivo. The data reveal that cells of the SVZ are capable of plasticity in the adult rat after brain injury in vivo and that the newly accumulated cells retain characteristics seen during development.

Immunoreactivity for apolipoprotein A-IV in tanycytes and astrocytes of rat brain.

Immunoperoxidase and immunofluorescence procedures were used to visualize polyclonal antiserum binding to apolipoprotein (apo) A-IV in rat brain. With both methods, tanycytes and astrocytes were labeled throughout both white and gray matter. Within the cells, the labeling was granular and it was confined to the perinuclear zone and proximal regions of the processes. The labeling was abolished by absorption of the primary antiserum with purified apo A-IV but not by absorption with apo E. These results suggest either that apo A-IV is synthesized by astrocytes, or that apolipoprotein that is synthesized in the small intestine or liver is selectively taken up and stored by the astrocytes.

Sodium depletion induces Fos immunoreactivity in circumventricular organs of the lamina terminalis.

Acute sodium depletion by peritoneal dialysis (PD) induces c-fos expression in the subfornical organ (SFO) and organum vasculosum laminae terminalis (OVLT), in conscious rats. Fos immunoreactive (Fos-ir) neurons detected by immunohistochemistry first appeared in these nuclei 60 min after PD, increased gradually in the next 4 h and remained high for 27 h following PD. Fos-ir cells were distributed throughout the body of SFO, being the core of the posterior sections preferentially activated, whereas Fos-ir neurons occurred around the periphery of OVLT (annular disposition). When rats were allowed to drink sodium salt (1.8% NaCl) 24 h after PD, there was a marked reversion of the c-fos expression in the OVLT and a comparatively smaller effect in the SFO. Intracerebroventricular infusion of hypertonic CSF (170 mM NaCl) from 30 min before and during 4 h after PD, significantly inhibited the c-fos expression in both nuclei. These results demonstrate that an acute body sodium deficit induces c-fos activity in SFO and OVLT neurons, indicating the special role of these structures in sodium balance regulation. They also show that the sodium-depletion-induced production of Fos in neurons of the lamina terminalis can be modulated by central or systemic reposition of sodium.

Central neurocytoma. A clinicopathological, immunohistochemical and ultrastructural study of 7 cases.

Characterised by distinctive clinicopathological features, the central neurocytoma (CN) is an uncommon and possibly under-recognised primary cerebral neuronal neoplasm. We present clinical and pathological details of seven patients with CN. Histological examination revealed a greater diversity of morphological appearances than is typically described in CN. No anaplastic features were identified. Cellular areas resembling both oligodendroglioma and ependymoma were present in all cases, but each tumour also contained stroma rich areas with hyalinised or aneurysmal vessels. Synaptophysin was expressed by all tumours and probably represents the immunohistochemical marker of choice for identifying CN. Distinguishing ultrastructural features included rounded cell bodies separated by numerous cell processes containing microtubules, pleomorphic neurosecretory granules and occasional synapses. Ki-67 immunostaining revealed a low cell proliferation index in each case. The distinction of CN from other pathological mimics can be reliably made using this multiparametric approach to diagnosis. The generally benign behaviour of CN is confirmed, though there was one patient death in the follow-up period of 10-122 months. Aggressive behaviour in this case was not associated with anaplastic histological features.

Electron-microscopic investigations of vasoactive intestinal peptide (VIP)-like immunoreactive terminal formations in the lateral septum of the pigeon.

Vasoactive intestinal peptide (VIP)-like immunoreactive terminal fields were examined in the lateral septum of the pigeon by means of immunocytochemistry. According to light-microscopic observations, these projections originated from VIP-like immunoreactive cerebrospinal fluid (CSF)-contacting neurons, which are located in the ependymal layer of the lateral septum and form a part of the lateral septal organ. The processes of these cells gave rise to dense terminal-like structures in the lateral septum. Pre-embedding immuno-electron microscopy revealed that VIP-like immunoreactive axon terminals had synaptoid contacts with perikarya of small VIP-immunonegative neurons of the lateral septum, which were characterized by an invaginated nucleus, numerous mitochondria, a well-developed Golgi apparatus, endoplasmic reticulum and a small number of dense-core vesicles (about 100 nm in diameter). VIP-like immunoreactive axons were also seen in contact with immunonegative dendrites in the lateral septum. In both axosomatic and axodendritic connections, VIP-like immunoreactive presynaptic terminals contained large dense-core vesicles, clusters of small vesicles and mitochondria. These findings suggest that VIP-immunoreactive neurons of the lateral septal organ project to small, presumably peptidergic nerve cells of the lateral septum and that the VIP-like neuropeptide serves as a neuromodulator (-transmitter) in this area.

Colloid cyst of the third ventricle. A comparative immunohistochemical study of neuraxis cysts and choroid plexus epithelium.

In an effort to shed light upon the nature of the colloid cyst, the immunohistochemical properties of 21 examples of this lesion were compared with those of other neuraxial cysts and choroid plexus epithelium. The neuraxial cysts included the following: eight Rathke's cleft cysts, 25 pituitaries containing follicular cysts of the pars intermedia, and four enterogenous cysts. Fifteen examples of normal choroid plexus and 12 choroid plexus papillomas were studied as well. These lesions were examined for localization of the following antigens: cytokeratins, epithelial membrane antigen, secretory component, carcinoembryonic antigen, prealbumin, vimentin, glial fibrillary acidic protein (GFAP), S-100 protein, neuron-specific enolase, 68-kD neurofilament protein, chromogranin, serotonin, and lysozyme, and with Leu-7 monoclonal antibodies. Five colloid cysts were immunostained with monoclonal antibodies that were specific for Clara-cell antigens and surfactant, respectively. Sugar moieties were localized using Ulex europaeus I, and Ricinus communis agglutinin I lectins. All Rathke's cleft cysts and follicular cysts of the pars intermedia as well as three selected colloid cysts were examined for pituitary hormones. The epithelial cells of colloid and enterogenous cysts, as well as those lining follicular and Rathke's cleft cyst, showed uniformly strong reactivity for cytokeratins, epithelial membrane antigen, secretory component, and vimentin, and bound Ulex europaeus lectin. Occasional cells in colloid cysts were positive for Clara cell-specific antigens. Reaction for carcinoembryonic antigen was present on the apical surface of scattered cells of colloid, follicular, and Rathke's cleft cysts. Many cells of follicles in the pars intermedia as well as individual cells of five Rathke's cleft cysts were also immunoreactive for chromogranin, S-100 protein, GFAP, and pituitary hormones. Colloid and enterogenous cysts were negative for prealbumin, S-100 protein, GFAP, and neuron-specific enolase; in all but a few instances, they failed to bind Ricinus communis agglutinin. In contrast, normal choroid plexus and choroid plexus papillomas were positive for prealbumin, S-100 protein, neuron-specific enolase, cytokeratin, vimentin, and Ricinus communis agglutinin receptors; they lacked Ulex europaeus lectin, 56/66-kD cytokeratins, and epithelial membrane antigen. Unlike normal choroid plexus, choroid plexus papillomas were often GFAP-positive. All tissues studied were nonreactive for lysosome, serotonin, and neurofilament, and with Leu-7 antibodies. This study indicates that the immunophenotype of epithelium lining colloid cysts is similar to that of other cysts showing endodermal or ectodermal differentiation and to respiratory tract mucosa. Epithelium of colloid cysts is immunohistochemically different from that of normal or neoplastic choroid plexus. These findings indicate an endodermal rather than neuroepithelial nature for colloid cysts.

Photoperiodic regulation of substance P immunoreactivity in the mating behavior pathway of the male golden hamster.

Mating behavior in the male golden hamster is regulated by both gonadal steroids and photoperiod. Gonadal steroids may regulate mating behavior by actions on the medial nucleus of the amygdala, bed nucleus of the stria terminalis, and medial preoptic area. Neurons in these areas actively accumulate gonadal steroids and lesions of these nuclei disrupt mating behavior in male hamsters. Photoperiodic regulation of mating behavior is regulated, at least in part, by decreased responsiveness to gonadal steroids. Therefore, we sought to determine if the changes induced by changes in gonadal steroids would mimic those induced by changes in photoperiod. The number of substance P-containing neurons in these areas decrease following castration and are restored with testosterone treatment suggesting that this peptide may mediate steroidal regulation of male mating behavior. To determine the effect of photoperiod on substance P, peptide containing neurons were counted in (1) enucleates (n = 6), (2) enucleated castrates treated with testosterone (n = 6), (3) castrates treated with testosterone (n = 4), and (4) intact controls (n = 6). Bilateral enucleation caused a decrease in the number of substance P neurons in the medial nucleus, bed nucleus of the stria terminalis, and medial preoptic area (P less than 0.05). Testosterone treatment prevented this decrease (P less than 0.05). Thus, a decrease in daylength causes a decrease in substance P in the medial nucleus of the amygdala, the medial bed nucleus of the stria terminalis and the medial preoptic area that is mediated by changes in testosterone levels.

Colloid cysts of the third ventricle: immunohistochemical evidence for nonneuroepithelial differentiation.

The histogenesis of colloid cysts (CCs) of the third ventricle has been a subject of controversy. We examined, using immunohistochemical techniques, four CCs for the presence of cytokeratins (CKs), glutathione S-transferase isoenzymes (GST-pi, GST-mu), and glial fibrillary acidic protein. Antibodies to both low molecular weight CKs (anti-CK8) and to a mixture of CKs (AE1/AE3) were used. For comparison, normal fetal and adult choroid plexus, ependyma, and nasal mucosa were also examined. The epithelium lining all four CCs showed positive immunostaining for the CKs and GST-pi but not for GST-mu or glial fibrillary acidic protein. Fetal and adult nasal mucosa showed a pattern of immunohistochemical staining almost identical to that of CCs. In contrast, fetal and adult choroid plexus tissue showed positive immunostaining for GST-pi and low molecular weight CKs but not for the CK mixture (AE1/AE3). Fetal and adult ependyma were negative for both CKs and GST-pi. These results suggest that CCs differentiate along nonneural lines distinct from the neuroepithelial differentiation of the choroid plexus and ependyma.