Heterogeneous distribution of polyamines in temporal lobe epilepsy

Polyamine contents were determined in human temporal lobe epilepsy. In the seven patients studied, stereoelectroencephalography (SEEG) located the epileptogenic focus in Ammon's horn and neuropathological findings were limited to hippocampal gliosis and sclerosis. Each polyamine exhibited a specific regional distribution. The most important variations were observed for spermidine and spermine while putrescine levels varied less. The regional variation was predominant in middle > posterior > anterior parts of the temporal lobe. Spermine contents and the spermidine/spermine (SPD/SPM) index varied especially in the middle and posterior parts of the hippocampus. Metabolic SPD/SPM index and spermidine levels were found to be drastically increased in almost all limbic parts when compared to neocortical regions. The opposite was observed for spermine. The heterogeneous distribution of polyamines was compared to abnormal electrical activities recorded by SEEG: SPD/SPM index and spermidine levels were sharply increased in seizure onset areas and high levels of spermine were detected in temporal cortex propagation areas. The presently reported heterogeneity of polyamine contents might contribute to modulate differentially the local control of excitability in human temporal epilepsy.

Effects of dopamine on the in vivo binding of dopamine D2 receptor radioligands in rat striatum

The effects of moderate changes in extracellular dopamine concentrations on the in vivo binding of specific dopaminergic D2 radioligands with different affinities and kinetics were investigated in rats. Either [125I]NCQ298 (Kd = 19 pM), or [25I]iodolisuride (Kd = 0.27 nM) or [3H]raclopride (Kd = 1.5 nM) were administered intravenously (IV) to animals 1 h after the intraperitoneal (IP) injection of either alpha-methyl-p-tyrosine (AMPT) (250 mg/kg) or nomifensine (15 mg/kg), or saline. The kinetics of radioactivity concentration in the striatum, cerebellum, and plasma were measured for up to 4 h after [125I]NCQ298 or [125I]iodolisuride injection and up to 1.5 h after [3H]raclopride injection. For each tracer, the striatum-to-cerebellum radioactivity concentration ratios (S/C) and the binding potential (BP), calculated as the association to dissociation binding rate constant ratios (k3/k4), were assessed and related to the changes in extracellular dopamine concentration induced by drug treatments. Results show that S/C and BP of [3H]raclopride were significantly diminished by pretreatment with nomifensine, a drug that increases extracellular dopamine concentration. Nomifensine pretreatment induced no changes in the in vivo binding indexes of the high affinity [125I]NCQ298 and a slight but not significant decrease of the binding indexes of 125I]iodolisuride. Treatment with AMPT, which induced a 40% reduction in dopamine concentration, did not change [125I]NCQ298 binding indexes but slightly increased those of [3H]raclopride and [125I]iodolisuride. In conclusion, the change of dopamine concentration induces modification of radiotracer kinetics. Thus, the combined use of tracers with high and low affinities could allow us to obtain information both on receptor density and neurotransmitter release in vivo. However, as indicated by the [3H]raclopride study with AMPT, small changes in the concentration of intrasynaptic dopamine cannot be easily detected.

Glutamate induces phosphorylation of Elk-1 and CREB, along with c-fos activation, via an extracellular signal-regulated kinase-dependent pathway in brain slices

In cell culture systems, the TCF Elk-1 represents a convergence point for extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) subclasses of mitogen-activated protein kinase (MAPK) cascades. Its phosphorylation strongly potentiates its ability to activate transcription of the c-fos promoter through a ternary complex assembled on the c-fos serum response element. In rat brain postmitotic neurons, Elk-1 is strongly expressed (V. Sgambato, P. Vanhoutte, C. Pagès, M. Rogard, R. A. Hipskind, M. J. Besson, and J. Caboche, J. Neurosci. 18:214-226, 1998). However, its physiological role in these postmitotic neurons remains to be established. To investigate biochemically the signaling pathways targeting Elk-1 and c-fos in mature neurons, we used a semi-in vivo system composed of brain slices stimulated with the excitatory neurotransmitter glutamate. Glutamate treatment leads to a robust, progressive activation of the ERK and JNK/SAPK MAPK cascades. This corresponds kinetically to a significant increase in Ser383-phosphorylated Elk-1 and the appearance of c-fos mRNA. Glutamate also causes increased levels of Ser133-phosphorylated cyclic AMP-responsive element-binding protein (CREB) but only transiently relative to Elk-1 and c-fos. ERK and Elk-1 phosphorylation are blocked by the MAPK kinase inhibitor PD98059, indicating the primary role of the ERK cascade in mediating glutamate signaling to Elk-1 in the rat striatum in vivo. Glutamate-mediated CREB phosphorylation is also inhibited by PD98059 treatment. Interestingly, KN62, which interferes with calcium-calmodulin kinase (CaM-K) activity, leads to a reduction of glutamate-induced ERK activation and of CREB phosphorylation. These data indicate that ERK functions as a common component in two signaling pathways (ERK/Elk-1 and ERK/?/CREB) converging on the c-fos promoter in postmitotic neuronal cells and that CaM-Ks act as positive regulators of these pathways.

Large conductance channel in plasma membranes of astrocytic cells is functionally related to mitochondrial VDAC-channels

Large conductance anion channels with similar electrophysiological characteristics were found in plasma membranes and in outer mitochondrial membranes of various cell types. Although their large conductance and their peculiar voltage dependence point to a close relation, it was questioned whether they belong to the same family. We therefore compared some biochemical features of a plasmalemmal channel with those known from the mitochondrial channel. Current events were recorded from excised patches of plasma membranes of a rat astrocytic cell line (RGCN). The underlying channels exhibited a conductance of 401 +/- 50 pS. Open probability was highest between +/- 10 mV and gradually approached zero beyond +/- 25 mV. Activity as induced by voltage ramps between +/- 40 mV appeared after a delay of up to several min. The delay could be reduced by bathing either side of the patch in an acidic Ringer solution (pH 6.2). 1 mM Al3+ increased the open time at potentials more positive than 20 mV. 10 mM dextran sulfate (MW 8000) caused reversible flickering, increasing the closed probability. 4,4'-diisothiocyanatostilbene-2,2' disulfonic acid (DIDS) also caused a reversible flickering into the closed state, reducing the apparent single channel amplitude by up to 70% at 0.5 mM DIDS. Application of 5 mM ATP resulted in reversible blockade; ATP was more effective from the outside than from the inside (blocking activity 65% vs. 16% of the patches). We conclude that the large conductance anion channel from astrocytic cells displays electrophysiological and pharmacological characteristics that resemble those of VDAC (Voltage Dependent Anion Channel) from the outer mitochondrial membrane.

[Long-term outcome of 72 patients surgically treated for stage II non-small cell bronchial cancer, between 1982 and 1989]

We report a 72 patients trial, who had surgical treatments for non small cell lung cancer, stage II (T1N1, T2N1). In our retrospective study, the overall 5-years survival is 44%, with a 24-month median survival. 45% of the patients have recurrence mainly due to distant metastasis. State II appears to be an heterogeneous group. As shown in other studies, the presence of hilar nodes (N1H) seems to be linked with a pejorative outcome. In our series, the survival associated with Lobar N1 (N1L) disease is the same as the survival of Hilar N1 disease, but the initial sites of recurrence differ. The interest of a postchirurgical treatment is controversial. The postoperative radiotherapy reduces the local recurrence without increasing the survival. The chemotherapy treatment is debatable and several studies are under way. We reviewed the different causes of death. The appearance of second cancer in the cured patients is very frequent.

Human immunodeficiency virus type 1 and its coat protein gp120 induce apoptosis and activate JNK and ERK mitogen-activated protein kinases in human neurons

Detection of apoptotic neurons and microglial cells in the brains of human immunodeficiency virus type 1 (HIV-1)-infected patients has suggested that programmed cell death may be implicated in the physiopathology of HIV-1 encephalopathy. To analyze in vitro the intracellular signals induced by HIV-1 in human neurons and the associated neuronal death, we tested cultured human central nervous system (CNS) cells for apoptosis induced by HIV-1 and gp120 and for signaling pathways activated by gp120. HIV-1 and gp120 induced apoptosis of neurons and microglial cells but not of astrocytes or transformed microglial cells. Gp120 activated c-Jun N-terminal kinase (JNK) and p42 extracellular-regulated kinase (ERK) in primary CNS cells, with an early peak of activation at 2 to 5 minutes that was not present when pure microglial or astrocyte cultures were tested, followed by a late and sustained activation (10 and 60 minutes) in primary and enriched glial cell cultures as well as in transformed microglial cells. This demonstrates that gp120 could be an effector of HIV-1-induced apoptosis in the CNS and act directly on neuronal and glial cells.

Clear cell tumor of the lung: an immunohistochemical and ultrastructural study supporting a pericytic differentiation

Clear cell tumor ("sugar tumor") of the lung is a rare benign lesion with unclear histogenesis. It is composed of large cells with a clear cytoplasm rich in glycogen, blended with an abundant network of sinusoid-type vessels. We report two cases of sugar tumor, one of these lacking clearly demonstrable glycogen storage. In both, the tumor cells lacked keratin expression and were positive for vimentin and HMB 45, an antibody recognizing perivascular or myoid cell proliferation such as lymphangioleiomyomatosis and angiomyolipoma. The tumor cells were also immunoreactive for an endothelial cell marker, CD 34, but negative for Factor VIII or smooth muscle actin. Intercellular deposition of basal-like material was immunostained with Type IV collagen. At ultrastructural examination of one of these cases, tumor cells showing features of pericytes or poorly differentiated perivascular leiomyocytes encased in basement material were observed in close association with endothelial cells; their cytoplasm contained numerous membrane-bound glycogen and pinocytic vesicles. We conclude that on the basis of immunohistochemical and ultrastructural phenotype, sugar tumor presents pericytic features and that glycogen storage is not a constant feature of these benign tumors.

[Endovascular closure of a foramen ovale after a right pneumonectomy]

We report the case of a patient, 62-year-old, with a non small cell lung cancer treated by right pneumonectomy followed by chemo and radiotherapy. After surgery appeared a refractory hypoxemia increasing with supine position. Cardiac catheterism showed a right left shunt by reopening of the "foramen ovale". We have performed foramen's occlusion by endovascular method with prothetic material with good result until the death, 14 months later, by neoplasic evolution.

RU 41740 (Biostim) stimulates the production of granulocyte macrophage colony-stimulating factor and interleukin-8 by human bronchial epithelial cells in vitro

1. In this study, we observed the effects of RU 41740 (Biostim) on the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-8 (IL-8) in human bronchial epithelial cells in vitro. 2. Cytokine production was assessed by enzyme-linked immunosorbent assay. 3. We report that epithelial cells spontaneously released both cytokines and that RU 41740 induced a significant increase in production of IL-8 and GM-CSF. 4. This is the first observation of a stimulatory effect of an immunostimulating compound used in humans on cytokine production by epithelial cells.

[Malignant mesothelioma of the pleura following radiotherapy of Hodgkin disease]

Second neoplasms following chemotherapy and radiotherapy for Hodgkin's disease have been extensively described, including acute myeloblastic leukemia, non Hodgkin's lymphomas and various solid tumors. We report malignant pleural mesothelioma occurring 17 years after mantle radiotherapy and MOPP chemotherapy for Hodgkin's disease. According to Cahan's criteria, this mesothelioma may be considered as treatment-related. Fourteen similar cases have been previously published. Post-radiation mesothelioma might be characterised by limited stage at diagnosis and might be surgically removed at presentation.

Antihistamines and production of granulocyte-macrophage colony-stimulating factor and interleukin-8 by human bronchial epithelial cells in vitro: evaluation of the effects of loratadine and cetirizine

1. In this study, we compared the effects of two antihistamine drugs on the production of granulocyte-macrophage colony-stimulating factor and interleukin-8 by human bronchial epithelial cells in vitro. 2. Cytokine production was assessed by the use of an enzyme-linked immunosorbent assay. 3. Epithelial cells spontaneously released both cytokines and tumor necrosis factor alone induced a significant increase in this production but loratadine and cetirizine had no effect at the various concentrations studied. 4. The antihistamines have no effect and this suggests that histamine plays no role in cytokine production under these conditions.

[Spontaneous hydro-pneumothorax disclosing malignant mesothelioma. Apropos of 2 cases]

We report the cases of two males who presented with spontaneous complete unilateral pneumothorax with ipisilateral liquid effusion. Neither had a history of previous respiratory disease. In both cases chest tube drainage resulted in recurrence of pneumothorax with chronic illness requiring surgical exploration. The surgery revealed a malignant pleural mesothelioma by histological examination. Thus, spontaneous pneumothorax, particularly with abondant effusion can be a revealing symptom of malignant pleural mesothelioma.

Direct in vivo comparison of two mechanisms releasing dopamine in the rat striatum

A push-pull cannula supplied with artificial CSF was implanted in the striatum of anaesthetized rats, and the basal extracellular DA and DOPAC was assayed in the superfusates using HPLC and electrochemical detection. Simultaneously, a carbon fibre electrode was implanted in close proximity of the cannula and the evoked DA release was detected by differential pulse amperometry during stimulation of the DA axons. Local treatments with cadmium (100 microM) blocked the evoked DA release (-90%), but substantially increased the basal extracellular DA (+125%). The effects of glutamate agonists NMDA (1 mM) and kainate (0.1 mM), known to increase basal extracellular DA were confirmed (+150% and +60% respectively). It was, however, simultaneously observed that the evoked DA release was inhibited (-80% and -50%, respectively). Amphetamine (1 microM) released DA (+150%) and produced also an increase (+100%) of the evoked DA release. These results, apparently conflicting, show that the two mechanisms releasing dopamine (firing-dependent and not) can be directly and simultaneously observed. These two releasing processes appear to be not strictly antagonist. They are also differently and independently modulated by calcium and by local influences such those conveyed by glutamate.

Acute stimulatory effect of estradiol on striatal dopamine synthesis

The acute effect of physiological doses of estradiol (E2) on the dopaminergic activity in the striatum was studied. In a first series of experiments, ovariectomized rats were injected with 17 alpha or 17 beta E2 (125, 250, or 500 ng/kg of body weight, s.c.), and in situ tyrosine hydroxylase (TH) activity (determined by DOPA accumulation in the striatum after intraperitoneal administration of NSD 1015) was quantified. A dose-dependent increase in striatal TH activity was observed within minutes after 17 beta (but not 17 alpha) E2 treatment. To examine whether E2 acts directly on the striatum, in a second series of experiments, anesthetized rats were implanted in the striatum with a push-pull cannula supplied with an artificial CSF containing [3H]tyrosine. The extracellular concentrations of total and tritiated dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were measured at 20-min intervals. Addition of 10(-9) M 17 beta (but not 17 alpha) E2 to the superfusing fluid immediately evoked an approximately 50% increase in [3H]DA and [3H]DOPAC extracellular concentrations, but total DA and DOPAC concentrations remained constant. This selective increase in the newly synthesized DA and DOPAC release suggested that E2 affects DA synthesis rather than DA release. Finally, to determine whether this rapid E2-induced stimulation of DA synthesis was a consequence of an increase in TH level of phosphorylation, the enzyme constant of inhibition by DA (Ki(DA)) was calculated. Incubation of striatal slices in the presence of 10(-9) M 17 beta (but not 17 alpha) E2 indeed evoked an approximate twofold increase in the Ki(DA) of one form of the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Granulocyte-macrophage colony stimulating factors (GM-CSF) and interleukin 8 (IL-8) production by human bronchial epithelial cells (HBEC) in asthmatics and controls. Lack of in vitro effect of salbutamol compared to sodium nedocromil

The bronchial epithelium produces cytokines that could contribute to inflammatory events in airways. In this study we determined the basal and TNFalpha stimulated productions of GM-CSF and IL-8 by human bronchial epithelial cells (HBEC) collected from 12 control and six asthmatic patients. Spontaneous and TNFalpha-induced GM-CSF or IL-8 released levels increased significantly with time. Epithelial cells from asthmatic patients spontaneously released high levels of GM-CSF (24 h). TNFalpha potentiated GM-CSF and IL-8 release in control subjects and only the IL-8 production in asthmatics. Nedocromil sodium, an antiinflammatory drug, and salbutamol, a beta2-agonist, are commonly used in asthma. They were evaluated on the spontaneous and TNF-induced expression of GM-CSF and IL-8 in cultured bronchial epithelial cells. Nedocromil sodium, at the concentration of 10(-6) M, reduced the TNF-induced increase in GM-CSF but not the IL-8 release. Salbutamol, at the concentration of 10(-6) or 10(-5) M, did not affect the constitutive or stimulated production of both cytokines.

TH mRNA over-expression in rats with chronic excitotoxic striatal lesions

Twenty weeks after ibotenic acid lesions of the striatum, the amount of tyrosine hydroxylase (TH) in this structure was markedly increased. This was accompanied by a 3-fold increase in TH mRNA levels in the ipsilateral subtantia nigra (SN). Striatal levels of dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) were markedly reduced. In the nucleus accumbens, spared by the lesion, DA neurotransmission was also altered, as evidenced by a reduction of DA and DOPAC, but no increase in TH could be detected. TH mRNA levels were moderately enhanced in the ventral tegmental area (VTA). Thus, lesioning in the striatum induces TH gene activation in both SN and VTA neurones, not strictly related to DA function at the terminal level.

Regulation of tyrosine hydroxylase gene expression in mesencephalic dopamine neurons: effect of imipramine treatment

The effects of a chronic imipramine treatment on the mesoamygdaloid pathway of rats were examined. Using semiquantitative immunocytochemical techniques, it was observed that the level of TH mRNA was decreased in the ventral tegmental area (VTA). In contrast, the TH protein was increased in both the VTA and amygdala. The TH activity was decreased in the amygdala when assessed under normal conditions but increased after a preincubation to phosphorylate the enzyme, suggesting a lowering of the protein-specific activity in the terminals. These results show that TH protein turnover in the mesoamygdaloid neurons can be reduced by chronic imipramine treatments, thereby producing an accumulation of inactive TH protein in the neurons while also decreasing TH gene activity in the cell bodies.

Antibiotics and production of granulocyte-macrophage colony-stimulating factor by human bronchial epithelial cells in vitro. A comparison of cefodizime and ceftriaxone

Cultured human bronchial epithelial cells (HBEC) produce both granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 8 (IL-8). The influence of cefodizime (CAS 69739-16-8), a new broad spectrum cephalosporin with immunostimulatory effects, and ceftriaxone on the production of GM-CSF and IL-8 in HBEC primary cultures was investigated. HBEC were isolated from biopsy specimens obtained during fibreoptic bronchoscopy in 12 patients (most frequent diagnosis: chronic bronchitis). Confluent monolayers of HBEC cultured on collagen were incubated for 24 h in a medium without study drugs (spontaneous production) or containing cefodizime or ceftriaxone at the clinically relevant concentrations of 1, 10 and 100 mg/l, with or without tumor necrosis factor alpha (TNF alpha, 100 U/ml). GM-CSF and IL-8 were measured in supernatant by ELISA technique. TNF alpha alone led to a significant (p < 0.005) increase in both GM-CSF and IL-8 production. Cefodizime induced a significant (p < 0.05), dose-dependent increase in GM-CSF release. No additive effect of cefodizime with TNF alpha was observed. Cefodizime did not affect IL-8 production and ceftriaxone had no influence on cytokine production. This is the first report of a stimulatory effect of a beta-lactam antibiotic on cytokine production by epithelial cells. GM-CSF production by epithelial cells is an important immunological step for neutrophil and monocyte recruitment and cell priming during lung defence. Previous studies with cefodizime in immunodepressed subjects have shown activation of phagocytosis and phagocytosis-related functions in non-lung phagocytes. An indirect mechanism of action, similar to that indicated by our results, may have been responsible for these stimulatory effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional chemotherapy (with mitomycin C) and intra-operative hyperthermia for digestive cancers with peritoneal carcinomatosis

Intraperitoneal chemo-hyperthermia with mitomycin C was used to treat 28 patients with far advanced digestive adenocarcinoma and histologically confirmed peritoneal carcinomatosis. Surgical resection of the primary tumor was possible in 17 cases. After closure of the abdominal wall, intraperitoneal chemo-hyperthermia was performed for 90 to 120 minutes under general anesthesia and 32 degrees C hypothermia, through 3 intraperitoneal drains forming a closed circuit, using 10 mg/l of mitomycin C in 6 liters of peritoneal dialysate heated to an inflow temperature of 46-49 degrees C. No mortality occurred, and there were 2 post-operative complications, with transitory biological side effects. In 9 out of 10 patients with preoperative malignant ascites, the ascites cleared after treatment. One-year survival rate was 54.2%. These encouraging preliminary results show that intraperitoneal chemohyperthermia with mitomycin C is a safe and reliable treatment for peritoneal carcinomatosis in far advanced digestive cancers.

Evidence for protein kinase C involvement in the short-term activation by prolactin of tyrosine hydroxylase in tuberoinfundibular dopaminergic neurons

The mechanism of the short-term activation by prolactin (PRL) of tyrosine hydroxylase (TH) in tuberoinfundibular dopaminergic neurons was examined in vitro on hypothalamic slices from ovariectomized rats. TH activity (determined by 3,4-dihydroxyphenylalanine accumulation in the median eminence after blockade of decarboxylase with NSD 1055) showed a dose-dependent increase within 2 h of incubation of the hypothalamic slices with PRL. To determine whether a phosphorylation process was involved in this increase in TH activity, we studied the sensitivity of the enzyme to dopamine (DA) feedback inhibition. In control median eminences, two kinetically different forms of TH coexisted, one exhibiting a Ki(DA) value of 29.92 +/- 0.49 microM, the other being approximately 15-fold more sensitive to DA inhibition with a Ki(DA) of 1.96 +/- 0.09 microM, likely corresponding to a phosphorylated and active form and to a nonphosphorylated and less active form, respectively. After PRL treatment, the TH form of low Ki(DA) remained unaffected, whereas the Ki(DA) of the purported active form of TH increased to 62.6 +/- 0.8 microM, suggesting an increase in the enzyme phosphorylation. This increase in the Ki(DA) of TH was selectively prevented by GF 109203X, a potent and selective inhibitor of protein kinase C, but not by a specific inhibitor of protein kinase A or calmodulin. Finally, this action of PRL could be mimicked by 12-O-tetradecanoylphorbol 13-acetate (a direct activator of protein kinase C). These results suggest that PRL, at the median eminence level, activates TH by increasing the enzyme phosphorylation and that this action may involve an activation of protein kinase C.

A new device for the treatment of pleural malignancies: intrapleural chemohyperthermia preliminary report

The prognosis of malignant pleural tumors remains extremely unfavorable. The aim of this study is to evaluate the combination of intrathoracic intrapleural chemotherapy and intrapleural hyperthermia (ITCH) in these diseases. Under anesthesia, 5 men were studied. After pleurectomy for mesothelioma (3/5) or adenocarcinoma (2/5), ITCH is carried out for over 60 min, either with mitomycin C (4/5) or cisplatin (1/5). No pre- or postoperative death occurred. The maximal pleural temperature is 42.6 degrees C. The blood level of mitomycin C never reached the systemic toxic level. All the patients were discharged from the surgical ward, 3 are still alive 15 months later. Therefore, ITCH appears to be a safe and reliable therapy.

Short-term inhibitory effect of estradiol on tyrosine hydroxylase activity in tuberoinfundibular dopaminergic neurons in vitro

The short-term inhibition by estradiol of tyrosine hydroxylase (TH) in tuberoinfundibular dopaminergic neurons was examined in vitro on hypothalamic slices from ovariectomized rats. TH activity (determined by L-3,4-dihydroxyphenylalanine accumulation in the median eminence after blockade of decarboxylase with NSD 1055) showed a 30-40% decrease within 1 h of incubation with estradiol. To determine whether a dephosphorylation process was involved in this decline in TH activity, we studied the sensitivity of the enzyme to dopamine (DA) feedback inhibition: In controls, we observed that two kinetically different forms of TH coexisted, with one exhibiting a Ki(DA) of 26.4 +/- 2 microM and the other being approximately 10-fold more sensitive to DA inhibition, with a Ki(DA) of 2.56 +/- 0.17 microM, likely corresponding to a phosphorylated and active form and to a nonphosphorylated and poorly active form, respectively. Conversely, after estradiol treatment all TH molecules exhibited the same Ki(DA) of 2.5 +/- 0.3 microM. This effect was stereospecific, because 17 alpha-estradiol could not promote it, whereas with 17 beta-estradiol, it could be observed at only 10(-11) M and after a short delay (30 min). Finally, this decrease in the Ki(DA) of the purported active form of TH could be prevented by okadaic acid (an inhibitor of protein phosphatases). These results suggest that estradiol can act directly on the mediobasal hypothalamus to trigger a rapid decline in TH activity and that this action may involve a decrease in TH phosphorylation.

Analysis of the human dopamine beta-hydroxylase promoter: transcriptional induction by cyclic AMP

We have analyzed some functional aspects of the promoter of the human dopamine beta-hydroxylase (DBH) gene. A fragment of 1,247 bp directly 5' to the transcriptional start was progressively shortened, placed in front of a reporter gene, and tested in a human neuroblastoma cell line expressing DBH (SK-N-SH-TFM) and in a monkey kidney cell line (CV-1). A remarkably short region (267 bp), directly upstream from the transcription start, was sufficient to confer activity and tissue-specific expression. Furthermore, the expression of the DBH gene was shown to be inducible by cyclic AMP in SK-N-SH-TFM cells. This effect was demonstrated to occur at the transcriptional level, as shown by run-on assays, and was due to the presence of a near-consensus cyclic AMP-responsive element located in the untranscribed 5' regulatory region of the gene.

Noradrenergic hyperactivity after partial fornix section: role in cholinergic dependent memory performance

Rats with unilateral or bilateral partial section of the fornix were impaired on an eight arm radial maze task. Neurochemical analysis of hippocampal tissue four weeks after the lesions revealed a 50% reduction of choline acetyltransferase (ChAT) activity. The cholinergic marker was correlated negatively with the number of errors in the maze; the lower the ChAT activity, the higher the error score. The fornix lesion also induced a 50% reduction in norepinephrine (NE), but no change in the noradrenergic metabolite methylhydroxyphenylglycol (MHPG), suggesting a net increase in turnover of NE in these animals. Additional lesion of the noradrenergic system with the neurotoxin DSP4 reduced both MHPG and NE levels by more than 90%, compared to nonlesioned controls, and reversed the behavioral deficit. This treatment had no further effect on cholinergic markers. There was a significant negative correlation between ChAT activity and the index of NE turnover, suggesting that hyperactivity in the noradrenergic system after fornix section inhibits the spared cholinergic function and thus exacerbates the cognitive deficit. The pattern of neurochemical results bear a striking resemblance to those seen in some Alzheimer's patients and suggest that an equilibrium among neurotransmitters is important to cognitive function.