Neuroprotective effect of thyrotropin-releasing hormone against excitatory amino acid-induced cell death in hippocampal slices

Thyrotropin-releasing hormone (TRH) and some of its stable analogues have recently been shown to improve functional recovery after neurologic dysfunctions, such as brain trauma and epilepsy, in both animals and humans. The exact mechanism by which TRH produces its neuroprotective effects is still uncertain. The present study provides the first evidence that TRH exerts a neuroprotective effect against N-methyl-D-aspartate (NMDA)-mediated excitotoxicity in rat hippocampal slices. TRH concentration dependently reduced NMDA toxicity by a mechanism that was highly sensitive to the protein kinase C blocker, bisindolilmaleimide. Delayed application of TRH, during NMDA exposure, still produced neuroprotection.

Priming of cultured neurons with sabeluzole results in long-lasting inhibition of neurotoxin-induced tau expression and cell death

Sabeluzole was described to have antiischemic, antiepileptic, and cognitive-enhancing properties, and is currently under development for Alzheimer's disease. Recently, it was reported that repeated treatments with sabeluzole protect cultured rat hippocampal neurons against NMDA- and glutamate-induced neurotoxicity. We evaluated the possibility that sabeluzole elicits neuroprotection by acting, either directly or indirectly, on tau proteins. We found that repeated treatments during development of primary cultures of cerebellar granule cells with nanomolar concentrations of sabeluzole resulted in mature cells that were resistant to the excitotoxicity induced by glutamate. Also, sabeluzole treatment specifically prevented the glutamate-induced increase of tau expression without modifying the basal pattern of expression of tau proteins, as shown by measurement of mRNA and protein levels. In human neuroblastoma cell line SH-SY5Y, differentiated by treatment with retinoic acid, doxorubicin increased tau immunoreactivity, and later induced cell death. Both effects were prevented by sabeluzole. Our data indicate that increased tau expression is a common response to different types of cells to neurotoxic agents, and that sabeluzole-induced neuroprotection is functionally associated with the prevention of the injury-mediated increase of tau expression.

Neuroprotection by aspirin and sodium salicylate through blockade of NF-kappaB activation

Aspirin (acetylsalicylic acid) is a commonly prescribed drug with a wide pharmacological spectrum. At concentrations compatible with amounts in plasma during chronic anti-inflammatory therapy, acetylsalicylic acid and its metabolite sodium salicylate were found to be protective against neurotoxicity elicited by the excitatory amino acid glutamate in rat primary neuronal cultures and hippocampal slices. The site of action of the drugs appeared to be downstream of glutamate receptors and to involve specific inhibition of glutamate-mediated induction of nuclear factor kappa B. These results may contribute to the emerging theme of anti-inflammatory drugs and neurodegeneration.

Activation of multiple metabotropic glutamate receptor subtypes prevents NMDA-induced excitotoxicity in rat hippocampal slices

Metabotropic glutamate receptors (mGluRs) belong to a relative large receptor family consisting of multiple members with important roles in a number of brain functions. We report here that activation of mGluRs prevents the neurotoxic effect induced by N-methyl-D-aspartate (NMDA) in slices from the rat hippocampus. Neuroprotection was elicited when slices were simultaneously exposed to both the selective mGluR agonist (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (tACPD) and NMDA. Persisting stimulation of mGluRs after the toxic exposure did not improve the survival of pyramidal or granular cells. The neuroprotection elicited by tACPD toxic exposure did not improve the survival of pyramidal or granular cells. The neuroprotection elicited by tACPD was also evoked by its active isomer, (1S, 3R)-ACPD, and was prevented by the selective mGluR antagonist (+)-alpha-methyl-4-carboxyphenyl-glycine (500 microM), confirming that mGluR activation is involved in the mechanism of action of tACPD. The effect of 100 microM tACPD was reproduced by 100 microM quisqualate, an agonist of mGluR2 and mGluR3 subtypes. No neuroprotection was induced by L-2-amino-4-phosphonobutyrate, a selective agonist for mGluR4, mGluR6, mGluR7 and mGluR8, at 500 microM. Since the NMDA-mediated cell death in hippocampal slices is considered relevant to ischaemia-induced brain injury, these results indicate that mGluRs may be important safety devices used by neurons to decrease their sensitivity to excitotoxic stimuli and increase their chance of survival.

Metabotropic and ionotropic transducers of glutamate signal inversely control cytoplasmic Ca2+ concentration and excitotoxicity in cultured cerebellar granule cells: pivotal role of protein kinase C

We investigated the functional role of metabotropic glutamate receptors (mGluRs) in modulating glutamate-affected neuronal intracellular calcium concentration ([Ca2+]i) and cell viability in rat cerebellar granule cells. The mGluR agonist trans-1-amino-cyclopentane-1,3-dicarboxylic acid (tACPD) induced a transient increase in [Ca2+]i, which seemed to be developmentally regulated and maximal at 4 days in vitro. In addition, tACPD significantly prevented the [Ca2+]i rise produced by glutamate or by N-methyl-D-aspartate. The mGluR antagonists L-2-amino-3-phosphonopropionic and (+)-alpha-methyl-4-carboxyphenylglycine blocked the effects of tACPD but intrinsically, they magnified the glutamate-mediated [Ca2+]i elevation. The tACPD-mediated decrease in [Ca2+]i rise occurred under experimental conditions superimposable on those producing neuroprotection in glutamate-exposed cultures. tACPD affected neither [Ca2+]i elevation due to KCI nor that evoked by the calcium ionophore A 23187. The inhibitory effect of tACPD was also unaffected by K+ channel blockade produced by tetraethylammonium. The tACPD effects were fully mimicked by quisqualate and (RS)-3,5-dihydroxyphenylglycine, whereas they were only partially reproduced by (2S,1'S,2'S)-2-carboxycyclopropyl-glycine. L-2-Amino-4-phosphonobutyrate was inactive in preventing glutamate-mediated [Ca2+]i rise and neurotoxicity. The tACPD inhibitory responses seemed to be highly sensitive to protein kinase C blockade by bisindolylmaleimide or staurosporine, whereas they were weakly affected by the cAMP analogue dibutyryl cAMP. The protein kinase C activator 4beta-phorbol-12,13-dibutyrate reproduced mGluR-mediated inhibition of both glutamate-induced [Ca2+]i rise and neurotoxicity. In summary, these data suggest that activation of mGluR1-5 subtypes reduce glutamate-mediated (Ca2+]i rise through a mechanism involving protein kinase C activation. Such an effect results in neuroprotection.

Quality assurance of clinical transfusion practice by implementation of the privilege of blood prescription and computerized prospective audit of blood requests

Guidelines, algorithms and recommendations have been issued in the attempt to ensure appropriateness of transfusion practice, but the results are less than satisfactory, mainly due to the difficulty to turn paper procedures into actual practice. In our hospital we have tried to overcome this difficulty through the implementation of a quality assurance programme which includes giving the privilege of nonurgent blood prescription to a limited number of physicians and a computerized prospective audit of blood requests. The latter is performed through verification of the compliance of blood requests, which are designed to include a patient's laboratory and clinical data, with hospital guidelines for the proper use of blood. In the 12 months since implementation of the computerized prospective audit the transfusion service has evaluated 7884 requests. Of these, 63.4% (n = 4998) were for red blood cells, 21.1% (n = 1664) for platelets and 15.5% (n = 1222) for fresh frozen plasma. The prospective audit showed that 96.8% and 98.1% of requests for red units and platelets were appropriate, respectively. Conversely, approximately 27% of plasma requests did not comply with guidelines, mainly because the evidence of coagulopathy was missing. However, inappropriateness of plasma requests for elective general surgery decreased from 39% at the onset of the programme to 14% in the last trimester considered. Moreover, the evaluation by retrospective audit of the proportion of patients transfused with both red blood cells and plasma in the perioperative period out of those transfused with red blood cells only, as an indicator of unwanted reconstitution of whole blood, showed that this proportion decreased from 47.6% (320/672) in the 12 months before implementation of computerized audit to 37.8% (244/646) in the following 12 months (difference = -9.8%, 95% confidence interval of the difference from -4.5% to -15.1%; P < 0.005 by chi 2 test). Our initial experience, together with the present system, shows that (1) the restriction of nonurgent blood prescription to a group of clinicians more educated in transfusion medicine than average clinicians practicing in a large multispecialty hospital is feasible; (2) prospective audit is a useful tool for assuring the quality of blood requesting.

Differential expression of fetal and mature tau isoforms in primary cultures of rat cerebellar granule cells during differentiation in vitro

The molecular mechanism(s) responsible for the differential expression of various tau protein isoforms as well as their functional role in morphogenesis, neurofibrillary tangle formation and neurodegeneration have not been completely clarified. We found that the expression of tau proteins in primary cultures of cerebellar granule cells from neonatal rat brain is a developmentally regulated process affecting tau synthesis at different levels. Changes in tau RNA splicing are clearly demonstrated by PCR data showing the switching on of the mRNA containing four internal repeats by DIV 6 and the switching off of the mRNA containing three internal repeats after DIV 12. The changes in mRNA levels of the different tau isoforms during development in vitro occur in parallel with changes in tau protein expression, both qualitatively and quantitatively, as shown by Western analysis of protein extracts from granule cells at different DIV with an anti-tau polyclonal antibody. Finally, as indicated by MAP2 and tau immunocytochemistry data, the switch in tau protein expression appears to be contemporary with neurite outgrowth and cell differentiation. Our data suggest that a differential expression of various tau proteins parallels the degree of cell maturation.

Inhibition of glutamate-induced neurotoxicity by a tau antisense oligonucleotide in primary culture of rat cerebellar granule cells

Short-term exposure of primary cultures of cerebellar granule cells from neonatal rat brain to high concentrations of glutamate resulted in a significant increase of both immunoreactivity to and mRNA levels of tau protein. Time-course experiments revealed the increases of tau immunoreactivity and mRNA levels to be maximal 2 h after the glutamate pulse. To investigate the relationship between newly synthesized tau protein and glutamate-induced neurotoxicity, neurons were preincubated with a specific tau antisense oligonucleotide. This treatment resulted in (i) inhibition of the glutamate-induced increase of tau immunoreactivity and (ii) a decrease in the sensitivity of the neurons to neurotoxic concentrations of glutamate. These data indicate that induction of the cytoskeleton-associated tau protein participates in the cascade of events promoted by glutamate leading to neurodegeneration.

Opposing regulation of amyloid precursor protein by ionotropic and metabotropic glutamate receptors

The effects of the ionotropic glutamate receptor (iGluR) selective agonist N-methyl-D-aspartate (NMDA) on amyloid precursor protein (APP) levels were investigated in primary cultures of rat cerebellar granule cells. Both immunocytochemistry and immunoblotting techniques showed increased APP levels 4 h after a 15 min pulse with NMDA. This effect was completely prevented by incubating the neurones in the presence of the selective metabotropic GluR (mGluR) agonist 1S,3R-ACPD. This phenomenon was related, in terms of doses and time, with the observed 1S,3R-ACPD-mediated protection on NMDA-induced granule cell death. Our findings indicate that APP metabolism is differentially regulated by the stimulation of various GluR subtypes. The GluR-mediated changes in APP content might participate in the control of neuronal viability.

N-methyl-D-aspartate neurotoxicity in hippocampal slices: protection by aniracetam

Aniracetam, a drug known to elicit cognition enhancing properties in both animals and humans, was found to counteract the neurotoxicity induced by excitatory amino acids in primary cultures of cerebellar neurons. We report here that aniracetam prevents the neurotoxic effect induced by N-methyl-D-aspartate (NMDA) in rat hippocampal slices. Time-course experiments showed that the aniracetam-induced neuroprotection does not require preincubation of the slices with the drug. Maximal effective concentration of aniracetam was 10 microM. Since the NMDA-mediated cell death in hippocampal slices is considered a valuable experimental model of ischemia, these results suggest a possible novel therapeutic application for aniracetam.

Antisense strategy unravels tau proteins as molecular risk factors for glutamate-induced neurodegeneration

1. We investigated the possible involvement of tau proteins in the neurotoxic process activated by glutamate using the oligonucleotide antisense strategy. 2. We found that pretreatment of granule cells with an antisense oligonucleotide of the tau gene completely prevented the increase in tau immunoreactivity induced by glutamate. 3. A significant amount of the tau antisense oligonucleotide (about 1 to 2% of total) was taken up by the cells and remained stable in the cells for at least 60 min. A dose-response study revealed that 25 microM tau antisense oligonucleotide was the most efficacious concentration in terms of prevention of glutamate-induced tau immunoreactivity increases, without affecting basal tau expression. Higher concentrations of tau oligonucleotide antisense reduced tau immunoreactivity in control cells. 4. Significantly, the concentration-response curve of glutamate for inducing neuronal death in cells pretreated with tau antisense oligonucleotide showed a shift to the right compared to those obtained in untreated or tau sense oligonucleotide-treated cells. 5. Since inhibition of tau synthesis does not completely prevent but only decreases the neuronal sensitivity to glutamate, it is tempting to speculate that accumulation of tau within the neuron in response to glutamate represents one of the molecular risk factors lowering the safety margin of neurons to excitotoxic-induced injury.

Lack of vasoactive intestinal peptide-releasing property in prolactin cells from ovariectomized rats: contribution of post-transductional impairments

We have demonstrated recently that in menopausal women and in ovariectomized rats the deficiency of circulating oestrogens impairs vasoactive intestinal peptide (VIP) efficacy in stimulating prolactin (PRL) release. The present study was designed to investigate whether the lack of VIP-induced PRL release after ovariectomy is a consequence of a defect at the receptor-transductional or post-transductional level. For this purpose we evaluated the VIP receptor function, by measuring VIP-stimulated cyclic adenosine monophosphate (AMP) formation, and the efficacy of the cyclic AMP-dependent PRL release in pituitary cells from control and ovariectomized animals. We observed that VIP induced a significantly higher stimulation of adenylate cyclase in pituitary homogenates from ovariectomized rats than in those from control animals. This effect appeared to be linked to an increased efficiency of the Gs coupling protein, because superimposable results were obtained by using the non-hydrolysable guanosine triphosphate (GTP) analogue, 5-guanylylimidodiphosphate. On the contrary, the cyclic AMP analogue, 8-Br-cAMP, that potently stimulated PRL release from control pituitary cells was completely ineffective in cells from ovariectomized rats. The present data indicate that in PRL-secreting cells from ovariectomized rats a defect in the post-transductional mechanism that couples the VIP receptor to PRL secretion, rather than a reduction of receptor function, possibly accounts for the lack of VIP efficacy.

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate and kainate differently affect neuronal cytoarchitecture of rat cerebellar granule cells

Rat cerebellar granule cells cultured in media containing 12 mM KCl showed short life-span, did not branch, and died after 10 days in vitro. The cell exposure to N-methyl-D-aspartate (NMDA) or to kainate promoted both neuron survival and branching, reproducing the viability and the neurite extension routinely observed in cultures maintained in media containing 25 mM KCl. Exposure of neurons to alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) resulted in an increased survival not associated with neuritic arborization. These results suggest that the glutamate ionotropic receptor subtypes differently contribute in elaborating neuronal morphogenesis.

Temporal lobe epilepsy in early childhood

To explore the electroclinical features of temporal lobe epilepsy (TLE) in early childhood, we studied results of video-EEG and other tests of 14 children aged 16 months to 12 years selected by seizure-free outcome after temporal lobectomy. Four children had mesiotemporal sclerosis, 1 had cortical dysplasia, and 9 had low-grade temporal neoplasms. The children had complex partial seizures (CPS) with symptomatology similar to that of adults with TLE, including decreased responsiveness and automatisms. Automatisms tended to be simpler in the younger children, typically limited to lip smacking and fumbling hand gestures. Scalp/sphenoidal EEG showed anterior/inferior temporal interictal sharp waves and unilateral temporal seizure onset in the 4 children with mesiotemporal sclerosis and in the child with cortical dysplasia, but EEG findings in 9 children with low-grade temporal tumors were complex, including multifocal interictal sharp waves or poorly localized or falsely lateralized EEG seizure onset. In children without tumors, video-EEG was critical to localization of the epileptogenic zone for resection, but in patients with tumors video-EEG was less localizing and its main value was to confirm that the reported behaviors were epileptic seizures with semiology typical of temporal lobe onset.

Attenuation of excitatory amino acid toxicity by metabotropic glutamate receptor agonists and aniracetam in primary cultures of cerebellar granule cells

Activation of glutamate ionotropic receptors represents the primary event in the neurotoxicity process triggered by excitatory amino acids. We demonstrate here that the concentration-dependent stimulation of metabotropic glutamate receptor (mGluR) by the selective agonist trans-1-aminocyclopentane-1,3-dicarboxylate or by quisqualate counteracts both glutamate- and kainate-induced neurotoxicity in primary cultures of rat cerebellar granule cells. The mGluR-evoked responses are potentiated by aniracetam, which per se also elicits neuroprotection. Aniracetam concentration-dependently counteracted glutamate-, kainate-, or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-induced cell death and greatly facilitated neuroprotective response achieved by different concentrations of both quisqualate and trans-1-aminocyclopentane-1,3-dicarboxylate. In addition, aniracetam potentiated the mGluR-coupled stimulation of phospholipase C, as revealed by the measurement of 3H-inositol phosphate formation. Thus, mGluRs could be a suitable target for novel pharmacological strategies pointing to the treatment of neurodegenerative diseases.

A Tau antisense oligonucleotide decreases neurone sensitivity to excitotoxic injury

Short-term exposure of primary cultures of cerebellar granule cells from neonatal rat brain to high concentrations of glutamate results in neuronal degeneration. We found that glutamate, before causing neuronal degeneration, induced a significant increase of Tau protein immunostaining. Time-course experiments revealed the increase ot Tau immunoreactivity to be maximal 2 h after the glutamate pulse. To investigate the possible role of newly synthesized Tau protein in the neurotoxic process activated by glutamate, cerebellar granule cells were preincubated with a specific Tau antisense oligonucleotide. This treatment resulted in (i) an inhibition of the glutamate-induced increase of Tau immunoreactivity and (ii) a decrease in the sensitivity of the neurones to neurotoxic concentrations of glutamate. These data indicate that new synthesis of the cytoskeleton-associated Tau protein is a crucial step in the cascade of events promoted by glutamate and leading to neurodegeneration.

Women, HIV infection, and AIDS: tapestries of life, death, and empowerment

Women, the minority population in the human immunodeficiency virus (HIV) pandemic, are fast becoming one of the highest subgroups to be infected and affected by the disease. In the United States, most of these women are black or Hispanic, poor and urban dwellers, and addicted to drugs. This paper discusses the physical, psychological, and social manifestations of HIV disease in women, such as diminished activity tolerance, neurologic or cognitive changes, occupational and social role imbalance, and stigma and discrimination, and describes the sociocultural aspects of women's lives for assessment and treatment of women with HIV. Health promotion, education, and AIDS prevention and wellness programming are emphasized as strategies toward facilitation of self-empowerment for women with HIV disease. These health promotion and wellness strategies include learning of new and adaptation of current roles; learning strategies for self-care that include care for one's physical, psychosocial, spiritual, and sexual health; and learning and developing action plans toward healthy living and self-empowerment.

Tolerance to hypoactivity and sensitization to hyperactivity after chronic treatment with a presynaptic dose of lisuride in rats

We studied the adaptive changes of the locomotor effects of lisuride, a selective agonist for dopamine (DA) D2 receptors, and the functional state of D1 and D2 receptors after repeated administration of lisuride at a dose supposed to act preferentially on DA autoreceptors. Rats were treated daily with saline or lisuride, at a dose that causes a significant reduction in locomotor activity when given to naive rats (25 micrograms/kg i.p.), for 33 days and the effect of different challenging doses of the drug on locomotor activity was measured at different times during and after the treatment. The functional state of D1 and D2 DA receptors was evaluated by measuring SKF 82526-stimulated and LY 171555-inhibited adenylate cyclase (AC) activity in the caudatus/putamen, nucleus accumbens and substantia nigra and naive and chronically treated rats. There was a progressive decline in the ability of lisuride to decrease locomotor activity in rats given daily injections of lisuride, and there was a marked reduction in the threshold dose of lisuride for causing hypermotility. The functional state of DA receptors, positively or negatively linked to AC activity, was not modified by the treatment. The most suitable explanation of the reported adaptive behavioral changes is a down-regulation of DA autoreceptors after chronic treatment with presynaptic doses of lisuride.

Requirement of oestrogens for the sensitivity of prolactin cells to vasoactive intestinal peptide in rats and man

Vasoactive intestinal peptide (VIP) is a prolactin-releasing hormone which is involved in the multifactorial modulation of prolactin secretion in mammals. Intravenous injection of VIP (1 microgram/kg) to fertile women increased plasma prolactin levels and heart rate and reduced diastolic pressure. The same treatment to menopausal women caused similar cardiovascular effects but did not modify plasma prolactin levels. In contrast, TRH (200 micrograms, i.v.) induced a significant increase in plasma prolactin levels in both fertile and menopausal women. The relevance of oestrogens in affecting VIP-stimulated prolactin secretion was evaluated in vitro by measuring prolactin release from pituitary cells of control and ovariectomized rats. The sensitivity of rat mammotrophs to VIP, but not to TRH, was completely suppressed 3 or 4 weeks after ovariectomy. Furthermore, implantation of rats with a silastic capsule containing oestradiol-17 beta during ovariectomy, preserved the cell responsiveness to VIP. The prolactin-releasing property of VIP was also restored when pituitary cells from ovariectomized rats were cultured for 3 days in the presence of 10 nmol oestradiol-17 beta/l before being used for prolactin release experiments. The present study shows that the ability of prolactin-secreting cells to respond to the stimulatory action of VIP requires high levels of circulating oestrogens, both in man and rats.

Various Ca2+ entry blockers prevent glutamate-induced neurotoxicity

In the present study we investigated the effect of different Ca2+ entry blockers on the onset of neuronal damage induced by glutamate, kainate or alpha-amino-3-hydroxy-5-methyl-5-isoxazolo propionate (AMPA) in primary culture of rat cerebellar granule cells. We found that the dihydropyridine derivative, nifedipine used at 100 nM concentration, significantly counteracted the neuronal death induced by 15 min application of 50 microM glutamate. This effect was dependent on the presence of nifedipine before the exposure of granule cells to glutamate and was dose-related (IC50 = 10 nM). The nifedipine response was reproduced by isradipine and by verapamil with IC50 values of 9 and 100 nM, respectively. The activation of voltage sensitive Ca2+ channels elicited by 100 nM Bay K 8644, greatly enhanced glutamate-mediated neurotoxicity. Moreover, 100 nM isradipine was significantly active in blocking the neuronal death produced by 24 h exposure of cerebellar granule cells to 10 microM AMPA or 60 microM kainate. These results reveal a 'preventive' role of the Ca2+ entry blockers on the development of the neurodegeneration induced by overstimulation of various glutamate receptor subtypes.

Characterization of monoaminergic receptors in hypothalamic nuclei mediating feeding behavior in rats

It has been proposed that receptors mediating the action of dopamine (DA), serotonin and norepinephrine exist in the hypothalamus to control feeding behavior in the rat. To further characterize the receptor subtypes involved in this phenomenon and determine their locus within specific hypothalamic nuclei, measurements of adenylate cyclase (AC) activity, as a biochemical index of monoaminergic receptors, were taken after administration of various monoaminergic agonists and antagonists. It was first found that DA and selective D2 agonists, such as quinpirole and lisuride, strongly reduced AC activity in homogenates from the lateral perifornical hypothalamus (PFH), where previous evidence has shown DA agonists to inhibit feeding. These inhibitory effects were stereospecifically antagonized by the D2 antagonist (-)-sulpiride. The selective D1 agonist SKF 82526, up to 100 microM, was completely inactive in modifying the basal enzyme function in PFH. In homogenates from rat paraventricular nucleus (PVN), DA (100 microM), quinpirole (10 microM) and SKF 82526 (100 microM) were unable to affect AC activity, consistent with previous pharmacological evidence showing DA in the PVN to have no effect on feeding. These results suggest the presence of D2 receptors in the PFH but not in the PVN and the absence of D1 receptors in both areas. Under the same experimental conditions, the alpha 2 adrenoceptor agonist clonidine was able to inhibit AC in the PVN, and this effect was reversed by the alpha adrenoceptor antagonist phenoxybenzamine. These results supported the previously described PVN alpha 2 adrenergic system.(ABSTRACT TRUNCATED AT 250 WORDS)