Risk assessment on the use of herbal medicinal products containing pyrrolizidine alkaloids.

Pyrrolizidine alkaloids (PA) are common plantal toxins directed against insect herbivores. Unsaturated PAs are known to be hepatotoxic. Many of the PAs are in addition mutagenic and some may possibly be carcinogenic for humans.

An update on drug treatment options of Alzheimer's disease.

Alzheimer's disease (AD) is characterized by progressive decrease in cognitive function and loss of short-term memory known to be associated with a dysfunction of the cholinergic system. The pathological hallmarks of AD are beta-amyloid (Abeta) plaques and neurofibrillary tangles (NFTs) consisting of hyperphosphorylated tau. Hypercholesterolemia and disturbances in glucose metabolism are another risk factors.

GABAA receptor pharmacology of fluorinated derivatives of the novel sedative-hypnotic pyrazolopyrimidine indiplon.

The function of gamma-aminobutyric acid type A receptors (GABA(A) receptors) is enhanced by various clinically important drugs including benzodiazepines that act on an allosteric site formed at the interface between the alpha and gamma subunits. In contrast to classical benzodiazepines, the novel pyrazolopyrimidine indiplon (N-methyl-N-{3-[7-(thiophene-2-carbonyl)-1,5,9-triazabicyclo[4.3.

Implication of the transcription factor E2F-1 in the modulation of neuronal apoptosis.

Neurodegenerative diseases as Alzheimer's disease, Parkinson's disease and other neurological disorders remain major problem worldwide since is currently no effective treatment. Thus, studying the mechanisms involved in neuronal apoptotic pathways is imperative if drugs that might stop or delay these disease processes are to be synthesized. In recent years it has become evident that mitochondria are key component of the neuronal apoptotic route.

Auto-modulation of neuroactive steroids on GABA A receptors: a novel pharmacological effect.

GABA(A) receptor function is modulated by various important drugs including neuroactive steroids that act on allosteric modulatory sites and can directly activate GABA(A) receptor channels at high concentrations. We used whole cell patch-clamp recordings and rapid applications of the neuroactive steroid alphaxalone to investigate repetitive steroid effects. Alphaxalone potentiation of submaximal GABA-evoked currents was enhanced significantly by repetitive coapplications at all investigated recombinant isoforms (alpha1beta3delta, alpha1beta3gamma2L, alpha6beta3delta, alpha6beta3gamma2L) and at GABA(A) receptors of differentiated human NT2 neurons.

Different capacities of various NMDA receptor antagonists to prevent ischemia-induced neurodegeneration in human cultured NT2 neurons.

In the present study, human NT2 neurons obtained from embryonic teratocarcinoma (NT2) cells were established as human in-vitro model to investigate the mechanisms associated with hypoxia/ischemia-induced neuronal injury. NT2 neurons express functional NMDA receptors that are of particular significance for hypoxia/ischemia-related neuronal damage. In patch-clamp recordings under normoxic conditions, NMDA (plus 10 microM glycine)-induced inward currents (EC(50)=43.

Carbonyl stress and NMDA receptor activation contribute to methylglyoxal neurotoxicity.

Methylglyoxal (MG) is a reactive alpha-ketoaldehyde physiologically generated as a by-product of glycolysis. MG that is able to form protein adducts resulting in advanced glycation end products accumulates under conditions associated with neurodegeneration such as impaired glucose metabolism or oxidative stress. In the present study, short-term exposure of human neuroblastoma SH-SY5Y cells to MG was associated with an early depolarization of the plasma membrane, glutamate release, and formation of reactive oxygen species.

Neuroprotection associated with alternative splicing of NMDA receptors in rat cortical neurons.

Exposure of cultured cortical neurons to elevated extracellular K(+) concentrations (25 mM) induces membrane depolarization and an increase in action-potential firing. Long-term high K(+) treatment was associated with an increased neuronal cell death. In surviving neurons, multiple changes occurred in the proportion of individual NMDA receptor subunit 1 (NR1) splice variant mRNA expression, whereas the overall expression of NR1, NR2A and NR2B transcripts remained unaffected.

Evaluation of the neuronal apoptotic pathways involved in cytoskeletal disruption-induced apoptosis.

The cytoskeleton is critical to neuronal functioning and survival. Cytoskeletal alterations are involved in several neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. We studied the possible pathways involved in colchicine-induced apoptosis in cerebellar granule neurons (CGNs).

Adenine nucleotides inhibit recombinant N-type calcium channels via G protein-coupled mechanisms in HEK 293 cells; involvement of the P2Y13 receptor-type.

1. N-type Ca(2+) channel modulation by an endogenous P2Y receptor was investigated by the whole-cell patch-clamp method in HEK 293 cells transfected with the functional rabbit N-type calcium channel. 2.

Subsensitivity of P2X but not vanilloid 1 receptors in dorsal root ganglia of rats caused by cyclophosphamide cystitis.

The application of cyclophosphamide to rats was used to induce interstitial cystitis. Behavioural studies indicated a strong pain reaction that developed within 2 h and levelled off thereafter causing a constant pain during the following 18 h. Neurons prepared from L6/S1 dorsal root ganglia innervating the urinary bladder responded to the application of capsaicin or alpha,beta-methylene ATP (alpha,beta-meATP) with an increase of intracellular Ca2+ ([Ca2+]i).

Characterization of P2X3, P2Y1 and P2Y4 receptors in cultured HEK293-hP2X3 cells and their inhibition by ethanol and trichloroethanol.

Membrane currents and changes in the intracellular Ca2+ concentration ([Ca2+]i) were measured in HEK293 cells transfected with the human P2X3 receptor (HEK293-hP2X3). RT-PCR and immunocytochemistry indicated the additional presence of endogenous P2Y1 and to some extent P2Y4 receptors. P2 receptor agonists induced inward currents in HEK293-hP2X3 cells with the rank order of potency alpha,beta-meATP approximately ATP > ADP-beta-S > UTP.

5,7-Dihydroxytryptamine--a selective marker of dopaminergic or serotonergic neurons?

The aim of the present study was to investigate whether 5,7-dihydroxytryptamine (5,7-DHT), an autofluorescent serotonin derivative, can be used as a specific marker for serotonergic or dopaminergic neurons in rat mesencephalic cultures. To this end, primary cultures were prepared from the ventral brain stem of 14-day-old Wistar rat foetuses and kept in culture for 10 days (DIV10). At DIV10, the cultures were characterized immunocytochemically with antibodies raised against tyrosine hydroxylase (TH; a marker for catecholaminergic/ dopaminergic neurons) and serotonin (5-HT).

AMPA-induced Ca(2+) influx in cultured rat cortical nonpyramidal neurones: pharmacological characterization using fura-2 microfluorimetry.

Immunocytochemical and Co(2+) uptake studies revealed that in primary cultures of rat cortical neurones, the majority of neurones are gamma-aminobutyric acid (GABA) immunopositive and can express Ca(2+)-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors. By fura-2 microfluorimetry, it was shown that the stimulation with the selective agonist (S)-AMPA (0.3-300 microM) induced a concentration-dependent but cell-variable increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) (EC(50) value 7.