No abstract

It can be concluded that nanostructured lipid carriers encapsulation may represent an effective strategy to prolong the half-life of bromocriptine.

]-5-HT over¯ow (EC 50 =64 nM; E max =31% inhibition), but its eect was partially antagonized by 10 mM naloxone. 5 It is concluded that the ORL 1 receptor is the most important presynaptic modulator of neocortical 5-HT release within the opioid receptor family. This suggests that the ORL 1 /nociceptin system may have a powerful role in the control of cerebral 5-HT-mediated biological functions.

Triple probe microdialysis was employed to investigate whether striatal NR2A and NR2B subunit containing NMDA receptors regulate the activity of striato-pallidal and striatonigral projection neurons. Probes were implanted in the striatum, ipsilateral globus pallidus and substantia nigra reticulata. Intrastriatal perfusion with the NR2A subunit selective antagonist (R)-[(S)-1-(4-bromo-phenyl)-ethylamino]-(2,3-dioxo-1,2,3,4-tetrahydroquinoxalin-5-yl)-methyl]-phosphonic acid (NVP-AAM077) reduced pallidal GABA and increased nigral glutamate (GLU) release whereas perfusion with the NR2B subunit selective antagonist (R-(R*,S*)-a-(4-hydroxyphenyl)-b-methyl-4-(phenylmethyl)-1-piperidinepropanol (Ro 25-6981) reduced nigral GABA and elevated striatal and pallidal GLU release. To confirm that changes in GABA levels were because of blockade of (GLUergic-driven) tonic activity of striatofugal neurons, tetrodotoxin was perfused in the striatum.Tetrodotoxin reduced both pallidal and nigral GABA release without changing GLU levels. To investigate whether striatal NR2A and NR2B subunits were also involved in phasic activation of striatofugal neurons, NVP-AAM077 and Ro 25-6981 were challenged against a NMDA concentration able to evoke GABA release in the three areas. Both antagonists prevented the NMDA-induced striatal GABA release. NVP-AAM077 also prevented the NMDA-induced surge in GABA release in the globus pallidus, whereas Ro 25-6981 attenuated it in the substantia nigra. We conclude that striatal NMDA receptors containing NR2A and NR2B subunits preferentially regulate the striato-pallidal and striato-nigral projection neurons, respectively. Keywords: GABA, glutamate, microdialysis, NMDA, NVP-AAM077, Ro 25-6981. The striatum represents the main afferent structure of the basal ganglia, receiving massive glutamatergic projections from the cerebral cortex and the thalamus. Striatal NMDA receptors, a subtype of glutamate (GLU) receptors, are key modulators of striatal functions and have been targeted in neurological disorders characterized by GLU receptor over activation (e.g. Parkinson's disease and L-DOPA-induced dyskinesia; Chase and Oh 2000; Hallett and Standaert 2004). NMDA receptors form a heterogeneous family of ligandgated ion channels assembled in a tetra/pentameric form by different combinations of eight splice variants of NR1 subunits and four isoforms (A-D) of NR2 subunits (Dingledine et al. 1999). In the striatum, projection neurons and interneurons express NMDA receptors, although the phenotype varies between cells (Landwehrmeyer et al. 1995;Standaert et al. 1999). This raises the possibility of a differential pharmacological modulation of striatal functions by subunit selective NMDA receptors ligands. The striatum modulates the activity of basal ganglia output nuclei via two pathways. Medium size GABAergic neurons originating from the matrix and projecting to the substantia nigra reticulata (SNr)/entopeduncular nucleus (the 'direct' pathway) or the globus pallidus (GP; the 'indirect' pathway) oppositely mo...

The effects of NMDA and a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) on endogenous acetyicholine release from rat striatal slices and synaptosomes were investigated. Both agonists (1-300 1iM) facilitated acetylcholine release from slices in a dosedependent manner. NMDA (100-300 pM) and AMPA (30-300 pM), however, subsequently inhibited acetylcholine release. NMDA (100 pM) -induced facilitation was antagonized by 3-(2-carboxypiperazin-4-yl) propyl-1phosphonic acid (CPP) and dizocilpine (both 1-10 pM), whereas the 10 pM AMPA effect was antagonized by 6cyano-7-nitroquinoxaline-2,3-dione (CNQX; 1 -30 pM). NMDA (100 pM) -induced inhibition was counteracted by CPP, but not dizocilpine, and by the nitric oxide synthase inhibitor L-nitroarginine (1-100 pM). Tetrodotoxin (0.5 pM) prevented the facilitatory effect of 3 p.M NMDA and AMPA, but left unchanged that of 30 pM NMDA and 100 pM AM PA. Acetylcholine release from synaptosomes was stimulated by KCI (7.5-100 mM) in a dose-dependent manner. NMDA and AMPA maximally potentiated the 20 mM KCI effect at 1 pM and 0.01 pM, but were ineffective at 100 pM and 10 pM, respectively. Inhibition of acetylcholine release was never found in synaptosomes. The effects of 1 pM NMDA and 0.01 pM AMPA were antagonized by CPP (0.0001-1 pM) or dizocilpine (0.0001-10 pM) and by CNQX (0.001-1 pM), respectively. These data suggest that glutamatergic control of striatal acetylcholine release is mediated via both pre-and postsynaptic NMDA and non-NMDA ionotropic receptors.

This study involves the histological analysis of samples taken during autopsies in cases of COVID-19 related death to evaluate the inflammatory cytokine response and the tissue localization of the virus in various organs. In all the selected cases, SARS-CoV-2 RT-PCR on swabs collected from the upper (nasopharynx and oropharynx) and/or the lower respiratory (trachea and primary bronchi) tracts were positive. Tissue localization of SARS-CoV-2 was detected using antibodies against the nucleoprotein and the spike protein. Overall, we tested the hypothesis that the overexpression of proinflammatory cytokines plays an important role in the development of COVID-19-associated pneumonia by estimating the expression of multiple cytokines (IL-1β, IL-6, IL-10, IL-15, TNF-α, and MCP-1), inflammatory cells (CD4, CD8, CD20, and CD45), and fibrinogen. Immunohistochemical staining showed that endothelial cells expressed IL-1β in lung samples obtained from the COVID-19 group (p < 0.001). Similarly, alveolar capillary endothelial cells showed strong and diffuse immunoreactivity for IL-6 and IL-15 in the COVID-19 group (p < 0.001). TNF-α showed a higher immunoreactivity in the COVID-19 group than in the control group (p < 0.001). CD8 + T cells where more numerous in the lung samples obtained from the COVID-19 group (p < 0.001). Current evidence suggests that a cytokine storm is the major cause of acute respiratory distress syndrome (ARDS) and multiple organ failure and is consistently linked with fatal outcomes.

Striatal cholinergic interneurons were recorded from a rat slice preparation. Synaptic potentials evoked by intrastriatal stimulation revealed three distinct components: a glutamatergic EPSP, a GABA(A)-mediated depolarizing potential, and an acetylcholine (ACh)-mediated IPSP. The responses to group II metabotropic glutamate (mGlu) receptor activation were investigated on the isolated components of the synaptic potentials. Each pharmacologically isolated component was reversibly reduced by bath-applied LY379268 and ((2S,1'R,2'R,3'R)-2-(2,3-dicarboxylcyclopropyl)-glycine, group II agonists. In an attempt to define the relevance of group II mGlu receptor activation on cholinergic transmission, we focused on the inhibitory effect on the IPSP, which was mimicked and occluded by omega-agatoxin IVA (omega-Aga-IVA), suggesting a modulation on P-type high-voltage-activated calcium channels. Spontaneous calcium-dependent plateau-potentials (PPs) were recorded with cesium-filled electrodes plus tetraethylammonium and TTX in the perfusing solution, and measurements of intracellular calcium [Ca2+]i changes were obtained simultaneously. PPs and the concomitant [Ca2+]i elevations were significantly reduced in amplitude and duration by LY379268. The mGlu-mediated inhibitory effect on PPs was mimicked by omega-Aga-IVA, suggesting an involvement of P-type channels. Moreover, electrically induced ACh release from striatal slices was reduced by mGlu2 receptor agonists and occluded by omega-Aga-IVA in a dose-dependent manner. Finally, double-labeling experiments combining mGlu2 receptor in situ hybridization and choline acetyltransferase immunocytochemistry revealed a strong mGlu2 receptor labeling on cholinergic interneurons, whereas single-label isotopic in situ hybridization for mGlu3 receptors did not show any labeling in these large striatal interneurons. These results suggest that the mGlu2 receptor-mediated modulatory action on cell excitability would tune striatal ACh release, representing an interesting target for pharmacological intervention in basal ganglia disorders.

The aim of the present microdialysis study was to investigate whether the increase in striatal glutamate levels induced by intrastriatal perfusion with NMDA was dependent on the activation of extrastriatal loops and/or endogenous striatal substance P and dopamine. The NMDA-evoked striatal glutamate release was mediated by selective activation of the NMDA receptor-channel complex and action potential propagation, as it was prevented by local perfusion with dizocilpine and tetrodotoxin, respectively. Tetrodotoxin and bicuculline, perfused distally in the substantia nigra reticulata, prevented the NMDA-evoked striatal glutamate release, suggesting its dependence on ongoing neuronal activity and GABA A receptor activation, respectively, in the substantia nigra. The NMDA-evoked glutamate release was also dependent on striatal substance P and dopamine, as it was antagonized by intrastriatal perfusion with selective NK 1 (SR140333), D 1 -like (SCH23390) and D 2 -like (raclopride) receptor antagonists, as well as by striatal dopamine depletion. Furthermore, impairment of dopaminergic transmission unmasked a glutamatergic stimulation by submicromolar NMDA concentrations. We conclude that in vivo the NMDA-evoked striatal glutamate release is mediated by activation of striatofugal GABAergic neurons and requires activation of striatal NK 1 and dopamine receptors. Endogenous striatal dopamine inhibits or potentiates the NMDA action depending on the strength of the excitatory stimulus (i.e. the NMDA concentration). Keywords: dopamine, glutamate, 6-hydroxydopamine, microdialysis, NMDA, substance P. The most consistent finding across microdialysis studies focused on NMDA actions in the basal ganglia is that striatal perfusion with NMDA elevates local glutamate (GLU) extracellular levels. This increase has been detected both in awake (Young and Bradford 1991;Carboni et al. 1993;Liu and Moghaddam 1995;Morari et al. 1996;Bogdanov and Wurtman 1997;Rossetti et al. 1999;Yamamoto et al. 1999;Hashimoto et al. 2000) and anaesthetised (Bustos et al. 1992;Morari et al. 1993;Kendrick et al. 1996;Abarca and Bustos 1999;Bert et al. 2002) rats. In spite of such a large number of reports, the nature of glutamate release evoked by NMDA in the striatum remains controversial. The mechanisms proposed point to either stimulation of NMDA autoreceptors, which would directly enhance neurosecretion from striatal afferent GLUergic terminals, or stimulation of postsynaptic NMDA receptors, which would indirectly increase GLU levels by releasing intrastriatal modulators (e.g. nitric oxide) or activation of extrastriatal loops. Indeed, our previous observations (Morari et al. 1996(Morari et al. , 1998bMarti et al. 2002) that striatal NMDA perfusion elevates, not only GLU release locally in the striatum, but also GLU and GABA release distally in the substantia nigra reticulata