Receptores nicotínicos da acetilcolina são encontrados na retina de pintos desde o início do desenvolvimento embrionário. As propostas desse trabalho foram caracterizar esses receptores no desenvolvimento de células de retinas embrionárias de pinto com oito dias, em cultura, e investigar se luzindole, um antagonista de receptores de melatonina, interfere com a atividade, distribuição e número desses receptores. Os ensaios funcionais foram feitos através de microfisiometria, método no qual é medido o aumento da velocidade de acidificação do meio extracelular de células em cultura, provocado pela ativação de receptores por agonistas. Os resultados são expressos como o percentual de aumento da velocidade de acidificação do meio extracelular acetilcolina-estimulado sobre a velocidade de acidificação do meio extracelular basal (ECAR % basal). A eficácia da acetilcolina aumentou do quarto dia de cultura para o quinto dia, decaindo ao oitavo dia, sendo bloqueada de modo dependente de concentração por dihidro-β-eritroidina (a partir de 10 µM), ao quarto dia e por α-bungarotoxina (10nM), ao quinto e sexto dia de cultivo, não ocorrendo o inverso. Para os ensaios de ligação, utilizou-se [125I] α-bungarotoxina, e ao quarto dia de cultivo houve maior número de sítios, menor afinidade e maior grau de cooperatividade. Ao quinto dia de cultivo ocorreu o inverso. Foi investigado, por imunocitoquímica, o desenvolvimento da distribuição da imunorreatividade para as subunidades α3 e α8 e ambas foram encontradas em culturas de quatro e seis dias, estando α3 principalmente em corpos neuronais e dendritos proximais e α8 principalmente em prolongamentos. O tratamento crônico com luzindole não interferiu com o padrão de distribuição das subunidades α3 e α8 em culturas de quatro ou seis dias, em nenhum tempo de cultivo. Também não interferiu no número de sítios, na constante de associação e no tempo de equilíbrio da ligação de [125I] α-bungarotoxina, nas culturas cultivadas por cinco dias. Entretanto, a resposta à acetilcolina em culturas de cinco e seis dias foi inibida de modo concentração e tempo dependente por luzindole, sem apresentar somação com a inibição por α-bungarotoxina. Concluiu-se que na cultura de células de retina a eficácia do agonista acetilcolina é dependente do desenvolvimento, se deve principalmente a receptores formados de subunidades α3 e α8, ao quarto e quinto dias de cultivo, respectivamente, e que o bloqueio de receptores de melatonina com luzindole inibe a resposta à acetilcolina somente ao quinto e sexto dias de desenvolvimento, provavelmente, pela inibição de outro sistema de neurotransmissão, localizado nos mesmos neurônios que contém receptores sensíveis a α-bungarotoxina em suas ramificações, como o sistema glutamatérgico. / Nicotinic acetylcholine receptors are expressed in the chick retina very early in embryonic development. The present study aimed to characterize the nicotinic acetylcholine receptors during embryonic chick retinal cell culture development and to investigate if luzindole, a melatonin receptor antagonist, is able to change the activity, distribution, and number of these receptors. The functional assays were done by microphysiometry, a method in which the increasing, agonist-stimulated, extracellular acidification rate is measured in cultured cells. The results are expressed in terms of the percentual of the acetylcholine-stimulated extracellular acidification rate over the basal extracellular acidification rate (% basal ECAR). The acetylcholine efficacy increased from the fourth to the fifth day, diminishing at the eighth culture day, and was inhibited, concentration-dependently, by dihydro-β-erythroidine (starting at 10 µM), in the retinal cells cultured for four days, and by α-bungarotoxin (10nM), in the retinal cells cultured for five and six days. The opposite did not occur. We have used [125I] α-bungarotoxin for the binding assays, and retinal cells cultured for four days presented in these assays a higher maximal-binding, smaller affinity, and higher degree of the cooperativity than retinal cells cultured for five days. Immunocytochemistry was used to characterize the development of the α3 and α8 subunits. Each of these subunits was characteristically distributed throughout the cell, independent of the age of culture. Alpha3 was mainly observed in the perikarya and proximal dendrites, whereas α8 was basically seen in processes. The distribution of the α3 and α8 immunoreactivity was not changed after chronic luzindole treatment. Also, the time of the equilibrium, the association rate, and the number of the [125I] α-bungarotoxin (10nM) binding sites were not different with or without chronic luzindole treatment in cells cultured for five days. However, the acetylcholine efficacy in the retinal cells cultured for five and six days was inhibited by luzindole, an effect that was concentration and time dependent, and that exhibited no summation with the inhibition by α-bungarotoxin. In conclusion, the acetylcholine efficacy is dependent on retinal cell culture development, and it acts mainly through neuronal nicotinic receptors comprising α3 subunits in the fourth day, and α8 subunits in the fifth day. Acetylcholine action is inhibited by melatonin receptor blockage by luzindole only at the fifth and sixth days, probably by inhibition of other receptors located in the same cells that harbor α-bungarotoxin-sensitive receptors, such as glutamate receptors.

Alzheimers disease (AD) is pathologically characterized by amyloid plaques, neurofibrillary tangles, inflammation, and neurodegeneration. According to the amyloid hypothesis of AD, the central mediating event of the disease is the deposition of amyloid. The inflammation hypothesis of AD states that it is the inflammatory response to plaques and tangles, rather than the actual lesions, which causes the disease. Studies described here combine the two approaches into a single model. Four studies are presented using a basic protocol of intrahippocampal lipopolysaccharide (LPS) injection to stimulate inflammation in transgenic mice. The first study looked at alpha7 nicotinic receptors during the glial response to Abeta deposits and LPS. Reactive astrocytes which immunolabeled for alpha7 were co-localized with Congophilic deposits in APP and APP+PS1 mice, and increased after LPS injection. Unfortunately, LPS injection into alpha7 knock out mice revealed the alpha7 labeling to be nonspecific. The second study evaluated the time course of protein and gene expression after LPS injection into nontransgenic mice. This experiment identified both a transient and chronic microglial inflammatory response, with changes in cell morphology. The third study evaluated a similar time course in APP mice. Concurrent with the inflammatory response, transient reductions in Abeta burden were seen, though compact plaque load was unaffected. The fourth and final study used dexamethasone to inhibit LPS-induced inflammation in APP mice. LPS injection reduced Abeta burden, but was completely blocked by dexamethasone co-treatment. Though dexamethasone inhibited LPS-induced CD45 and complement receptor 3 levels (markers of general microglial activation), dexamethasone had no effect on scavenger receptor A or Fc gamma receptor II/III levels. An overall hypothesis regarding LPS mediated reductions in Abeta can be proposed: It is not the presence of the LPS molecule, nor the upregulation of receptors involved in phagocytosis, but rather general glial cell activation that mediates Abeta removal. Thus, a phagocytic cell must not only bind Abeta (by various receptors) but must also be capable of engulfing the material (via general cell activation). Taken together, these studies suggest that some level of inflammation in AD is beneficial and responsible for maintaining a balance between amyloid deposition and removal.

Abstract not available

Thesis (Ph. D.)--Ohio State University, 2009. / Title from first page of PDF file. Includes bibliographical references (p. 153-165).

Nicotinic acetylcholine receptors (nAChR) are neurotransmitter-gated ion channels that exist as a family of subtypes defined by unique subunit compositions. nAChR containing α6 subunits (α6*-nAChR) have attracted interest because α6 subunits are thought to be localized in brain regions implicated in reward, mood and drug dependence. To provide new information necessary toward a more complete understanding of roles of α6*-nAChR in neuropsychiatric health and disease, three lines of investigation were pursued. A set of stably transfected, human, immortalized cell lines were generated that heterologously express nAChR α6 subunits in combination with other nAChR subunits found in reward brain regions (nAChR subunit combinations α6β2, α6β4, α6β2β3, α6β4β3, α6β2β3α5, α6β4β3α5, α6α4β2β3 and α6α4β4β3). The α6α4β2β3 combination may have a functional response to epibatidine that differs from that of the α4β2 nAChR. A unique binding site was identified in cells transfected with the α6β4β3α5 nAChR subunit combination. Messenger RNA fluorescence in situ hybridization (mRNA FISH) studies established regional and celluar distribution of nAChR α6 subunit mRNA in the mouse brain. The third line of study extended this work to examine potential co-expression of nAChR α6 subunits and glutamic acid decarboxylase (GAD) or tyrosine hydroxylase (TH) as labels of GABAergic and dopaminergic/catecholaminergic neurons respectively, using tandem mRNA FISH and fluorescence immunohistochemistry. nAChR α6 subunit signal in the substantia nigra (SN) and ventral tegmental area (VTA) was congruent with previous studies. Message was also detected in the amydala, dentate gyrus, striatum, zona incerta, and cingulate, entorhinal, perirhinal, piriform, and prelimbic cortices. nAChR α6 mRNA was coexpressed with GAD in the amygdala, dentate gyrus, striatum, SN, VTA and cingulate, entorhinal, prelimbic and prelimbic cortices. TH was exclusively co-localized with nAChR α6 mRNA in the SN and VTA. Findings suggest extended roles for α6*-nAChR in the brain, particularly in the control of GABAergic neuronal activity and/or GABA release. These studies provide new insights into the composition of α6*-nAChR, the localization and cellular origins of nAChR α6 subunit expression. Data collected suggest roles for α6*-nAChR in many brain regions, including those involved in higher order processes involved in drug dependence and reward, and in modulation of inhibitory neurotransmission.

This project utilized synthesis and in vitro assays to generate antagonist SARs at various nAChR subtypes. Alkylation of the pyridino nitrogen of the nicotine molecule afforded subtype specific antagonists at a42* nAChR subtypes and nAChR subtypes that mediate nicotine-evoked dopamine release. Using this data, a series of mono-azaaromatic quaternary salts were produced and evaluated in binding and functional assays for a42* and a7* nAChR subtypes and nAChR subtypes that mediate nicotine-evoked dopamine release. Additionally, bis-azaaromatic quaternary salts were synthesized and evaluated in the same assays. Two potent lead compounds were identified. N-n-dodecylnicotinium iodide (NDDNI) was found to be very potent at both a42* nAChR subtypes and nAChR subtypes that mediate nicotine-evoked dopamine release. And the most promising candidate was N-N-bisdodecylpicolinium dibromide (bDDPiB), which was selective for the nAChR subtypes that mediate nicotine-evoked dopamine release (IC50 = 9 nM). Additionally, using the data from the SARs, predictive computer models were generated to assist in future compound assessment without in vitro assays. Three self-organizing map (SOMs) models were generated from three different sets of compounds. The groups consisted of the mono-substituted compounds, the bissubstituted compounds, and both sets combined. The models were able to successfully "bin" the test set of compounds after developing a model from a similar set of training compounds. Additionally, using genetic functional activity (GFA) algorithms an evolutionary approach to generating predictive model equations was applied to the compounds. Three separate equations were generated in order to form a predictive method for evaluating affinities at the a4b2* receptor subtype. In addition to the modeling and SAR work of the quaternary ammonium compounds, novel synthetic methods were also employed to develop enantiomerically pure nicotine analogs. Efficient enantioselective syntheses of (S)- and R-(+)-nornicotine, (S)-and R-(+)-anabasine, and (S)-and R-(+)-anatabine have been developed, affording isomers in high enantiomeric excess.

M5 muscarinic receptors are associated with dopamine neurons of the ventral tegmental area (VTA) and substantia nigra, and provide an important excitatory input to the mesolimbic dopamine system. Here, I studied locomotion induced by systemic morphine (3, 10, 30 mg/kg, i.p.) in M5 knockout mice of the C57Bl/6 (B6) and CD1 x 129SvJ (129) background strains. M5 knockout mice of both strains showed reduced locomotion in response to 30 mg/kg morphine, while only B6 M5 knockout mice showed reduced locomotion in response to 10 mg/kg morphine. In B6 wild-type mice VTA pre-treatment with the non subtype-selective muscarinic receptor antagonist atropine (3 mg per side), but not the non subtype-selective nicotinic receptor antagonist mecamylamine (5 mg per side), reduced locomotion in response to 30 mg/kg (i.p.) morphine to a similar extent as systemic M5 knockout, suggesting that the reduced morphine-induced locomotion in M5 knockout mice was due to the loss of M5 receptors on VTA dopamine neurons. By contrast, in M5 knockout mice, either intra-VTA atropine or mecamylamine alone increased locomotion by almost 3 times relative to saline, and potentiated morphine-induced locomotion. Therefore, in M5 knockout mice, more clearly than in wild-type mice, blockade of either VTA muscarinic or nicotinic receptors activated locomotion. Infusions of morphine (50 ng) into the VTA increased nucleus accumbens dopamine efflux in urethane-anesthetized wild-type mice. Either M5 knockout or pre-treatment with VTA scopolamine (50 ug) in wild-type mice blocked accumbal dopamine efflux in response to VTA morphine. Therefore, M5 receptors are critical for excitation of dopamine neurons by intra-VTA morphine, suggesting that the reduced locomotion produced by systemic morphine in M5 knockout mice was, in part, due to loss of M5-mediated excitation of VTA dopamine neurons by opiates. The locomotion data also show that in the absence of M5 receptors, cholinergic afferents to mesolimbic dopamine neurons are inhibitory. This supports and extends the conclusions from many studies that non-M5 muscarinic receptors inhibit, and M5 receptors excite, dopamine neurons. Loss of M5-mediated excitation results in reduced acute effects of opiates.

M5 muscarinic receptors are associated with dopamine neurons of the ventral tegmental area (VTA) and substantia nigra, and provide an important excitatory input to the mesolimbic dopamine system. Here, I studied locomotion induced by systemic morphine (3, 10, 30 mg/kg, i.p.) in M5 knockout mice of the C57Bl/6 (B6) and CD1 x 129SvJ (129) background strains. M5 knockout mice of both strains showed reduced locomotion in response to 30 mg/kg morphine, while only B6 M5 knockout mice showed reduced locomotion in response to 10 mg/kg morphine. In B6 wild-type mice VTA pre-treatment with the non subtype-selective muscarinic receptor antagonist atropine (3 mg per side), but not the non subtype-selective nicotinic receptor antagonist mecamylamine (5 mg per side), reduced locomotion in response to 30 mg/kg (i.p.) morphine to a similar extent as systemic M5 knockout, suggesting that the reduced morphine-induced locomotion in M5 knockout mice was due to the loss of M5 receptors on VTA dopamine neurons. By contrast, in M5 knockout mice, either intra-VTA atropine or mecamylamine alone increased locomotion by almost 3 times relative to saline, and potentiated morphine-induced locomotion. Therefore, in M5 knockout mice, more clearly than in wild-type mice, blockade of either VTA muscarinic or nicotinic receptors activated locomotion. Infusions of morphine (50 ng) into the VTA increased nucleus accumbens dopamine efflux in urethane-anesthetized wild-type mice. Either M5 knockout or pre-treatment with VTA scopolamine (50 ug) in wild-type mice blocked accumbal dopamine efflux in response to VTA morphine. Therefore, M5 receptors are critical for excitation of dopamine neurons by intra-VTA morphine, suggesting that the reduced locomotion produced by systemic morphine in M5 knockout mice was, in part, due to loss of M5-mediated excitation of VTA dopamine neurons by opiates. The locomotion data also show that in the absence of M5 receptors, cholinergic afferents to mesolimbic dopamine neurons are inhibitory. This supports and extends the conclusions from many studies that non-M5 muscarinic receptors inhibit, and M5 receptors excite, dopamine neurons. Loss of M5-mediated excitation results in reduced acute effects of opiates.

Chiral aromatic nitrogen heterocycles are finding many applications in asymmetric organic synthesis, particularly as ligands in the preparation of chiral metal complexes. Since camphor-based chiral auxiliaries are known to be especially effective, a number of pyridines fused to the camphor skeleton have been reported. It is well known that nicotinic acid and its derivatives exhibiting qualitatively the biological activity of nicotinamide, which acts as an electron acceptor in many biological redox reactions. In connection to our works, we attempted to develop short and convenient way to prepare various camphorderived chiral pyridine or nicotinic acid derivatives. Here we report our results obtained from the annulation of (+)-&amp / #946 / -hydroxymethylenecamphor as the feasible chiral pool with various enamines derived from active methylene compounds. (+)-&amp / #946 / -Hydroxymethylenecamphor prepared from cheap and easily available natural (+)-camphor and enamines were transformed into chiral camphor-based pyridine derivatives via tandem condensation reaction in good yields.

Thesis (Ph.D.)--Virginia Commonwealth University, 2008. / Prepared for: Dept. of Pharmacology & Toxicology. Title from title-page of electronic thesis. Bibliography: leaves 187-206.