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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

Methcathinone Analogue Activity at the Human Serotonin Transporter

Varn, William Drake 01 January 2016 (has links)
In the last few years, there has been continued concern about synthetic drug abuse in both the United States and worldwide. Small adjustments in drug compound structure often allow synthetic drug makers to manufacture a legal product that can produce the same highs as illegal counterparts. Unfortunately, this is happening faster than the government can outlaw the drug compounds, and a wide variety of synthetics are now appearing on the street. This study evaluated the effects on the human serotonin transporter of six different 4-para substituted methcathinone compounds. Using a Xenopus oocyte model, the efficacy of each MCAT analogue at hSERT was calculated by applying the Hill equation to the oocyte data. This study suggests that volume, size, and steric bulk of the compound may generally influence efficacy at hSERT in a direct manner, but that other factors, like lipophilicity, may also play an important role in potency at the transporter.
482

Synthesis and Biological Evaluation of Rigid Analogues of Methamphetamines

Forsyth, Andrea N 18 May 2012 (has links)
A series of rigid azetidenyl-based methamphetamine analogs were synthesized from commercially available N-Boc-azetidinone. The benzylideneazetidine analogs were prepared via a Wittig olefination via the ylides generated from the corresponding triphenylphosphonium benzylhalide salts. The substituted benzylazetidine analogs were synthesized from the corresponding benzylideneazetidienes via hydrogention over palladium and platinum catalysts. The benzylideneazetidine and benzyliazetidine analogs were evaluated at monoamine transporters as a part of preliminary structure-activity study for the development of novel monoamine transporter ligands. The binding affinities of the azetidine analogs were determined at dopamine (DAT) and serotonin (SERT) transporters in rat brain tissue preparations. The preliminary in vitro binding studies revealed that the rigid scaffold of the azetidine ring system was an effective substitution for the 2-aminopropyl group of methamphetamine and led to compounds with nanomolar binding affinity at dopamine and serotonin. In general, the benzylideneazetidine analogs were more potent than the corresponding benzylazetidine analogs. In addition, the azetidine analogs were more selective for the serotonin transporter than the dopamine transporter. The 3-(3,4-dichlorobenzylidene)azetidine (24m) was the most potent analog of the series with Ki values of 139 nM for SERT and 531 nM for DAT (DAT/SERT = 3.8).
483

Synthesis and Biological Evaluation of N-heterocycles for Activity on Monoamine Transporters and Exploration of Iridium Chemistry for Synthesis of Medicinally Important Molecules

Apsunde, Tushar D. 13 August 2014 (has links)
The focus of these studies was directed towards the synthesis of novel N-heterocyclic compounds and pharmacological evaluation of these compounds for activity at monoamine transporters. A series of novel piperidine and pyrrolidine analogues were prepared from commercially available starting material with a three and four step synthetic method, respectively. A variety of substituents on the aromatic ring were incorporated to achieve a diverse library of compounds. The preliminary binding studies of piperidine molecules showed strong affinity towards serotonin transporters and moderate affinity towards dopamine transporters. The focus of further studies was directed towards utilization of iridium catalysis for the development of new synthetic methods for biologically important molecules. This research has led to the development of a new synthetic strategy for the construction of nicotine and its analogues. In addition, the iridium catalysis was also used for alkylation of amides with primary and secondary alcohols under microwave conditions.
484

Migräne und das serotonerge System / Migraine and the serotonergic system

Herzog, Anna Laura January 2008 (has links) (PDF)
Untersuchung zu single-nucleotid-polymorphismen (SNPs) der Serotoninrezeptoren 5-HT2A, 5-HT3A, des Neurotrophins BDNF und des Enzyms Tryptophanhydroxlase auf deren Korrelation mit Migräne mit und ohne Aura. / Correlation between single nucleotide polymorphisms in genes of serotonergic 5-HT2A and 5-HT3A-receptors, brain derived neurotropic factor and Tryptophanhydroxylase with migraine with and without aura phenomenon.
485

Expressionsanalytische und behaviourale Phänotypisierung der Nos1 Knockdown Maus / Expressional and behavioural phenotyping of the Nos1 knockdown mouse

Kittel-Schneider, Sarah January 2010 (has links) (PDF)
Der gasförmige Neurotransmitter Stickstoffmonoxid (NO) spielt eine Rolle bei verschiedenen physiologischen Vorgängen, aber auch psychiatrischen Erkrankungen wie Aggression, Ängstlichkeit, Depression und auch bei kognitiven Funktionen. Um mehr über die physiologische Rolle von NO herauszufinden untersuchten wir mittels Gen-Expressionsanalyse und Verhaltensversuchen Mäuse, bei denen die neuronale Isoform der Stickstoffmonoxidsynthase ausgeschaltet wurde. Die so genannte NOS-I ist die hauptsächliche Quelle von NO im zentralen Nervensystem. Knockout Tiere sind wertvolle Werkzeuge um sowohl den Einfluss eines Gens auf Verhalten als auch möglicherweise damit zusammenhängende Veränderungen des Transkriptoms zu identifizieren. Dies ist wichtig um herauszufinden, mit welchen molekularen Pfaden bestimmte Verhaltensweisen korreliert sind. In Bezug auf NOS-I gibt es zwei bisher beschriebene Knockout Mäuse Stämme. Es existieren KOex6 Knockout Mäuse, in welchen es überhaupt keine katalytisch aktive NOS-I gibt und es gibt einen Mausstamm, bei dem Exon 1 deletiert wurde, was aufgrund alternativer NOS-I Splicevarianten zu einer residualen Expression von bis zu 7% führt. Daher sind diese Mäsue besser zutreffend als Knockdown Mäuse zu bezeichnen. In der vorliegenden Arbeit untersuchten wir die Nos1 Knockdown Mäuse, da die hier vorliegende Situation wohl ähnlicher zu der bei menschlicher genetischer Varianten ist, da eine komplette Disruption bisher noch nicht beim Menschen beschrieben wurde. Es gibt diverse Studien, welche den behaviouralen Phänotyp der Nos1 Knockdown Mäuse untersuchen, aber diese widersprechen sich zum Teil. Bei unserer Untersuchung legten wir den Schwerpunkt auf Verhaltenstests, welche spezifische Symptome des Aufmerksamkeitsdefizit-/Hyperaktivitätssyndrom (ADHS) aufdecken sollten. Wir führten den Elevated Plus Maze Test (EPM) und ein modifiziertes Lochbrett-Paradigma, die COGITAT-Box, durch. Um die den gefundenen Verhaltensänderungen zugrunde liegenden molekularen Mechanismen herauszufinden, suchten wir nach Unterschieden der Expression des Serotonin- (5HTT) und des Dopamintransporters (DAT) zwischen den Knockdown und den Wildtyp Mäusen. Wir hatten spekuliert, dass die Disruption der NOS-I zu einer modifizierten Expression des DAT oder des 5HTT geführt habe könnte wegen den bekannten engen Interaktionen zwischen dem nitrinergen und den monoaminergen Systemen. Wir fanden einen diskret anxiolytischen Phänotyp, da die Knockdown Mäuse eine längere Zeit auf dem offenen Arm des EPM verbrachten bzw. häufiger den offenen Arm betraten im Vergleich zu dem Wildtypen. Dies war nicht durch eine höhere lokomotorische Aktivität zu erklären. Auch beobachteten wir ein geschlechterunabhängiges kognitives Defizit im Arbeits- und Referenzgedächtnis in der COGITAT-Box. Überraschenderweise fanden wir keine signifikante Dysregulation der Monoamin-Transporter in der Expressionsanalyse mittels der quantitativen Real Time PCR. Dies war eher unerwartet, da vorherige Studien verschiedene Veränderungen im serotonergen und dopaminergen System bei den Nos1 Knockdown Mäusen gefunden hatten, wie z.B. einen verminderten Serotonin-Umsatz in frontalen Cortex und hypofunktionale 5 HT1A and 5HT1B Rezeptoren. Auch ist bekannt, dass NO direkt Monoamin-Transporter nitrosyliert. Zusammenfassend zeigen die Nos1 Knockdown Mäuse ein charakteristisches behaviourales Profil mit reduzierter Ängstlichkeit und Defiziten im Gedächtnis. Weitere Studien sollten folgen um zu klären, ob diese Mäuse als Tiermodell für z.B. die Alzheimer-Erkrankung oder das Aufmerksamkeitsdefizit-/Hyperaktivitätssyndrom dienen könnten und die weitere pathophysiologische Rolle des NO bei neuropsychiatrischen Erkrankungen herauszufinden. / The gaseous messenger nitric oxide (NO) has been implicated in a wide range of behaviours, including aggression, anxiety, depression and cognitive functioning. To further elucidate the physiological role of NO and its down-stream mechanisms, we conducted behavioral and expressional phenotyping of mice lacking the neuronal isoform of nitric oxide synthase (NOS1), the major source of NO in the central nervous system. Knockout animals are valuable tools to identify both the behavioural impact of a given gene, as well as subsequent changes of the transcriptome to correlate behaviour to molecular pathways. With respect to NOS-I, two genetically modified mouse strains have been described in the literature. There are the KOex6 knockout mice in which you find a complete absence of catalytically active NOS-I and previously generated animals with a targeted deletion of exon 1 which show a residual NOS-I expression up to 7% rendering those mice actually Nos1 knockdown animals. In this study we used the knockdown animals because this situation seems to be more closely to human genetic variation, since a complete disruption of the gene has not yet been described in man. There a several studies on the behavioural phenotype of these animals but they are in part contradictory. In our investigations we had a special emphasis on ADHD-relevant tests, we performed the Elevated Plus Maze and a modified holeboard paradigm, the COGITAT Box. To further examine the underlying molecular mechanisms, we searched for differences in the expression of the serotonine and the dopamine transporter between the knockdown and the wildtype mice because we had speculated that disruption of the NOS-I might lead to a modified expression of the DAT or the 5HTT because of the tight interactions of NO and both the serotonergic as well as the dopaminergic system. A subtle anxiolytic phenotype was observed, with knockdown mice displaying a higher open arm time in the Elevated Plus Maze (student's t-test p>0.05) as compared to their respective wildtypes which was not caused by a higher locomotor acivity. Also there was gender-independent cognitive impairment in spatial learning and memory, as assessed by an automatized holeboard paradigm, the COGITAT Box. Here the working memory error and the reference memory error were in parts significantly different between knockdown animals and their respective wildtypes. Surprisingly no significant dysregulation of monoamine transporters was evidenced by qRT PCR. This we did not expect because of previous findings in Nos1 knockout mice that showed for example a reduced 5 HT turnover in the frontal cortex along with a concomitant increase in frontal 5-HT as well as 5 HT1A and 5HT1B receptor hypofunctioning and the fact that NO directly nitrosylates monoamine transporters. Taken together, Nos1 knockdown mice display a characteristic behavioural profile consisting of reduced anxiety and impaired learning and memory. Further research has to assess the value of these mice as animal models e.g. for Alzheimer’s disease or attention deficit disorder, in order to clarify a possible pathophysiological role of NO therein.
486

A double blind placebo controlled study of granisetron in antidepressant induced sexual dysfunction

Ording-Jespersen, Sean Melville January 2005 (has links)
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Medicine in the branch of Psychiatry Melbourne, 2005 / Sexual dysfunction is a common side effect of treatment with antidepressants, particularly those with a serotonergic action. The problem has significant implications for a patient’s quality of life and their compliance with medication. Given the often longterm nature of depressive disorders and their treatment this side effect poses a potential management challenge and may have serious prognostic implications. There are currently few evidence-based treatment strategies for the management of antidepressant induced sexual dysfunction. This study was conducted to evaluate the usefulness of granisetron, a serotonin type-3 receptor antagonist, in the treatment of women experiencing sexual dysfunction due to serotonergic antidepressants. Twelve women with antidepressant induced sexual dysfunction were assigned to receive either granisetron (N=5) or placebo (N=7) in a 14-day randomised, double blind, placebo controlled drug trial. Two subjects in the granisetron group did not complete the study. Each subject’s sexual functioning was assessed at baseline, day 7 and day 14 using both the Arizona Sexual Experience Scale and the Feiger Sexual Function and Satisfaction Questionnaire. No statistical differences were measured either at baseline or at endpoint between the granisetron and placebo groups. The study did not produce evidence supporting the usefulness of granisetron as an adjunctive medication in women with antidepressant induced sexual dysfunction. Furthermore, this finding does not suggest a primary role for the serotonin type-3 receptor in the pathogenesis of this side effect.
487

Constraints versus adaptations as contending evolutionary explanations of morphological structure : The giraffe (Giraffa Camelopardalis) head and neck as a heuristic model

Badlangana, Ludo Nlambiwa 01 December 2008 (has links)
The current study uses the head and neck of giraffe (Giraffa camelopardalis) as a model for tracking the course of evolutionary change. Gould (2002) has argued that there are three main avenues of evolutionary change that result in the genesis of new morphologies. These are phylogenetic constraints, structural or allometric scaling laws of form, and specific unique adaptations. It is well known that the unique characteristic of the giraffe is its extremely long neck and yet, it only has seven cervical vertebrae. To study the neck the vertebral body lengths of different aged giraffes were measured to determine the contribution of the cervical vertebrae to the total vertebral column. The vertebrae of several extant ungulates as well as those of fossil giraffids were used as a comparison with the giraffe. CT scans were used on several giraffe skulls to study the extent of the frontal sinus in the giraffe in an attempt to explain why the giraffe evolved such a large frontal sinus. The vertebral columns and skulls of several ungulates, including the okapi (Okapia johnstoni) were also used to compare with the results obtained from the giraffe. Immunohistochemistry was used to study the medulla and spinal cord sections of the giraffe to determine if the location and size of the nuclei remained unchanged to the basic ungulate or mammalian plan in spite of the unusually long neck, or if this long neck led to changes in the nuclei found in those regions. The results of these stains were all compared to the published literature available. Although more studies need to be conducted on other ungulates to conclusively determine why giraffe have evolved a long neck, overall the results showed that the anatomy giraffe head and neck remained true to the basic mammalian plan, with very little changing in terms of it morphology. The giraffe brain and spinal cord also resembled that of a typical ungulate. This leads to the conclusion that constraints and allometric scaling laws of form play a greater role than previously thought in the evolution of extreme morphologies.
488

Efeitos do escitalopram sobre a identificação de expressões faciais / Effects of escitalopram on the processing of emotional faces.

Alves Neto, Wolme Cardoso 16 May 2008 (has links)
ALVES NETO, W.C. Efeitos do escitalopram sobre a identificação de expressões faciais. Ribeirão Preto, SP: Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo; 2008. Os inibidores seletivos da recaptura de serotonina (ISRS) têm sido utilizados com sucesso para o tratamento de diversas patologias psiquiátricas. Sua eficácia clínica é atribuída a uma potencialização da neurotransmissão serotoninérgica, mas pouco ainda é conhecido sobre os mecanismos neuropsicológicos envolvidos nesse processo. Várias evidências sugerem que a serotonina estaria envolvida, entre outras funções, na regulação do comportamento social, nos processos de aprendizagem e memória e no processamento de emoções. O reconhecimento de expressões faciais de emoções básicas representa um valioso paradigma para o estudo do processamento de emoções, pois são estímulos condensados, uniformes e de grande relevância para o funcionamento social. O objetivo do estudo foi avaliar os efeitos da administração aguda e por via oral do escitalopram, um ISRS, no reconhecimento de expressões faciais de emoções básicas. Uma dose oral de 10 mg de escitalopram foi administrada a doze voluntários saudáveis do sexo masculino, em modelo duplo-cego, controlado por placebo, em delineamento cruzado, ordem randômica, 3 horas antes de realizarem a tarefa de reconhecimento de expressões faciais, com seis emoções básicas raiva, medo, tristeza, asco, alegria e surpresa mais a expressão neutra. As faces foram digitalmente modificadas de forma a criar um gradiente de intensidade entre 10 e 100% de cada emoção, com incrementos sucessivos de 10%. Foram registrados os estados subjetivos de humor e ansiedade ao longo da tarefa e o desempenho foi avaliado pela medida de acurácia (número de acertos sobre o total de estímulos apresentados). De forma geral, o escitalopram interferiu no reconhecimento de todas as expressões faciais, à exceção de medo. Especificamente, facilitou a identificação das faces de tristeza e prejudicou o reconhecimento de alegria. Quando considerado o gênero das faces, esse efeito foi observado para as faces masculinas, enquanto que para as faces femininas o escitalopram não interferiu com o reconhecimento de tristeza e aumentou o de alegria. Além disso, aumentou o reconhecimento das faces de raiva e asco quando administrado na segunda sessão e prejudicou a identificação das faces de surpresa nas intensidades intermediárias de gradação. Também apresentou um efeito positivo global sobre o desempenho na tarefa quando administrado na segunda sessão. Os resultados sugerem uma modulação serotoninérgica sobre o reconhecimento de expressões faciais emocionais e sobre a evocação de material previamente aprendido. / ALVES NETO, W.C. Effects of escitalopram on the processing of emotional faces. Ribeirão Preto, SP: Faculty of Medicine of Ribeirão Preto, University of São Paulo; 2008. The selective serotonin reuptake inhibitors (SSRI) have been used successfully for the treatment of various psychiatry disorders. The SSRI clinical efficacy is attributed to an enhancement of the serotonergic neurotransmission, but little is known about the neuropsychological mechanisms underlying this process. Several evidences suggest that serotonin is involved with the regulation of social behavior, learning and memory process and emotional processing. The recognition of basic emotions on facial expressions represents an useful task to study the emotional processing, since they are a condensate, uniform and important stimuli for social functioning. The aim of the study was to verify the effects of the SSRI escitalopram on the recognition of facial emotional expressions. Twelve healthy males completed two experimental sessions each (crossover design), in a randomized, balanced order, double-blind design. An oral dose of 10 mg of escitalopram was administered 3 hours before they performed an emotion recognition task with six basic emotions angry, fear, sadness, disgust, happiness and surprise and neutral expression. The faces were digitally morphed between 10% and 100% of each emotional standard, creating a 10% steps gradient. The subjective mood and anxiety states through the task were recorded and the performance through the task was defined by the accuracy measure (number of correct answers divided by the total of stimuli presented). In general, except of fear, escitalopram interfered with all the emotions tested. Specifically, facilitated the recognition of sadness, while impaired the identification of happiness. When the gender of the faces was analyzed, this effect was seen in male, but not female faces, where it improves the recognition of happiness. In addition, improves the recognition of angry and disgusted faces when administered at the second session and impaired the identification of surprised faces at intermediate levels of intensity. It also showed a global positive effect on task performance when administered at the second session. The results indicate a serotonergic modulation on the recognition of emotional faces and the recall of previous learned items.
489

Sistema serotonérgico - relações com o sistema de temporização circadiano. / Serotonergic system - Interactions with the circadian timing system.

Pinato, Luciana 17 December 2007 (has links)
Componente essencial do sistema de temporização circadiano, o núcleo supraquiasmático (NSQ) possui três aferências principais: o trato retinohipotalâmico (TRH), o trato geniculohipotalâmico (TGH) e as terminações serotonérgicas da rafe. Suas células possuem oscilação circadiana autônoma que resultam na expressão rítmica dos chamados genes do relógio. O presente estudo analisa as concentrações de 5-HT nos núcleos da rafe e NSQ de ratos em livre-curso e mostra que somente os núcleos obscuro e linear apresentam ritmos endógenos com ação determinante do ciclo claro-escuro na no ritmo diário; compara a organização intrínseca do NSQ de primatas e roedores, mostrando organização diferenciada dos terminais serotonérgicos e do TGH em relação aos do TRH sugerindo funções diferentes dessas aferências no NSQ de primatas. Além disso, o padrão de expressão dos genes do relógio no NSQ do primata ao longo do período de atividade mostrou que os genes BMAL1 e Per1 apresentam pico de expressão ao redor do ZT2 e o gene Per2 no ZT7. Os dados demonstram diferenças interespecíficas importantes nas características neuroquímicas e moleculares do NSQ. / Essential component of the circadian timing system, the suprachiasmatic nucleus (SCN) receives dense retinohypothalamic RHT, geniculohypothalamic tract GHT and serotonergic innervation arriving from the raphe nuclei. SCN has pacemaker cells that produce rhythmic expression of clock genes. This study investigates the levels of 5-HT in the raphe nuclei and SCN in free running rats and shows endogenous rhythms in the obscurus and linear raphe nuclei, which is regulated by the daily light: dark cycle rhythms. The comparative analysis of the intrinsic structure of the SCN of primates and rodents shows a different organizational pattern of serotonergic and GHT terminals and the RHT terminals, suggesting different actions of serotonin and neuropeptide Y in the control of circadian rhythmicity in primates. Moreover, the pattern of the clock genes SCN expression along the awaken period in the primates show that BMAL1 and Per1 RNAm peaks of expression occur around ZT2 and Per2 around ZT7. These data suggest that the neural organization of the circadian timing system in the studied primate differ from those of the most commonly studied rodents.
490

Participação da serotonina no efeito tipo-antidepressivo induzido pela inibição da nNOS no hipocampo de ratos / Serotonin participation in the antidepressant-like effect induced by hippocampal nNOS inhibition

Sato, Vinicius Antonio Hiroaki 07 July 2011 (has links)
Introdução: O óxido nítrico (NO) tem sido relacionado como um importante neuromodulador envolvido com a neurobiologia da adaptação ao estresse e da depressão. De fato, a administração sistêmica ou intra-hipocampal de inibidores da NO sintase neuronial (nNOS) induz efeitos do tipo antidepressivo em modelos animais. Evidências recentes indicam que os efeitos sistêmicos dos inibidores da nNOS são dependentes dos níveis de serotonina no encéfalo. O sistema serotoninérgico do hipocampo dorsal, por ativação dos receptores serotoninérgicos do tipo 1A (5HT1A), facilita a adaptação ao estresse e contribui para os efeitos comportamentais de drogas antidepressivas. Portanto, o objetivo do presente estudo foi testar a hipótese de que o efeito do tipo antidepressivo induzido pela administração hipocampal de inibidores da nNOS seria mediado pela facilitação da neurotransmissão serotoninérgica local e subseqüente ativação de 5HT1A. Métodos: Após cirurgia estereotáxica, ratos Wistar com cânulas-guia direcionadas ao hipocampo dorsal foram submetidos a sessão de pré-teste (PT 15 minutos de nado) e receberam administrações locais das drogas: N-propil-L-arginina (NPA, inibidor seletivo da nNOS: 0,00001 - 1 nmol/0,5 µL), fluoxetina (SSRI: 1, 3 e 10 nmol/0,5 µL), WAY100635 (antagonista seletivo para 5HT1A: 1, 3 e 10 nmol/0,5 µL) ou veículo (0,5 µL). 24h depois, o tempo de imobilidade foi registrado em uma sessão de 5 minutos de nado. Todos os protocolos foram aprovados por um comitê de ética local (Proc. No 08.1.1133.53.4) Resultados: A administração intra hipocampal de NPA ou fluoxetina reduziu significativamente o tempo de imobilidade em animais submetidos ao teste do nado forçado, um efeito tipo antidepressivo. A administração de WAY100635 não induziu efeito por si, mas foi capaz de bloquear os efeitos induzidos por fluoxetina ou NPA. Conclusões: A inibição da nNOS, pelo NPA, ou a inibição da recaptação de serotonina, pela fluoxetina, no DH induziu efeito do tipo antidepressivo de similar magnitude. O fato de que o pré-tratamento com WAY100635 foi capaz de bloquear os efeitos induzidos por NPA e fluoxetina indica que ambos os efeitos são mediados por facilitação da neurotransmissão serotoninérgica local e subseqüente ativação de 5HT1A. Assim, esses resultados sugerem que níveis aumentados de NO no DH poderiam levar a um déficit na neurotransmissão serotoninérgica local e, portanto, predispor ao desenvolvimento das conseqüências comportamentais do estresse. / Introduction: Nitric oxide (NO) has been suggested to play an important role in the neurobiology of stress adaptation and depression. In fact, systemic or hippocampal administration of neuronal NO synthase (nNOS) inhibitors induces antidepressant-like effects in animal models. Recent evidence indicates that the systemic effects of nNOS inhibitors are dependent on serotonin levels in the brain. The serotonergic system of the dorsal hippocampus (DH), through the activation of serotonin 1A (5-HT1A) receptors, is proposed to mediate stress adaptation and the behavioral effects of antidepressant drugs. Therefore, the aim of the present study was to test the hypothesis that the antidepressant-like effects induced by nNOS inhibition into the hippocampus would be mediated by a facilitation of the local serotonergic neurotransmission and subsequent 5-HT1A receptor activation. Methods: Male Wistar rats with guide-cannulae aimed at the DH were submitted to the pretest session (PT - 15 minutes of swimming) and received local administrations of the drugs: n-propyl-L-arginine (NPA, selective nNOS inhibitor: 0.00001 - 1 nmol/0.5 µL), fluoxetine (SSRI: 1, 3 and 10 nmol/0.5 µL), WAY100635 (selective 5-HT1A antagonist: 1, 3 and 10 nmol/0.5 µL) or vehicle (0.5 µL). One day later, the immobility time was registered at a 5 minutes swimming test session. All protocols were approved by a local ethical committee (Proc. N. 08.1.1133.53.4.) Results: The intrahippocampal administration of NPA or fluoxetine reduced the immobility time in animals submitted to the forced swimming test, an antidepressant-like effect in this model. WAY100635 did not induce any effect per se, but it was able to block the effects induced by fluoxetine or NPA. Conclusions: Inhibition of nNOS, by NPA, or inhibition of serotonin reuptake, by fluoxetine, in the DH induced antidepressant-like effects of similar magnitude. The fact that pretreatment with WAY100635 was able to block NPA- and fluoxetine-induced effects indicates that both effects are mediated by a facilitation of the local serotonergic neurotransmission and subsequent activation of 5-HT1A receptors. Therefore, these results suggest that increased NO levels in the DH could impair local serotonergic neurotransmission and, thus, predisposes to the development of stress-induced behavioral consequences, such as depressive-like behaviors.

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