Fêmeas Wistar foram alimentadas durante o período gestacional e a primeira metade da lactação (10 primeiros dias de lactação) com dieta normoprotéica (19 g proteína / Kg dieta) (grupo NP) e dieta restrita em proteínas (5 g proteína / Kg dieta) (grupo LP). Paralelamente a este esquema de alimentação, elas também receberam, diariamente, por gavagem, o óleo de peixe (Fo, rico em ácido graxo poliinsaturado- AGPi n-3). Os filhotes foram subdivididos em 4 grandes grupos: NP, NP-Fo, LP e LP-Fo, sendo acompanhados até os 6 meses de idade, data na qual ocorreu a eutanásia. No momento do sacrifício, o coração foi removido e devidamente preparado para a análise em microscopia de luz e estereologia. A partir do terceiro mês, os animais do grupo LP (ambos os gêneros) exibiram um aumento na pressão arterial sistólica (hipertensão moderada), mantendo esse comportamento até o final do experimento (6 meses de idade). No entanto, a suplementação materna com o Fo foi capaz de minimizar os efeitos da desnutrição sobre a pressão arterial. Não houve diferença significante no índice corporal entre os grupos de mães suplementadas com o Fo. O ventrículo esquerdo do grupo LP (ambos os sexos) demonstrou maior espessura quando comparado ao grupo NP (+25% nos machos, P=0,01, +22% nas fêmeas, P=0,001); entretanto, o grupo LP-Fo manifestou menor espessura quando comparado com o grupo LP (-23% nos machos, P=0,001, -12% nas fêmeas, P=0,02). Os machos do grupo LP apresentaram significativamente menor vascularização intramiocárdica quando correlacionado ao grupo NP (-50%, P=0,01), enquanto os machos do grupo LP-Fo exibiram um incremento de 89% na microcirculação, quando comparados ao grupo LP (P=0,004). Ambos os gêneros do grupo LP manifestaram maior quantidade de fibrose intersticial quando comparados ao grupo NP. Vale ressaltar que a suplementação materna de Fo foi benéfica apenas no grupo LP. Sendo assim, nossos dados sugerem claramente que a suplementação materna com Fo, durante o período perinatal, é capaz de prevenir o remodelamento cardíaco adverso e a hipertensão provocados pela restrição protéica materna in útero e na lactação, tornando-se assim uma opção não farmacológica viável para a prevenção e/ou redução dos danos ocasionados pela programação em humanos. / Female Wistar rats fed in gestation and first 10 lactation days with normal protein diet (19 g protein/kg diet) (NP group) or low-protein diet (5g protein/kg diet) (LP group), also received daily fish oil supplement (Fo, n-3 PUFA rich) during same period. Offspring put in groups NP, NP-Fo, LP, LP-Fo, until sacrifice at 6-mo-old when hearts removed, prepared for light microscopy and stereology. There was mild hypertension in both LP genders from 3- until 6 mo-old. Blood pressure affected by undernutrition was minimized by maternal Fo supplementation. In body index between groups there was no significant difference with maternal Fo supplementation. The left ventricle was thicker in both genders of LP groups compared to counterpart NP groups (+25% in male LP group, P=0.01, +22% in female LP group, P=0.001); however, less thick in LP-Fo groups compared to LP groups (-23% in male LP-Fo group, P=0.001, - 12% in female LP-Fo group, P=0.02). Male LP group offspring had significantly smaller intramyocardial microcirculation than NP group (-50%, P=0.01), while male LP-Fo group had 89% higher microcirculation than LP group (P=0.004). Both gender LP group offspring had significantly higher interstitial fibrosis compared with NP groups. The maternal Fo supplementation has beneficial effects in LP , but not in NP offspring. In conclusion, our data clearly indicate postnatal hypertension and collateral cardiovascular adverse remodeling, programmed by low-protein diet in utero and lactation was prevented by perinatal supplementation with fish oil, n-3 PUFA rich, providing a viable non-pharmacologic option for preventing and/or reducing adverse programming outcomes in human.

Fêmeas Wistar foram alimentadas durante o período gestacional e a primeira metade da lactação (10 primeiros dias de lactação) com dieta normoprotéica (19 g proteína / Kg dieta) (grupo NP) e dieta restrita em proteínas (5 g proteína / Kg dieta) (grupo LP). Paralelamente a este esquema de alimentação, elas também receberam, diariamente, por gavagem, o óleo de peixe (Fo, rico em ácido graxo poliinsaturado- AGPi n-3). Os filhotes foram subdivididos em 4 grandes grupos: NP, NP-Fo, LP e LP-Fo, sendo acompanhados até os 6 meses de idade, data na qual ocorreu a eutanásia. No momento do sacrifício, o coração foi removido e devidamente preparado para a análise em microscopia de luz e estereologia. A partir do terceiro mês, os animais do grupo LP (ambos os gêneros) exibiram um aumento na pressão arterial sistólica (hipertensão moderada), mantendo esse comportamento até o final do experimento (6 meses de idade). No entanto, a suplementação materna com o Fo foi capaz de minimizar os efeitos da desnutrição sobre a pressão arterial. Não houve diferença significante no índice corporal entre os grupos de mães suplementadas com o Fo. O ventrículo esquerdo do grupo LP (ambos os sexos) demonstrou maior espessura quando comparado ao grupo NP (+25% nos machos, P=0,01, +22% nas fêmeas, P=0,001); entretanto, o grupo LP-Fo manifestou menor espessura quando comparado com o grupo LP (-23% nos machos, P=0,001, -12% nas fêmeas, P=0,02). Os machos do grupo LP apresentaram significativamente menor vascularização intramiocárdica quando correlacionado ao grupo NP (-50%, P=0,01), enquanto os machos do grupo LP-Fo exibiram um incremento de 89% na microcirculação, quando comparados ao grupo LP (P=0,004). Ambos os gêneros do grupo LP manifestaram maior quantidade de fibrose intersticial quando comparados ao grupo NP. Vale ressaltar que a suplementação materna de Fo foi benéfica apenas no grupo LP. Sendo assim, nossos dados sugerem claramente que a suplementação materna com Fo, durante o período perinatal, é capaz de prevenir o remodelamento cardíaco adverso e a hipertensão provocados pela restrição protéica materna in útero e na lactação, tornando-se assim uma opção não farmacológica viável para a prevenção e/ou redução dos danos ocasionados pela programação em humanos. / Female Wistar rats fed in gestation and first 10 lactation days with normal protein diet (19 g protein/kg diet) (NP group) or low-protein diet (5g protein/kg diet) (LP group), also received daily fish oil supplement (Fo, n-3 PUFA rich) during same period. Offspring put in groups NP, NP-Fo, LP, LP-Fo, until sacrifice at 6-mo-old when hearts removed, prepared for light microscopy and stereology. There was mild hypertension in both LP genders from 3- until 6 mo-old. Blood pressure affected by undernutrition was minimized by maternal Fo supplementation. In body index between groups there was no significant difference with maternal Fo supplementation. The left ventricle was thicker in both genders of LP groups compared to counterpart NP groups (+25% in male LP group, P=0.01, +22% in female LP group, P=0.001); however, less thick in LP-Fo groups compared to LP groups (-23% in male LP-Fo group, P=0.001, - 12% in female LP-Fo group, P=0.02). Male LP group offspring had significantly smaller intramyocardial microcirculation than NP group (-50%, P=0.01), while male LP-Fo group had 89% higher microcirculation than LP group (P=0.004). Both gender LP group offspring had significantly higher interstitial fibrosis compared with NP groups. The maternal Fo supplementation has beneficial effects in LP , but not in NP offspring. In conclusion, our data clearly indicate postnatal hypertension and collateral cardiovascular adverse remodeling, programmed by low-protein diet in utero and lactation was prevented by perinatal supplementation with fish oil, n-3 PUFA rich, providing a viable non-pharmacologic option for preventing and/or reducing adverse programming outcomes in human.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Lippia alba (Mill.) N.E. Brown (VERBENACEAE), popularly know as Erva Cidreira Brasileira, has been one of the most commonly herbs used in the Brazilian folk medicine to blood pressure control. This study aimed to investigate the cardiovascular effects of the essential oil of Lippia alba (EOLA) in rats. For the hemodynamic measurement, normotensive male Wistar rats had their abdominal aorta and lower vena cava cannulated. Initially, five chemotypes (geranial, limonene, linalool, mircene, and carvone) were tested in normotensive conscious rats. They were intravenously and in bolus administrated at the doses of 5, 10, 20, 40 and 60 mg/kg. The EOLAG showed the best results on blood pressure, being chosen for the following experiments. The administration of EOLAG (5, 10, 20, and 40 mg/kg, i.v.) induced transient hypotension and bradycardia. These responses were attenuated by atropine (2 mg/kg, i.v.), hexamethonium (20 mg/kg, i.v.) and NG-nitro-Larginine methyl ester hydrochloride (L-NAME - 20 mg/kg, i.v.), but not by indomethacin (5 mg/kg, i.v.). For in vitro approach, the rats were euthanized and the superior mesenteric artery was removed and cut in rings (1-2 mm), which were placed in organ baths containing Tyrode`s solution at 37o C and gassed with carbogen. In intact rings of rat mesenteric artery pre-contracted with phenilephrine (1 μM), EOLAG (1 - 1000 mg/mL) induced relaxation (pD2 = 1.89 ± 0.21; Emax = 110.8 ± 10.8 %) which was not modified after the removal of the endothelium (pD2 = 2.37 ± 0.16; Emax = 134.8 ± 16.5 %), after incubation with TEA (pD2 = 2.23 ± 0.04; Emax = 117.2 ± 4.96 %) or KCl (80 mM) (pD2 = 1.96 ± 0.06; Emax = 112.6 ± 6.70 %). In addition, the EOLAG was able to inhibit the contraction caused by CaCl2 and produced additional effect (34.82 %; n = 5) on maximal relaxation of nifedipine (10 μM). In conclusions, the results demonstrate that the EOLAG induces hypotensive effect, that seems to be caused by muscarinic activation and NO release, and bradycardia, that seems to be due to an activation of ganglion nicotinic and cardiac muscarinic receptors. Furthermore, EOLAG produces vasorelaxation primarily caused by blocking Ca2+ influx through voltage-operated Ca2+ channels. / A Lippia alba (Mill.) N.E. Brown (VERBENACEAE), conhecida popularmente como Erva Cidreira Brasileira, é uma das plantas mais utilizadas na medicina popular brasileira, inclusive para o tratamento da hipertensão arterial. Este estudo buscou investigar os efeitos cardiovasculares do óleo essencial de Lippia alba (OELA) em ratos. Para registro dos parâmetros hemodinâmicos, ratos machos Wistar saudáveis foram canulados na aorta abdominal e na veia cava inferior. Inicialmente foram testados 5 quimiotipos deste óleo (geranial, limoneno, linalol, mirceno e carvona), administrados por via intravenosa e in bolus, nas doses de 5, 10, 20, 40 e 60 mg/kg. Após análise destes resultados, observou-se que o quimiotipo geranial (OELAG) foi o que apresentou o melhor efeito sobre a pressão arterial, tornando-se o quimiotipo de escolha. Em animais saudáveis e não-anestesiados, o OELAG (5, 10, 20 e 40 mg/kg, i.v.) induziu hipotensão e bradicardia transientes. Estes efeitos foram atenuados em animais pré-tratados com atropina (2 mg/kg, i.v.), hexametônio (20 mg/kg, i.v.) ou LNAME (20 mg/kg, i.v.), mas não com indometacina (5 mg/kg, i.v.). Para os experimentos in vitro, os ratos foram eutanasiados e a artéria mesentérica superior foi removida e seccionada em anéis (1-2 mm), os quais foram montados em cubas para órgão isolado contendo solução de Tyrode a 37o C e gaseificada com carbogênio. Em anéis intactos de artéria mesentérica superior de ratos, pré-contraídos com fenilefrina (10 μM), o OELAG (1 - 1000 mg/mL) induziu relaxamento (pD2 = 1,89 ± 0,21; Emax = 110,8 ± 10,8 %) cujo efeito não foi alterado após remoção do endotélio (pD2 = 2,37 ± 0,16; Emax = 134,8 ± 16,5 %), após a incubação com tetraetilamônio (TEA) (pD2 = 2,23 ± 0,04; Emax = 117,2 ± 4,96 %) ou KCl (80 mM) (pD2 = 1,96 ± 0,06; Emax = 112,6 ± 6,70 %). Além disso, o OELAG foi capaz de inibir as contrações induzidas por CaCl2 e produzir um efeito adicional (34,82 %; n = 5) sobre o relaxamento máximo causado pela nifedipina (10 μM) em anéis sem endotélio. Diante destes resultados, pode-se concluir que o OELAG produz efeito hipotensor, que parece ser causado por ativação de receptores muscarínicos e liberação de NO, e bradicardia, que parece ser causado pela ativação de receptores muscarínicos cardíacos e Efeitos cardiovasculares do óleo essencial de Lippia alba em ratos MAYNARD, L.G (2011) 9 nicotínicos ganglionares. Além disso, o OELAG induz vasorelaxamento que parece ser causado inicialmente por um bloqueio do influxo de Ca2+ através dos canais de Ca2+ operados por voltagem.

No description available.

En février, 2009 un rapport de PHRMA (Pharmaceutical Research and Manufacturers of America) confirmait que plus de 300 médicaments pour le traitement des maladies cardiaques étaient en phase d’essais cliniques ou en révision par les agences règlementaires. Malgré cette abondance de nouvelles thérapies cardiovasculaires, le nombre de nouveaux médicaments approuvés chaque année (toutes indications confondues) est en déclin avec seulement 17 et 24 nouveaux médicaments approuvés en 2007 et 2008, respectivement. Seulement 1 médicament sur 5000 sera approuvé après 10 à 15 ans de développement au coût moyen de 800 millions $. De nombreuses initiatives ont été lancées par les agences règlementaires afin d’augmenter le taux de succès lors du développement des nouveaux médicaments mais les résultats tardent. Cette stagnation est attribuée au manque d’efficacité du nouveau médicament dans bien des cas mais les évaluations d’innocuité remportent la palme des causes d’arrêt de développement. Primum non nocere, la maxime d’Hippocrate, père de la médecine, demeure d’actualité en développement préclinique et clinique des médicaments. Environ 3% des médicaments approuvés au cours des 20 dernières années ont, par la suite, été retirés du marché suite à l’identification d’effets adverses. Les effets adverses cardiovasculaires représentent la plus fréquente cause d’arrêt de développement ou de retrait de médicament (27%) suivi par les effets sur le système nerveux. Après avoir défini le contexte des évaluations de pharmacologie de sécurité et l’utilisation des bio-marqueurs, nous avons validé des modèles d’évaluation de l’innocuité des nouveaux médicaments sur les systèmes cardiovasculaires, respiratoires et nerveux. Évoluant parmi les contraintes et les défis des programmes de développements des médicaments, nous avons évalué l’efficacité et l’innocuité de l’oxytocine (OT), un peptide endogène à des fins thérapeutiques. L’OT, une hormone historiquement associée à la reproduction, a démontré la capacité d’induire la différentiation in vitro de lignées cellulaires (P19) mais aussi de cellules souches embryonnaires en cardiomyocytes battants. Ces observations nous ont amené à considérer l’utilisation de l’OT dans le traitement de l’infarctus du myocarde. Afin d’arriver à cet objectif ultime, nous avons d’abord évalué la pharmacocinétique de l’OT dans un modèle de rat anesthésié. Ces études ont mis en évidence des caractéristiques uniques de l’OT dont une courte demi-vie et un profil pharmacocinétique non-linéaire en relation avec la dose administrée. Ensuite, nous avons évalué les effets cardiovasculaires de l’OT sur des animaux sains de différentes espèces. En recherche préclinique, l’utilisation de plusieurs espèces ainsi que de différents états (conscients et anesthésiés) est reconnue comme étant une des meilleures approches afin d’accroître la valeur prédictive des résultats obtenus chez les animaux à la réponse chez l’humain. Des modèles de rats anesthésiés et éveillés, de chiens anesthésiés et éveillés et de singes éveillés avec suivi cardiovasculaire par télémétrie ont été utilisés. L’OT s’est avéré être un agent ayant d’importants effets hémodynamiques présentant une réponse variable selon l’état (anesthésié ou éveillé), la dose, le mode d’administration (bolus ou infusion) et l’espèce utilisée. Ces études nous ont permis d’établir les doses et régimes de traitement n’ayant pas d’effets cardiovasculaires adverses et pouvant être utilisées dans le cadre des études d’efficacité subséquentes. Un modèle porcin d’infarctus du myocarde avec reperfusion a été utilisé afin d’évaluer les effets de l’OT dans le traitement de l’infarctus du myocarde. Dans le cadre d’un projet pilote, l’infusion continue d’OT initiée immédiatement au moment de la reperfusion coronarienne a induit des effets cardiovasculaires adverses chez tous les animaux traités incluant une réduction de la fraction de raccourcissement ventriculaire gauche et une aggravation de la cardiomyopathie dilatée suite à l’infarctus. Considérant ces observations, l’approche thérapeutique fût révisée afin d’éviter le traitement pendant la période d’inflammation aigüe considérée maximale autour du 3ième jour suite à l’ischémie. Lorsqu’initié 8 jours après l’ischémie myocardique, l’infusion d’OT a engendré des effets adverses chez les animaux ayant des niveaux endogènes d’OT élevés. Par ailleurs, aucun effet adverse (amélioration non-significative) ne fût observé chez les animaux ayant un faible niveau endogène d’OT. Chez les animaux du groupe placebo, une tendance à observer une meilleure récupération chez ceux ayant des niveaux endogènes initiaux élevés fût notée. Bien que la taille de la zone ischémique à risque soit comparable à celle rencontrée chez les patients atteints d’infarctus, l’utilisation d’animaux juvéniles et l’absence de maladies coronariennes sont des limitations importantes du modèle porcin utilisé. Le potentiel de l’OT pour le traitement de l’infarctus du myocarde demeure mais nos résultats suggèrent qu’une administration systémique à titre de thérapie de remplacement de l’OT devrait être considérée en fonction du niveau endogène. De plus amples évaluations de la sécurité du traitement avec l’OT dans des modèles animaux d’infarctus du myocarde seront nécessaires avant de considérer l’utilisation d’OT dans une population de patients atteint d’un infarctus du myocarde. En contre partie, les niveaux endogènes d’OT pourraient posséder une valeur pronostique et des études cliniques à cet égard pourraient être d’intérêt. / In february 2009, a report from PHRMA (Pharmaceutical Research and Manufacturers of America) confirmed that more than 300 drugs for treatment of cardiovascular diseases were in clinical trials or under review by regulatory agencies. Despite the abundance of new cardiovascular therapies, the number of new drugs approved each year (all indications combined) is declining steadily with only 17 and 24 new drugs approved in 2007 and 2008, respectively. Only 1 drug out of 5000 candidates will be approved after 10 to 15 years of development with an average cost of $800 millions. Several initiatives have been launched by regulatory agencies to increase the success rate in drug development but results are still awaited. This stagnation is attributed to the lack of efficacy of several drug candidates but safety assessments are the leading cause of drug development discontinuation. Primum non nocere, the maxim from Hippocrate, father of medicine, remains of major relevance in preclinical and clinical drug development. Over the past 20 years, approximately 3% of approved drugs were subsequently withdrawn from the market due to adverse effects. Cardiovascular adverse effects represent the most frequent cause of drug development discontinuation or withdrawal (27%) followed by effects on the nervous system. After defining the context of safety pharmacology evaluations and the use of biomarkers in drug development, we validated safety pharmacology models to investigate drug-induced cardiovascular, respiratory and neurological effects. As we progressed within constraints and challenges of drug development, we evaluated the efficacy and safety of oxytocin, an endogenous peptide with therapeutic potential. Oxytocin (OT), a hormone historically associated with reproduction, demonstrated the ability to induce in vitro differentiation of cell lines (P19) but also embryonic stem cells into beating cardiomyocytes. These observations lead us to consider the use of OT as a treatment for myocardial infarct. To achieve this ultimate goal, we first evaluated the pharmacokinetic of OT in an anesthetized rat model. These investigations highlighted the unique characteristics of OT including a very short half-life and a non-linear pharmacokinetic profile in response to the dose. Cardiovascular effects of OT in healthy animals were then evaluated in various species. In preclinical research, the use of various animal species and state of consciousness (conscious or anesthetized) is recognized as one of the best strategies to increase the predictive value of results obtained in animals to the human response. Our initial investigations of OT treatment regimens used various animal models including conscious and anesthetized rats, anesthetized pigs, conscious dogs with indirect blood pressure monitoring and diuresis and conscious monkeys with cardiovascular telemetry monitoring. These studies confirmed OT to have significant hemodynamic effects with variable responses depending on the state of consciousness (conscious or anesthetized), the dose, the administration protocol (bolus or infusion) and the species that were used. These screening studies enabled selection of a treatment regimen and dose without adverse effects that could subsequently be tested in efficacy studies. A porcine myocardial infarct (MI) model with reperfusion was used to evaluate the effects of OT following myocardial ischemia. In a pilot project, continuous infusion of OT initiated immediately at coronary reperfusion induced cardiovascular adverse effects in all treated animals including a reduction of left ventricular fraction shortening and worsening of dilated cardiomyopathy which is typical following MI. Considering these observations, the therapeutic strategy was revised to avoid OT treatment during the inflammatory phase which was considered maximal around day 3 post-ischemia. When initiated 8 days after MI, OT infusion induced adverse effects in animals with elevated endogenous levels of OT. In contrast, no significant effects (not statistically significant improvement) were observed in animals with low endogenous OT baseline. In placebo treated animals, a trend to observe a better recovery was noted in animals with high endogenous OT baseline. While the size of the ischemic zone was comparable to human patients with MI, the use of juvenile animals and the absence of coronary disease are important limitations of the porcine model. The potential of OT for treatment of MI remains but our results suggest that systemic administration of OT by continuous infusion as part of a replacement therapy should be investigated further in relation to endogenous levels. Further investigations on safety of the treatment with OT on animal MI models are warranted before the use of OT can be considered in the patient population after myocardial infarct. On the other hand, endogenous levels of OT may have a prognostic value and clinical trials to investigate this hypothesis may be of interest.

En février, 2009 un rapport de PHRMA (Pharmaceutical Research and Manufacturers of America) confirmait que plus de 300 médicaments pour le traitement des maladies cardiaques étaient en phase d’essais cliniques ou en révision par les agences règlementaires. Malgré cette abondance de nouvelles thérapies cardiovasculaires, le nombre de nouveaux médicaments approuvés chaque année (toutes indications confondues) est en déclin avec seulement 17 et 24 nouveaux médicaments approuvés en 2007 et 2008, respectivement. Seulement 1 médicament sur 5000 sera approuvé après 10 à 15 ans de développement au coût moyen de 800 millions $. De nombreuses initiatives ont été lancées par les agences règlementaires afin d’augmenter le taux de succès lors du développement des nouveaux médicaments mais les résultats tardent. Cette stagnation est attribuée au manque d’efficacité du nouveau médicament dans bien des cas mais les évaluations d’innocuité remportent la palme des causes d’arrêt de développement. Primum non nocere, la maxime d’Hippocrate, père de la médecine, demeure d’actualité en développement préclinique et clinique des médicaments. Environ 3% des médicaments approuvés au cours des 20 dernières années ont, par la suite, été retirés du marché suite à l’identification d’effets adverses. Les effets adverses cardiovasculaires représentent la plus fréquente cause d’arrêt de développement ou de retrait de médicament (27%) suivi par les effets sur le système nerveux. Après avoir défini le contexte des évaluations de pharmacologie de sécurité et l’utilisation des bio-marqueurs, nous avons validé des modèles d’évaluation de l’innocuité des nouveaux médicaments sur les systèmes cardiovasculaires, respiratoires et nerveux. Évoluant parmi les contraintes et les défis des programmes de développements des médicaments, nous avons évalué l’efficacité et l’innocuité de l’oxytocine (OT), un peptide endogène à des fins thérapeutiques. L’OT, une hormone historiquement associée à la reproduction, a démontré la capacité d’induire la différentiation in vitro de lignées cellulaires (P19) mais aussi de cellules souches embryonnaires en cardiomyocytes battants. Ces observations nous ont amené à considérer l’utilisation de l’OT dans le traitement de l’infarctus du myocarde. Afin d’arriver à cet objectif ultime, nous avons d’abord évalué la pharmacocinétique de l’OT dans un modèle de rat anesthésié. Ces études ont mis en évidence des caractéristiques uniques de l’OT dont une courte demi-vie et un profil pharmacocinétique non-linéaire en relation avec la dose administrée. Ensuite, nous avons évalué les effets cardiovasculaires de l’OT sur des animaux sains de différentes espèces. En recherche préclinique, l’utilisation de plusieurs espèces ainsi que de différents états (conscients et anesthésiés) est reconnue comme étant une des meilleures approches afin d’accroître la valeur prédictive des résultats obtenus chez les animaux à la réponse chez l’humain. Des modèles de rats anesthésiés et éveillés, de chiens anesthésiés et éveillés et de singes éveillés avec suivi cardiovasculaire par télémétrie ont été utilisés. L’OT s’est avéré être un agent ayant d’importants effets hémodynamiques présentant une réponse variable selon l’état (anesthésié ou éveillé), la dose, le mode d’administration (bolus ou infusion) et l’espèce utilisée. Ces études nous ont permis d’établir les doses et régimes de traitement n’ayant pas d’effets cardiovasculaires adverses et pouvant être utilisées dans le cadre des études d’efficacité subséquentes. Un modèle porcin d’infarctus du myocarde avec reperfusion a été utilisé afin d’évaluer les effets de l’OT dans le traitement de l’infarctus du myocarde. Dans le cadre d’un projet pilote, l’infusion continue d’OT initiée immédiatement au moment de la reperfusion coronarienne a induit des effets cardiovasculaires adverses chez tous les animaux traités incluant une réduction de la fraction de raccourcissement ventriculaire gauche et une aggravation de la cardiomyopathie dilatée suite à l’infarctus. Considérant ces observations, l’approche thérapeutique fût révisée afin d’éviter le traitement pendant la période d’inflammation aigüe considérée maximale autour du 3ième jour suite à l’ischémie. Lorsqu’initié 8 jours après l’ischémie myocardique, l’infusion d’OT a engendré des effets adverses chez les animaux ayant des niveaux endogènes d’OT élevés. Par ailleurs, aucun effet adverse (amélioration non-significative) ne fût observé chez les animaux ayant un faible niveau endogène d’OT. Chez les animaux du groupe placebo, une tendance à observer une meilleure récupération chez ceux ayant des niveaux endogènes initiaux élevés fût notée. Bien que la taille de la zone ischémique à risque soit comparable à celle rencontrée chez les patients atteints d’infarctus, l’utilisation d’animaux juvéniles et l’absence de maladies coronariennes sont des limitations importantes du modèle porcin utilisé. Le potentiel de l’OT pour le traitement de l’infarctus du myocarde demeure mais nos résultats suggèrent qu’une administration systémique à titre de thérapie de remplacement de l’OT devrait être considérée en fonction du niveau endogène. De plus amples évaluations de la sécurité du traitement avec l’OT dans des modèles animaux d’infarctus du myocarde seront nécessaires avant de considérer l’utilisation d’OT dans une population de patients atteint d’un infarctus du myocarde. En contre partie, les niveaux endogènes d’OT pourraient posséder une valeur pronostique et des études cliniques à cet égard pourraient être d’intérêt. / In february 2009, a report from PHRMA (Pharmaceutical Research and Manufacturers of America) confirmed that more than 300 drugs for treatment of cardiovascular diseases were in clinical trials or under review by regulatory agencies. Despite the abundance of new cardiovascular therapies, the number of new drugs approved each year (all indications combined) is declining steadily with only 17 and 24 new drugs approved in 2007 and 2008, respectively. Only 1 drug out of 5000 candidates will be approved after 10 to 15 years of development with an average cost of $800 millions. Several initiatives have been launched by regulatory agencies to increase the success rate in drug development but results are still awaited. This stagnation is attributed to the lack of efficacy of several drug candidates but safety assessments are the leading cause of drug development discontinuation. Primum non nocere, the maxim from Hippocrate, father of medicine, remains of major relevance in preclinical and clinical drug development. Over the past 20 years, approximately 3% of approved drugs were subsequently withdrawn from the market due to adverse effects. Cardiovascular adverse effects represent the most frequent cause of drug development discontinuation or withdrawal (27%) followed by effects on the nervous system. After defining the context of safety pharmacology evaluations and the use of biomarkers in drug development, we validated safety pharmacology models to investigate drug-induced cardiovascular, respiratory and neurological effects. As we progressed within constraints and challenges of drug development, we evaluated the efficacy and safety of oxytocin, an endogenous peptide with therapeutic potential. Oxytocin (OT), a hormone historically associated with reproduction, demonstrated the ability to induce in vitro differentiation of cell lines (P19) but also embryonic stem cells into beating cardiomyocytes. These observations lead us to consider the use of OT as a treatment for myocardial infarct. To achieve this ultimate goal, we first evaluated the pharmacokinetic of OT in an anesthetized rat model. These investigations highlighted the unique characteristics of OT including a very short half-life and a non-linear pharmacokinetic profile in response to the dose. Cardiovascular effects of OT in healthy animals were then evaluated in various species. In preclinical research, the use of various animal species and state of consciousness (conscious or anesthetized) is recognized as one of the best strategies to increase the predictive value of results obtained in animals to the human response. Our initial investigations of OT treatment regimens used various animal models including conscious and anesthetized rats, anesthetized pigs, conscious dogs with indirect blood pressure monitoring and diuresis and conscious monkeys with cardiovascular telemetry monitoring. These studies confirmed OT to have significant hemodynamic effects with variable responses depending on the state of consciousness (conscious or anesthetized), the dose, the administration protocol (bolus or infusion) and the species that were used. These screening studies enabled selection of a treatment regimen and dose without adverse effects that could subsequently be tested in efficacy studies. A porcine myocardial infarct (MI) model with reperfusion was used to evaluate the effects of OT following myocardial ischemia. In a pilot project, continuous infusion of OT initiated immediately at coronary reperfusion induced cardiovascular adverse effects in all treated animals including a reduction of left ventricular fraction shortening and worsening of dilated cardiomyopathy which is typical following MI. Considering these observations, the therapeutic strategy was revised to avoid OT treatment during the inflammatory phase which was considered maximal around day 3 post-ischemia. When initiated 8 days after MI, OT infusion induced adverse effects in animals with elevated endogenous levels of OT. In contrast, no significant effects (not statistically significant improvement) were observed in animals with low endogenous OT baseline. In placebo treated animals, a trend to observe a better recovery was noted in animals with high endogenous OT baseline. While the size of the ischemic zone was comparable to human patients with MI, the use of juvenile animals and the absence of coronary disease are important limitations of the porcine model. The potential of OT for treatment of MI remains but our results suggest that systemic administration of OT by continuous infusion as part of a replacement therapy should be investigated further in relation to endogenous levels. Further investigations on safety of the treatment with OT on animal MI models are warranted before the use of OT can be considered in the patient population after myocardial infarct. On the other hand, endogenous levels of OT may have a prognostic value and clinical trials to investigate this hypothesis may be of interest.