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Muscle fatigue is ubiquitous in every day life.Muscle fatigue might be considered as an altered state of motor behaviour, which impairs motor performance. By contrast, muscle fatigue could also be considered a positive phenomenon, which protects muscle tissue from damage that might be incurred to it by overuse. The principal aim of the thesis was to explore some of the mechanisms of muscle fatigue at the spinal level in animal models.The activation of multiple motor units of a single calf muscle may influence contractile properties of its neighbouring, otherwise inactive units, providing evidence for spatial spreading of fatigue between different muscle parts. The release of metabolites, their action on inactive muscle units and the effects of local hypoxia are the most likely causes. Fatigue-induced metabolite shift in the interstitium provokes excitation and/or sensitisation of high-threshold afferent fibers, with complex effects on the spinal premotoneuronal network involved in the modulation of motoneuronal output. This was examined by studing the intrasegmental lamellar distribution of the lumbar spinal interneurons following fatiguing contractions of the triceps surae muscle. Furthermore, fatigue of calf muscles enhanced the activity of fusimotor neurons to these muscles irrespective of the regime of muscle activity (isometric vs. lengthening) in conditions that simulate locomotion. Altered fusimotor activity, through increased or maintained muscle spindle afferent responsiveness may be advantageous, providing support to the skeletomotor activity and enhanced information about muscle periphery to higher nervous centres. The particular effects of interneuronal network at motor input (presynaptic inhibition system) and output (recurrent inhibition system) stages were then addressed. Fatigue of triceps surae muscle induced a suppression of the monosynaptic reflex. The intensity of presynaptic inhibition increased, while the intensity of recurrent inhibition decreased. Post fatigue-evoked changes in monosynaptic reflexes and presynaptic inhibition indicate the possibility that high-threshold afferents inhibit group Ia terminals pre-synaptically, which would allow fatigue-induced signals from the muscle to reduce the relevance of proprioceptive feedback. Besides intrasegmental, intersegmental spreading of nociceptive signals was explored. Activation of sensory afferents from dorsal neck muscles by capsaicin induces powerful activation of interneurons located in the cervical spinal cord, as well as a widespread activation of cells in lumbar spinal cord segments. The results confirm the pivotal role of small diameter muscle afferents in the orchestration of segmental responses to fatigue and show complex interactions that may lead to limited accuracy of motor output. They also depict processes that may be related to, and even become precursors of chronic muscle pain.

Rhodnius prolixus, the principal Chagas disease vector, requires a blood meal to complete its moult cycle into the next stage. Allatotropins (ATs), a family of peptides first isolated from Manduca sexta, have been shown to regulate the biosynthesis of juvenile hormone, an insect growth and development hormone; however, ATs, being multimodal peptides, also exhibit myotropic effects on some insect visceral muscles. Here, this AT family of peptides has been examined in R. prolixus. Genomic analysis revealed a cDNA fragment of 973bp encoding one mature amidated AT tridecapeptide (Rhopr-AT) with high transcript levels observed, via RT-PCR, in the central nervous system (CNS) and pool of fat body and trachea. AT-like immunoreactive neurons were found throughout the CNS and AT-like immunoreactive processes were present on some peripheral tissues. Bioassays using hindgut and dorsal vessel contraction, however, failed to demonstrate any effect of Rhopr-AT on these tissues. Future work will examine the effects of Rhopr-AT on JH production.

Rhodnius prolixus, the principal Chagas disease vector, requires a blood meal to complete its moult cycle into the next stage. Allatotropins (ATs), a family of peptides first isolated from Manduca sexta, have been shown to regulate the biosynthesis of juvenile hormone, an insect growth and development hormone; however, ATs, being multimodal peptides, also exhibit myotropic effects on some insect visceral muscles. Here, this AT family of peptides has been examined in R. prolixus. Genomic analysis revealed a cDNA fragment of 973bp encoding one mature amidated AT tridecapeptide (Rhopr-AT) with high transcript levels observed, via RT-PCR, in the central nervous system (CNS) and pool of fat body and trachea. AT-like immunoreactive neurons were found throughout the CNS and AT-like immunoreactive processes were present on some peripheral tissues. Bioassays using hindgut and dorsal vessel contraction, however, failed to demonstrate any effect of Rhopr-AT on these tissues. Future work will examine the effects of Rhopr-AT on JH production.

This study compared whether activation of muscle ergoreceptor afferents caused by isometric muscle contraction, activation of baroreceptor afferents induced by i.v. infusion of phenylephrine, or baroreceptor afferent inactivation, caused by carotid artery occlusion, elicit similar patterns of c-Fos induction in brainstem areas. Adult cats were anesthetized with α-chloralose, and in each case, the experimental intervention caused an increase in the arterial blood pressure. There were two sets of control experiments: in both, animals underwent the same surgical procedures but then either remained at rest for the entire study, or the tibial nerve was stimulated, as in the contraction group, following muscle paralysis with tubocurarine. Following the procedures, animals rested for 90 min to allow neuronal expression of c-Fos. Control cats showed very little c-Fos immunoreactivity (c-Fos-ir) in the brainstem. Muscle contraction induced c-Fos-ir expression mainly in the nucleus tractus solitarius, lateral reticular nucleus, lateral tegmental field, vestibular nucleus, subretrofacial nucleus, spinal trigeminal tract and in a lateral region of the periaqueductal grey (P 0.5-1.0). The majority of the c-Fos-ir was found in brainstem areas contralateral to the contracted muscle. In addition, muscle contraction induced c-Fos-ir in the dorsal horns of spinal segments L6-S1 on the ipsilateral side of the spinal cord. Phenylephrine infusion caused c-Fos-ir expression in the nucleus tractus solitarius, spinal trigeminal tract, solitary tract, and dorsal motor nucleus of the vagus. No c-Fos-ir was apparent in the periaqueductal grey. Carotid occlusions induced c-Fos-ir expression in the area postrema, nucleus tractus solitarius, solitary tract, and spinal trigeminal tract. Expression was bilateral. Areas that exhibited c-Fos-ir correspond to sites previously reported to release various neuropeptides in response to muscle contraction or carotid occlusions. These results indicate that the exercise pressor reflex and baroreflex activate similar, but not completely identical, sites in the brainstem.

No description available.

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2018-09-24T15:13:44Z No. of bitstreams: 1 2017 - Enely Maris da Silveira Firmiano.pdf: 12307016 bytes, checksum: d58bee7e5ddc0113fa072ab4e9aabc29 (MD5) / Made available in DSpace on 2018-09-24T15:13:44Z (GMT). No. of bitstreams: 1 2017 - Enely Maris da Silveira Firmiano.pdf: 12307016 bytes, checksum: d58bee7e5ddc0113fa072ab4e9aabc29 (MD5) Previous issue date: 2017-08-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Cap. I The aim of the current study is to investigate the histological and histochemical description, as well as the presence and immunohistochemical distribution of cytoskeleton proteins such as alpha smooth muscle actin, desmin and vimentin in the ovaries, testes and epididymis of Enyalius bilineatus, Enyalius perditus and Urostrophus vautieri. These species are representatives of family Leiosauridae, in order to help developing a database on the reproductive biology of these lizards, which could be compared to that of other reptile species and vertebrates. The herein studied specimens are deposited in the Herpetological Collection of Federal University of Juiz de Fora. The animals? ovaries, epididymis and testes were removed and sent to the Histology and Embryology Laboratory (UFRRJ), where they were fixed, processed and then subjected to histological, histochemical and immunohistochemical techniques. The ovaries of these leiosauridae are functionally-active paired organs filled with ovarian follicles at different follicular development stages. These organs are covered by a simple cubic epithelium, which presents an underlying connective tissue layer called tunica albuginea. The testes are covered by the tunica albuginea and hold septa forming lobes where the seminiferous tubules are located in. The epididymis of these lizards are convolute ducts internally coated by an epithelium, whose shape ranges from simple cylindrical to simple cubic with stereocilia. The immunohistochemical analysis applied to the ovaries of the herein studied lizards showed moderate to strong reaction to the alpha smooth muscle actin in the teak layer and in endothelial cells of blood vessels. With respect to the species? testes, this cytoskeleton protein showed strong reaction in the tunica albuginea, interstitial tissue, and in endothelial cells of blood vessels. As for the epididymis, the alpha-actin showed immunohistochemical reaction in the capsule and in the interstitial tissue of the lizards. The antibody ?desmin? showed strong immunostaining in the albuginea and ovarian stroma of E. perditus, only; however, the endothelial cells in the blood vessels of the three herein analyzed species showed positive reaction to this intermediate filament. Desmin showed immunoreactivity in the testicular albuginea and in the endothelial cells of the blood vessels in the herein analyzed leiosauridae testes; however, only E. bilineatus showed immunostaining in the interstitial region. Desmin showed positive immunoreaction in the epididymis of E. perditus and E. bilineatus, only. Vimentin did not show immunostaining in the ovaries, testes and epididymis of the three analyzed lizards. The consistent results found in the current study provide additional data on the reproductive biology of the investigated species. These data may be used for phylogenetic and behavioral comparisons between the herein studied species and other species belonging to family Leiosauridae or other reptiles Cap. II The aim of the current study is to investigate the histological description, as well as the presence and immunohistochemical distribution of alpha smooth muscle actin, desmin and vimentin in the testes and epididymis of Enyalius bilineatus, Enyalius perditus and Urostrophus vautieri, which are representatives of family Leiosauridae, in order to help developing a database on the reproductive biology of these lizards, which could be compared to that of other reptile species and vertebrates. The herein studied specimens are deposited in the Herpetological Collection of Federal University of Juiz de Fora. The animals? epididymis and testes were removed and sent to the Histology and Embryology Laboratory (UFRRJ), where they were fixed, processed and then subjected to histological and immunohistochemical techniques. The shape of the testes varies reasonably among the studied leiosauridae. These organs are covered by the tunica albuginea and hold septa forming lobes, where the seminiferous tubules are located in. The epididymis of these lizards are convolute ducts internally coated by an epithelium, whose shape ranges from simple cylindrical to simple cubic with stereocilia. The immunohistochemical analysis applied to the testes of the herein studied lizards showed strong positive reaction to the alpha smooth muscle actin in the tunica albuginea, interstitial tissue, and in endothelial cells of blood vessels. Desmin showed strong immunoreactivity in the testicular albuginea of E. bilineatus and moderate immunoreactivity in E. perditus and U. vautieri; however, only E. bilineatus showed immunostaining in the interstitial tissue region. The endothelial cells of blood vessels showed positive immunoreaction to desmin in the three herein analyzed species. The epididymis showed moderate immunohistochemical reaction to alpha smooth muscle actin in the capsule and in the interstitial tissue, whereas desmin showed positive immunoreaction in the epididymis of E. perditus and E. bilineatus, only. Vimentin did not show immunostaining in the testes and epididymis of the three analyzed lizards. The consistent results found in the current study provide additional data on the reproductive biology of the investigated species. These data may be used for phylogenetic and behavioral comparisons between the herein studied species and other species belonging to family Leiosauridae or other reptiles. / Cap. I Este trabalho investiga, al?m da descri??o histol?gica e histoqu?mica, a presen?a e distribui??o imuno-histoqu?mica de alfa-actina de m?sculo liso, desmina e vimentina nos ov?rios, test?culos e epid?dimos de Enyalius bilineatus, Enyalius perditus e Urostrophus vautieri, representantes da fam?lia Leiosauridae, para ajudar a formar uma base de dados sobre a biologia reprodutiva destes lagartos que possam ser comparados com outras esp?cies de r?pteis, bem como com outros vertebrados. Os esp?cimes estudados encontram-se depositados na Cole??o Herpetol?gica da UFJF. Os ov?rios, epid?dimos e test?culos dos animais foram removidos e encaminhados ao Laborat?rio de Histologia e Embriologia (UFRRJ), onde foram fixados, processados e ent?o submetidos ?s t?cnicas histol?gicas, histoqu?micas e imuno-histoqu?micas. Os ov?rios destes leiosaur?deos s?o ?rg?os pareados, repletos de fol?culos ovarianos, em distintos est?gios de desenvolvimento folicular. Estes s?o revestidos por epit?lio c?bico simples, com uma camada de tecido conjuntivo subjacente, a t?nica albug?nea. Os test?culos encontram-se envolvidos pela t?nica albug?nea e em seu interior cont?m septos que formam l?bulos, nos quais se localizam os t?bulos semin?feros. Os epid?dimos destes lagartos s?o ductos convolutos, revestidos internamente por um epit?lio que varia de cil?ndrico simples a c?bico simples com estereoc?lios. A imuno-histoqu?mica, nos ov?rios dos lagartos estudados, mostra uma rea??o moderada a acentuada para alfa-actina de m?sculo liso na camada da teca e em c?lulas endoteliais dos vasos sangu?neos, enquanto nos test?culos destas esp?cies nota-se uma acentuada rea??o para esta prote?na do citoesqueleto, na t?nica albug?nea, no tecido intersticial e nas c?lulas endoteliais dos vasos sangu?neos. Nos epid?dimos observa-se imunomarca??o para alfa-actina na c?psula e no tecido intersticial destes lagartos. Quanto ao anticorpo desmina, apenas em E. perditus, foi poss?vel imunorrea??o na albug?nea e no estroma ovariano, no entanto, nas tr?s esp?cies analisadas, as c?lulas endoteliais dos vasos sangu?neos demonstraram rea??o positiva a este filamento intermedi?rio. Nos test?culos dos leiosaur?deos estudados, a desmina foi imunolocalizada na albug?nea testicular e nas c?lulas endoteliais dos vasos sangu?neos, entretanto, apenas em E. bilineatus ocorreu imunomarca??o, na regi?o do interst?cio. Nos epid?dimos, a desmina demonstrou imunorrea??o positiva apenas em E. perditus e E. bilineatus. N?o houve rea??o imuno-histoqu?mica para vimentina nos ov?rios, test?culos e epid?dimos dos tr?s lagartos analisados. Este estudo obteve resultados consistentes, fornecendo assim mais dados sobre a biologia reprodutiva das esp?cies aqui investigadas, que poder?o ser utilizados para compara??es filogen?ticas e comportamentais com outras esp?cies da fam?lia Leiosauridae e outros r?pteis. Cap. II Este trabalho investiga, al?m da descri??o histol?gica, a presen?a e distribui??o imuno-histoqu?mica de alfa-actina de m?sculo liso, desmina e vimentina nos test?culos e epid?dimos de Enyalius bilineatus, Enyalius perditus e Urostrophus vautieri, representantes da fam?lia Leiosauridae, para ajudar a formar uma base de dados sobre a biologia reprodutiva destes lagartos que possam ser comparados com outras esp?cies de r?pteis, bem como com outros vertebrados. Os esp?cimes estudados encontram-se depositados na Cole??o Herpetol?gica da Universidade Federal de Juiz de Fora. Os epid?dimos e test?culos dos animais foram removidos e encaminhados ao Laborat?rio de Histologia e Embriologia (UFRRJ), onde foram fixados, processados e ent?o submetidos ?s t?cnicas histol?gicas e imuno-histoqu?micas. O formato dos test?culos varia razoavelmente entre os leiosaur?deos estudados. Estes ?rg?os encontram-se envoltos pela t?nica albug?nea e no seu interior cont?m septos que formam l?bulos incompletos, nos quais se localizam os t?bulos semin?feros. Os epid?dimos destes lagartos s?o ductos convolutos. Estes ductos s?o revestidos internamente por um epit?lio que varia de cil?ndrico simples a c?bico simples com estereoc?lios. A imuno-histoqu?mica revela uma acentuada rea??o positiva para alfa-actina de m?sculo liso nos test?culos dos leiosaur?deos analisados, na t?nica albug?nea e no tecido intersticial, assim como, nas c?lulas endoteliais dos vasos sangu?neos. A desmina apresentou acentuada imunorreatividade na albug?nea testicular em E. bilineatus e moderada em E. perditus e U. vautieri, entretanto, na regi?o do tecido intersticial, apenas em E. bilineatus ocorreu imunomarca??o. Nas tr?s esp?cies analisadas, as c?lulas endoteliais dos vasos sangu?neos demostraram imunorrea??o positiva para desmina. Nos epid?dimos observou-se rea??o imuno-histoqu?mica moderada para alfa-actina de m?sculo liso na c?psula e no tecido intersticial, enquanto a desmina demonstrou imunorrea??o positiva apenas em E. perditus e E. bilineatus. N?o houve imunomarca??o para vimentina nos test?culos e epid?dimos dos tr?s lagartos analisados. Este estudo obteve resultados consistentes, fornecendo assim mais dados sobre a biologia reprodutiva das esp?cies aqui investigadas, que poder?o ser utilizados para compara??es filogen?ticas e comportamentais com outras esp?cies da fam?lia Leiosauridae e outros r?pteis.