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| Author(s): |
Alberto Fernando Oliveira Justo
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas |
| Defense date: | 0000-00-00 |
| Examining board members: |
Gilberto De Nucci;
Maria Andréia Delbin;
Fernando Silva Carneiro;
Jamaira Aparecida Victorio;
Andre Sampaio Pupo
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| Advisor: | Gilberto De Nucci |
| Abstract | |
Comparative physiology studies are fundamental for understanding evolutionary relationships between species, such as physiological processes and functions of different species, adaptations, evolutionary gains and losses. Previously, our group have showed that, in isolated ring from aorta of evolutionarily the ancient species Chelonoidis carbonaria (jabuti-piranga) and Pantherophis guttatus (corn snake), the aortae contraction induced by electrical field stimulation (EFS) is mediated by catecholamines released by the endothelium without the influence of adrenergic nerves, unlike the classical mechanism seen in the vascular system of mammals, in which, when adrenergic nerves are inhibited, there is a reduction or a abolishment of the vessel contractile response. This study aimed to i) explore the mechanism involved in EFS evoked contraction of aortae isolated from the venomous snakes Crotalus durissus terrificus (rattlesnake) and Bothrops jararaca (jararaca); ii) compare these results with those obtained in more ancient reptile species as jabuti-piranga and corn snake, and iii) investigate the role of endothelium in EFS-induced aortae contraction. Additionally, as our group has been also studying the endothelium-derivated catecholamine release in some mammals, we evaluated of endothelial catecholamine production in human endothelium of a paraganglioma biopsy. Aortac rings isolated by rattlesnakes and jararacas were contracted by the EFS in a frequency-dependent manner (4, 8 and 16 Hz), in the presence and absence of sympatholytic agents (phentolamine and guanethidine) and the voltage-gated sodium channel blocker tetrodotoxin (TTX), as well as in aortae with intact or removed endothelium. Immunohistochemistry analysis were performed in the aorta of these species and in the human endothelium in order to investigate the expression of tyrosine hydroxylase (TH), an enzyme essential in the detection of catecholamines, and protein S100, a neural marker. The EFS-evoked contractions of rattlesnake and jararaca aortae were frequency-but also endothelium-dependent once the rings contractions were reduced in the absence of endothelium. When incubated with guanethidine and phentolamine, the contractions were reduced or abolished, however, in the presence of TTX, there was no significant difference in aortae contraction. Immunohistochemistry analyses has revealed that the expression of TH was exclusive to the endothelium of the snake's aorta and the S100 protein expression was not observed. Likewise, the endothelium of human paraganglioma tissue only expressed TH, while neoplastic cells expressed both TH and S100 in neoplastic cells. Our results suggest that, the contraction stimulated by EFS in aortic rings from rattlesnake and jararaca, is mediated by release of catecholamine from the without involvement of sympathetic nerves. We also demonstrate the expression of TH in the human endothelium, suggesting a catecholamine synthesis function in this tissue (AU) | |
| FAPESP's process: | 15/15583-7 - Pharmacological, eletrophysiological and morphological characterization of novel tetrodotoxin-resistant sodium channel coupled to corpus cavernosum of snakes |
| Grantee: | Alberto Fernando Oliveira Justo |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |