Navegando por Palavras-chave "alpha(1)-adrenoceptor"

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    alpha(1)-adrenoceptors trigger the snake venom production cycle in secretory cells by activating phosphatidylinositol 4,5-bisphosphate hydrolysis and ERK signaling pathway
    (Elsevier B.V., 2008-08-01) Kerchove, Celine Marie de; Luna, Milene Schmidt do Amaral e; Zablith, Mariana Bayerlein; Lazari, Maria de Fatima Magalhaes [UNIFESP]; Smaili, Soraya Soubhi [UNIFESP]; Yamanouye, Norma; Inst Butantan; Universidade Federal de São Paulo (UNIFESP)
    Loss of venom from the venom gland after biting or manual extraction leads to morphological changes in venom secreting cells and the start of a cycle of production of new venom. We have previously shown that stimulation of both (alpha- and beta-adrenoceptors in the secretory cells of the venom gland is essential for the onset of the venom production cycle in Bothrops jararaca. We investigated the signaling pathway by which the alpha(1)-adrenoceptor initiates the venom production cycle. Our results show that the alpha(1)-adrenoceptor subtype is present in venom gland of the snake. in quiescent cells, stimulation of alpha(1)-adrenoceptor with phenylephrine increased the total inositol phosphate concentration, and this effect was blocked by the phospholipase C inhibitor U73122. Phenylephrine mobilized Ca(2+) from thapsigargin-sensitive stores and increased protein kinase C activity. in addition, alpha(1)-adrenoceptor stimulation increased the activity of ERK 1/2, partially via protein kinase C. Using RTPCR approach we obtained a partial sequence of a snake alpha(1)-adrenoceptor (260 bp) with higher identity with alpha(1)- and alpha(1B)-adrenoceptor from different species. These results suggest that alpha(1)-adrenoceptor in the venom secreting cells are probably coupled to a G(q) protein and trigger the venom production cycle by activating the phosphatidylinositol 4,5-bisphosphate and ERK signaling pathway. (c) 2008 Elsevier Inc. All rights reserved.
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    Cloning, expression and immunolocalization of alpha(1)-adrenoceptor in different tissues from rhesus monkey and human male reproductive tract
    (Oxford Univ Press, 2008-02-01) Patrão, Marilia Tavares Coutinho da Costa [UNIFESP]; Queiroz, Daniel Barboza Cava [UNIFESP]; Grossman, Gail; Petrusz, Peter; Lazari, Maria de Fatima Magalhaes [UNIFESP]; Avellar, Maria Christina Werneck [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Univ N Carolina
    This study reports the genomic organization of the rhesus alpha(1A)-adrenoceptor gene (ADRA1A). Full-length cloning of rhesus ADRA1A splice variants was achieved by combining PCR screening of a seminal vesicle cDNA library and 5'-RACE assays with total RNA from seminal vesicle. the classical ADRA1A mRNA (ADRA1A_nu 1) and six full-length ADRA1A splice variants were identified representing transcripts that code for functional (ADRA1A_nu 1, ADRA1A_nu 2a, ADRA1A_nu 3a, ADRA1A_nu 3d, ADRA1A_nu 3e) and truncated (ADRA1A_nu 2c and ADRA1A_nu 3c) receptor isoforms. Comparative analysis of the deduced amino acid sequence indicated that rhesus ADRA1A_i1 isoform (corresponding to the ADRA1A_nu 1 transcript) shares high identity to the amino acid sequence present in the classical alpha(1A)-adrenoceptor from human and other mammalian species. Partial nucleotide sequences for rhesus alpha(1B)-(ADRA1B) and alpha(1D)-adrenoceptor (ADRA1D) transcripts were also characterized. RT-PCR studies indicated differential distribution of all ADRA1A-related splice variants as well as ADRA1B and ADRA1D mRNAs, in tissues from rhesus and human male reproductive tract. Immunohistochemistry revealed alpha(1A)-adrenoceptor (ADRA1A_ i1) immunostaining in smooth muscle cells and epithelial cells of rhesus efferent ductules, epididymis and seminal vesicle. Taken together the present results demonstrate that the complexity of the splicing mechanisms involved in the regulation of the ADRA1A gene is not restricted to human and is a common characteristic among Old World monkeys.
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    Effects of androgen manipulation on alpha(1)-adrenoceptor subtypes in the rat seminal vesicle
    (Elsevier B.V., 2004-08-06) Mendes, F. R.; Hamamura, M.; Queiroz, DBC; Porto, C. S.; Avellar, MCW; Universidade Federal de São Paulo (UNIFESP)
    This study analyses possible changes during surgical and chemical castration in the expression and pharmacological characteristics of alpha(1)-adrenoceptor in adult rat seminal vesicle. Ribonuclease protection assays indicated that alpha(1a)- was the predominant mRNA, while alpha(1b)- and alpha(1d)-adrenoceptor transcripts were detected in lower abundance in this tissue. alpha(1a)-adrenoceptor mRNA expression presented a complex dependency on androgens, while alpha(1b)- and alpha(1d)-adrenoceptor transcripts were both upregulated with surgical and chemical castration, suggesting a negative modulation by androgens. Testosterone treatment reversed the effects caused by surgical castration. Functional studies confirmed the involvement of alpha(1A)- and alpha(1B)-adrenoceptor in the seminal vesicle contractile responses, and suggested that alpha(1B)-induced contractile response was upregulated after castration. Taken together, the results suggest that alpha(1)-adrenoceptor expression in seminal vesicle is differentially regulated by the androgen status of the rat. (C) 2004 Elsevier Inc. All rights reserved.