Effect of hypothyroidism on synaptosomal-associated protein of 25 kDa and syntaxin-1 expression in adenohypophyses of rat

Abstract

The aim of this study was to analyze the expression of SNAP-25 and syntaxin-1 in the adenohypophyses of hypothyroid rats. Rats were divided into: 1) controls; 2) thyroidectomized 40 days; and 3) thyroidectomized 40 days with replacement of T4 20 days after surgery. Adenohypophyses were studied by immunohistochemistry and immunoblot analysis using antibodies against SNAP-25, syntaxin-1 and TSH. By immunostaining, SNAP-25 and syntaxin-1 were conspicuous and were localized around cytoplasmic vacuoles of thyroidectomy cells. Immunoblot analysis shows that thyroidectomy increases adenohypophysial SNAP-25 expression and decreases syntaxin-1 levels. T4 administration for 20 days produces a recovery similar to control values. In conclusion, thyroidectomy produces changes in both expression and immunoreactivity of SNAP-25 and syntaxin-1 in adenohypophyses of rats and these effects can be reversed by T4 administration.

Dynamics of subcellular organelles, growth hormone, Rab3B, SNAP‐25, and syntaxin in rat pituitary cells caused by growth hormone releasing hormone and somatostatin

“…Salinas et al (1999), who investigated the presence of syntaxin-1 and SNAP-25 by immunohistochemistry in different parts of the mouse, guinea pig, and cat pituitary, suggested that syntaxin-1 and SNAP-25 were involved in the hormonal secretary process of the adenohypophysis as well as the neurohypophysis of these animals. Quintanar et al (2002) analyzed the expression of SNAP-25 and syntaxin-1 in the adenohypophyses of hypothyroid rats, and found that thyroidectomy produced changes in both the expression and the immunoreactivity of SNAP-25 and syntaxin-1 in the adenohypophyses of the rats and that these effects could be reversed by T4 administration.…”

“…Since previous reports have either mainly studied rab family, or have focused exclusively on the SNARE system (Jacobsson and Meister, 1996;Lledo et al, 1993;Quintanar and Salinas, 2002;Salinas et al 1999;Tahara et al, 1999;Tasaka et al, 1998), to date these proteins have not yet been investigated together. Therefore, their mutual relationships have remained unclear.…”

Identification of exocytotic membrane proteins in three rotifer species

“…To demonstrate immunoreactivity of the exocytotic membrane proteins (Syntaxin-1, Syntaxin-4, SNAP-23, and SNAP-25), the avidin-biotin peroxidase complex method (Hsu et al, 1981), using the kit (Vectastin ABC kit, Dimension Laboratories Inc., CA, USA) with slight modifications (Quintanar & Salinas, 2002). Primary antibodies raised against Syntaxin-1, Syntaxin-4, and SNAP-23 (rabbit polyclonal antiSyntaxin-1, anti-Syntaxin-4, or anti-SNAP-23, respectively.…”

“…SNAP-25 and Syntaxin-1 are located in the plasma membrane of neural, endocrine, and exocrine tissues. These proteins have been reported in glandular cells of parasitic helminthes (Quintanar & López, 2001), in frog chromaffin cells (Quintanar et al, 1998), in mast cells (Salinas et al, 2004), in the rat pituitary (Quintanar & Salinas, 2002), and in neuronal tissue of rat (Mitchell & Ryan, 2004). Nevertheless, in aquatic invertebrates there are no reports of SNAREs proteins in the literature.…”

Functional and Morphological Analyses of Rab Proteins and the Soluble N-ethylmaleimide-sensitive Factor Attachment Protein Receptor (SNARE) System in the Secretion of Pituitary Hormones

“…Salinas et al investigated the presence of syntaxin-1 and SNAP-25 using immunohistochemical methods in different parts of mouse, guinea pig and cat pituitaries, and suggested that syntaxin-1 and SNAP-25 are involved in the hormonal secretory process of both the adenohypophysis and neurohypophysis in these species [34]. Quintanar and Salinas analyzed the expression of SNAP-25 and syntaxin-1 in the adenohypophyses of hypothyroid rats, and found that thyroidectomy resulted in changes to both expression and immunoreactivity of SNAP-25 and syntaxin-1, and that these effects could be reversed by T4 administration [32]. However, the direct function of rab3B in conjunction with the secretion of pituitary hormones and SNARE system remains unclear.…”