Pituitary synaptic protein SNAP-25 sensitive to GnRH is necessary for LH release.
OBJECTIVE
The protein SNAP-25 is located in the plasma membrane and is known to participate in hormone exocytosis process. In the present work we studied the role of SNAP-25 on LH secretion in permeabilized adenohypophyseal cultured cells. The question of whether GnRH regulates SNAP-25 expression in adenohypophyseal cultured cells and in the adenohypophyses in vivo was also investigated.


METHODS
In digitonin-permeabilized cells incubated with anti-SNAP-25, stimulated LH secretion with Ca2+ was analysed. The presence and expression of SNAP-25 in adenohypophyseal cultured cells incubated with GnRH and in adenohypophyses of orchidectomized rats with GnRH administration was studied by immunochemistry and immunoblotting.


RESULTS
Immunochemical study revealed that SNAP-25 was present in cultured adenohypophyseal cells and in adenohypophysis of orchidectomized rats both with GnRH treatment. We found that LH secretion can be blocked by antibodies raised against SNAP-25 in permeabilized cells. Likewise, GnRH administration induced a significant decrease of SNAP-25 expression in cultured adenohypophyseal cells and in adenohypophysis of orchidectomized rats.


CONCLUSIONS
Our study showed that SNAP-25 is present in adenohypophyses in vitro as well as in vivo and that is involved in LH release and that GnRH can modify its expression.
Quintanar
J Luis
JL
Laboratory of Neurophysiology, Department of Physiology and Pharmacology, Centro de Ciencias Básicas, Universidad Autónoma de Aguascalientes, Aguascalientes, México. jlquinta@correo.uaa.mx
Salinas
Eva
E
Chávez-Morales
Rosa María
RM
Quintanar-Stephano
Andrés
A
D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007150:Immunohistochemistry; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000502:physiology*; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D050825:Synaptosomal-Associated Protein 25
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone