In vitro and in vivo evidence for direct dopaminergic inhibition of VIP-immunoreactive pituitary cells.
In order to establish whether dopamine is involved in the regulation of immunocytochemical expression of VIP in pituitary cells, in vivo and in vitro studies were carried out on male rats after treatment with haloperidol and dopamine, respectively. In the in vivo studies, following intraventricular (third ventricle) administration of haloperidol, an increase in the total number of VIP-immunoreactive cells (p < 0.05) was observed; additionally, the cellular, cytoplasmic and nuclear areas were increased (p < 0.01). The in vitro studies demonstrated that dopamine induces a significant decrease (p < 0.05) in the total number of VIP-immunoreactive cells, which were smaller than the cells from the control dishes, because dopamine induces a significant decrease in their cellular, cytoplasmic and nuclear areas (p < 0.01). These results support the hypothesis that dopamine is a physiological inhibitor of pituitary VIP expression and suggest that dopamine modulates the auto- or paracrine effects of VIP in the rat pituitary.
Carretero
J
J
Department of Human Anatomy and Histology, Faculty of Medicine, University of Salamanca, Spain.
Sanchez
F
F
Rubio
M
M
Francos
C M
CM
Blanco
J
J
Vazquez
R
R
D000818:Animals; D002478:Cells, Cultured; D004298:Dopamine / Q000502:physiology*; D006220:Haloperidol / Q000008:administration & dosage / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D008297:Male; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014660:Vasoactive Intestinal Peptide / Q000096:biosynthesis* / Q000276:immunology
D014660:Vasoactive Intestinal Peptide; D006220:Haloperidol; D004298:Dopamine