Effects of Pygeum africanum extract (Tadenan) on vasoactive intestinal peptide receptors, G proteins, and adenylyl cyclase in rat ventral prostate.
BACKGROUND
Tadenan (a Pygeum africanum extract) is a drug used in the treatment of benign prostatic hyperplasia. Its effects on prostate fibroblast proliferation and bladder function after partial outlet obstruction have been demonstrated in various pharmacological studies. However, its effects at the molecular level are poorly documented.


METHODS
Tadenan was dissolved in peanut oil. Rats were orally given two daily doses of the drug (1 or 10 mg/kg b.w.) for 4 days. Vasoactive intestinal peptide (VIP) binding, adenylyl cyclase stimulation, and expression of G-protein subunits were studied in rat prostatic membranes by established procedures.


RESULTS
Tadenan treatment of castrated/testosterone-replaced rats was performed in order to interfere with prostatic cell proliferation. This experimental approach resulted in increases of: 1) VIP effect on adenylyl cyclase stimulation through alpha(s) G-subunit; 2) alpha(i) activation by low Gpp[NH]p doses (in the presence of forskolin); and 3) alpha(s), alpha(i1/2), and alpha(i3/0) levels. However, there were no modifications in membranes from quiescent, nonproliferating prostates (untreated rats).


CONCLUSIONS
The observed regulatory role of Tadenan on various prostatic components of the adenylyl cyclase system, together with previous findings on protein kinase C-mediated signal transduction, open a complex array of possibilities of direct actions of this phytotherapeutic agent in the prostate.
Solano
R M
RM
Unidad de Neuroendocrinología Molecular, Departamento de Bioquímica y Biología Molecular, Universidad de Alcalá, Alcalá de Henares, Spain.
García-Fernández
M O
MO
Clemente
C
C
Querol
M
M
Bellamy
F
F
Sanchez-Chapado
M
M
Prieto
J C
JC
Carmena
M J
MJ
D000262:Adenylyl Cyclases / Q000187:drug effects* / Q000378:metabolism; D000284:Administration, Oral; D000818:Animals; D002455:Cell Division; D005233:Fatty Alcohols / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000187:drug effects* / Q000502:physiology; D006131:Growth Inhibitors / Q000494:pharmacology*; D008297:Male; D010936:Plant Extracts; D011467:Prostate / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D018005:Receptors, Vasoactive Intestinal Peptide / Q000187:drug effects* / Q000502:physiology
D005233:Fatty Alcohols; D006131:Growth Inhibitors; D010936:Plant Extracts; D018005:Receptors, Vasoactive Intestinal Peptide; C009375:Tadenan; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases