scholarly journals Effects of Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) 27 and PACAP 38 on the Release of Luteinizing Hormone (LH) from Cultured Bovine Anterior Pituitary Cells.

1995 ◽  
Vol 41 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Shinichiro KOYAMA ◽  
Tsutomu HASHIZUME ◽  
Shinichi OHASHI ◽  
Shigeto KANEMATSU
Keyword(s):  
Luteinizing Hormone ◽  
Adenylate Cyclase ◽  
Anterior Pituitary ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Pituitary Adenylate Cyclase

scholarly journals Interactions of ovarian steroids with pituitary adenylate cyclase-activating polypeptide and GnRH in anterior pituitary cells

1999 ◽  
pp. 207-214 ◽  
Author(s):  
O Ortmann ◽  
W Asmus ◽  
K Diedrich ◽  
KD Schulz ◽  
G Emons
Keyword(s):  
Adenylate Cyclase ◽  
Adenylyl Cyclase ◽  
Anterior Pituitary ◽  
Pituitary Cells ◽  
Camp Production ◽  
Estradiol Treatment ◽  
Ovarian Steroids ◽  
Anterior Pituitary Cells ◽  
Pituitary Adenylate Cyclase ◽  
Lh Secretion

Pituitary adenylate cyclase-activating polypeptide (PACAP) releases LH and FSH from anterior pituitary cells. Although this effect is relatively weak, it has a strong sensitizing action on GnRH-induced gonadotropin secretion. Here we investigated the possibility that ovarian steroids, which are well-known modulators of LH secretion, interact with PACAP and GnRH in pituitary gonadotrophs. Rat pituitary cells were treated for 48 h with vehicle, 1 nmol/l estradiol, 1 nmol/l estradiol + 100 nmol/l progesterone or 48 h with 1 nmol/l estradiol and 4 h with 100 nmol/l progesterone. The cells were stimulated for 3 h with 1 nmol/l GnRH or 100 nmol/l PACAP. Estradiol treatment alone enhanced basal as well as GnRH- or PACAP-stimulated LH secretion. LH release was facilitated by additional short-term progesterone treatment. Long-term treatment with estradiol and progesterone led to reduced LH responses to GnRH and PACAP. Neither treatment paradigms affected cAMP production. However, estradiol treatment led to enhanced cAMP accumulation in quiescent or GnRH-stimulated cells. PACAP-induced increases of cAMP production were inhibited by estradiol treatment. After 7-h preincubation with 10 nmol/l PACAP, cells responded with enhanced LH secretion to GnRH stimulation. When steroid pretreatment was performed the responsiveness of gonadotrophs to low concentrations of GnRH was still increased. In contrast, at high concentrations of GnRH the sensitizing action of PACAP on agonist-induced LH secretion was lost in steroid-treated cells. There were no significant differences between the steroid treatment paradigms. It is concluded that estradiol but not progesterone acts as a modulator of adenylyl cyclase in gonadotrophs. The stimulatory effect of estradiol is thought to be involved in its sensitizing action on agonist-induced LH secretion. The inhibitory effect of estradiol on PACAP-stimulated adenylyl cyclase activities seems to be responsible for the loss of its action to sensitize LH secretory responses to GnRH.

Sign in / Sign up

Export Citation Format

Share Document