Steroid modulation of angiotensin II action in the rat anterior pituitary gland.

OBJECTIVES: The present study was designed to test whether various steroid hormones modulate differently angiotensin II (AngII) action in the anterior pituitary in males and females.

MATERIAL AND METHODS: Adult female and male rats were treated with one of the following substances: oil (control), pregnenolone sulfate (PREG-S), 17beta-estradiol benzoate (E2,) progesterone (P), or dehydroepiandrosterone sulfate (DHEA-S), given in intraperitoneal injections for five days in dose of 50 microg per animal per day. Because AngII is known to act in the anterior pituitary through the phosphatidiloinositol breakdown, thus increasing the level of inositol-1,4,5-trisphosphate (IP3), the IP3 concentration was determined 24 hours after the injection in the anterior pituitary homogenate exposed to AngII.

RESULTS: In control animals (without steroids) AngII stimulated concentration of IP(3) stronger in females than in males. E(2) and DHEA-S enhanced AngII effects in both males and females. PREG-S increased AngII-induced IP(3) concentration in females, but not males. Progesterone raised AngII effect on IP(3) concentration in males, only when high concentrations of peptide were used.

CONCLUSION: These results indicate that pituitary sensitivity to AngII stimulation is modulated by steroid hormones and is related to the gender of the animal.

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