Changes in progesterone receptor mRNA content in the rabbit lung during early pregnancy and after sex steroid hormone treatment

Abstract

In this work we determined progesterone receptor (PR) mRNA content in female rabbit lung during the first 5 days of pregnancy and in ovariectomized animals after subcutaneous injection of oestradiol benzoate (25 µg/kg) for 2 days or oestradiol benzoate (25 µg/kg) for 2 days plus a single dose of progesterone (5 mg/kg) on day three. On each day (0-5) of pregnancy and 24 h after the last dose in the case of the treated animals, animals were killed and lung was excised; total RNA was extracted and processed for Northern blot analysis. The results showed three main PR mRNA transcripts (6·1, 4·4 and 1·8 kb) in rabbit lung.The 4·4 kb species was the most abundant. PR mRNA content was markedly increased by oestradiol benzoate and downregulated by progesterone. It significantly increased on the first day of pregnancy and then diminished progressively, reaching its lowest value on day 5. These findings suggest that PR mRNA content in the rabbit lung is regulated by sex steroid hormones and changes according to the physiological concentrations of oestradiol and progesterone.

Hormones and Breathing

“…Used with permission from Zwillich et al 103 regulated by sex steroids and changes according to the physiologic concentrations of estradiol and progesterone. 111 Synthetic progestins (MPA and chlormadinone acetate) have been used for respiratory stimulation with variable success. A few studies have reported some improvement in sleepiness, blood gas levels, and in number or duration of apneic and hypopneic events.…”

Nocturnal transcutaneous carbon dioxide tension in postmenopausal estrogen users and non-users

“…Progesterone is a powerful respiratory stimulant. 7 Furthermore, since estrogen upregulates progesterone receptors, 8 one would expect profound changes in respiratory control across natural menopause. However, arterial oxygen and end-tidal carbon dioxide (EtCO 2 ) levels during wakefulness and sleep show only a slight difference before and after menopause 9 or on/off menopausal hormone therapy.…”

Expression of progesterone receptor related to the polymorphism in the PGR gene in the rabbit reproductive tract1

“…In sheep, less PR-B expression in the oviduct and uterus was related to greater embryo survival at d 4 and 7 of gestation in synchronous females compared with asynchronous females (García-Palencia et al, 2007). Besides, it is known that PR is downregulated by progesterone in the uterus of the rabbit and other mammalian species (Brenner et al, 1979(Brenner et al, , 1990Camacho-Arroyo et al, 1998;Bouchard, 1999;Ulbrich et al, 2003). Then, decreased PR expression should be associated with greater progesterone concentration.…”