Non-genomic effects of progesterone on Rho kinase II in rat gastric smooth muscle cells

Abstract

Various studies have shown that pregnancy is associated with gastrointestinal complaints that might result from disturbance of the normal contractile pattern of smooth muscle. Progesterone is an important steroid hormone, which plays a crucial role in female pregnancy. Progesterone affects muscle cells by genomic mechanisms, through nuclear receptors, and non-genomic mechanisms, through unidentified pathways. Non-genomic actions were defined as those occurring within 10 min of progesterone exposure. The aim of the present study was to investigate the non-genomic effect of progesterone on Rho kinase II activity in gastric smooth muscle. Single smooth muscle cells of the stomach obtained from Sprague Dawley rats were used. Dispersed gastric smooth muscle cells were treated with progesterone or acetylcholine (ACh) separately. Cells designated for progesterone treatment were incubated with 1 μM progesterone for 10 min. Rho kinase II expression and both basal and ACh-induced Rho kinase II activity were measured via specifically designed enzyme-linked immunosorbent assay (ELISA) and activity assay kits respectively in both control and progesterone-treated groups. Progesterone inhibited the ACh-induced, but not the basal, Rho kinase II activity in dispersed gastric smooth muscle cells without affecting its expression level. This study suggested that progesterone can rapidly affect the contractile activity of isolated gastric smooth muscle cells in rats via inhibition of the Rho kinase II pathway.

Effect of progesterone on nitric oxide/cyclic guanosine monophosphate signaling and contraction in gastric smooth muscle cells

“…Previous study by our group has also indicated that progesterone may rapidly affect the contractile activity of stomach muscle via inhibition of the Rho kinase pathway (17). Moreover, we recently reported lower RhoA/Rho-associated protein kinase pathway activation and lower levels of MLC 20 phosphorylation in female stomach muscle cells compared with in male cells (22,23).…”

“…Cells in the treatment groups were incubated at room temperature for 10 min with progesterone (1 µM), progesterone and ODQ (GC inhibitor; 1 µM), or progesterone and L-NNA (NO synthase inhibitor; 1 µM). A progesterone concentration of 1 µM was effective in our previous research (17); in addition, after reviewing the progesterone dose response curve reported in other studies (25,26), the concentration of 1 µM occurred in the middle of the curve and was thus deemed suitable. Cells were then stimulated for 10 min with acetylcholine (ACh; 0.1 µM) in the presence or absence of treatment agents at room temperature.…”

“…The same group later reported that progesterone decreased the basal colon motility in vivo by altering the levels and actions of prostaglandins (16). Our group previously demonstrated that progesterone may rapidly affect the contractile activity of isolated gastric smooth muscle cells (GSMCs) in rats via inhibition of the Rho kinase II pathway (17). Physiologically, smooth muscle is an important component of the GI tract, and maintaining its normal contractile behavior is essential for proper GI functions.…”

Supplementation of 17β-Estradiol Normalizes Rapid Gastric Emptying by Restoring Impaired Nrf2 and nNOS Function in Obesity-Induced Diabetic Ovariectomized Mice

“…Much attention is needed to understand the effects of P4 and PR in Gp. Interestingly, P 4 has been observed to downregulate G-coupled protein receptors (GPCRs), specifically those that mediate contraction and relaxation of gastric smooth muscle cells via the Rho kinase pathway [ 27 ]. Al-Shboul further proposed that hormonal effect on muscle contraction represents mostly a non-genomic action of PR in rat gastric smooth muscle.…”

“…PR signaling is proposed to regulate G-protein expression levels in female chronic constipation studies [ 25 ]. Though the mechanisms responsible for the non-genomic effects of P 4 are not fully understood, it has been proposed that P 4 , through PR, may lead to rapid activation of tyrosine kinases and phospholipases, mitogen-activated protein kinase, or inhibition of membrane transport systems [ 26 , 27 ]. Furthermore, the types of changes induced by the non-genomic actions may be tissue specific, as diverse effects have been demonstrated in muscle, neural, endocrine, and reproductive cells.…”