The mechanism of honokiol-induced and magnolol-induced inhibition on muscle contraction and Ca 2+ mobilization in rat uterus

Abstract

The effects of honokiol and magnolol extracted from the Magnolia officinalis on muscular contractile responses and intracellular Ca(2+) mobilization were investigated in the non-pregnant rat uterus. Honokiol and magnolol (1-100 micromol/l) were observed to inhibit spontaneous and uterotonic agonists (carbachol, PGF(2alpha), and oxytocin)-, high K(+)-, and Ca(2+) channel activator (Bay K 8644)-induced uterine contractions in a concentration-dependent manner. The inhibition rate of honokiol on spontaneous contractions appeared to be slower than that of magnolol-induced response. The time periods that were required for honokiol and magnolol, at 100 micromol/l, to abolish 50% spontaneous contractions were approximately 6 min. Furthermore, honokiol and magnolol at 10 micromol/l also blocked the Ca(2+)-dependent oscillatory contractions. Consistently, the increases in intracellular Ca(2+) concentrations ([Ca(2+)](i)) induced by PGF(2alpha) and high K(+) were suppressed by both honokiol and magnolol at 10 micromol/l. After washout of these treatments, the rise in [Ca(2+)](i) induced by PGF(2alpha) and high K(+) was still partially abolished. In conclusion, the inhibitory effects of honokiol and magnolol on uterine contraction may be mediated by blockade of external Ca(2+) influx, leading to a decrease in [Ca(2+)](i). Honokiol and magnolol may be considered as putative Ca(2+) channel blockers and be of potential value in the treatment of gynecological dysfunctions associated with uterine muscular spasm and dysmenorrhea.

Effects of adlay hull extracts on uterine contraction and Ca2+mobilization in the rat

“…The uterine smooth muscle cells were isolated using the protease and collagenase dispersion method as previously described, with some modifications (30). The uterine segments were prepared and incubated under rotation (80 rpm) at 37°C for 15 min in a HEPES buffer solution (140 mM NaCl, 5 mM KCl, 2 mM CaCl 2, 5.5 mM glucose, 10 mM HEPES, and pH adjusted to 7.4) containing 0.2% protease.…”

Biological activity and toxicity of the Chinese herb Magnolia officinalis Rehder & E. Wilson (Houpo) and its constituents

“…The effects of honokiol and magnolol on muscular contractile responses and intracellular Ca 2+ mobilization were investigated in the non-pregnant rat uterus; both lignans (at concentrations 1-100 µmol/L) inhibited spontaneous and uterotonic agonists (carbachol, PGF-2α, and oxytocin), and an experimental Ca 2+ channel activator in a concentration-dependent manner. The inhibition rate of honokiol on spontaneous contractions appeared to be slower than that of magnololinduced responses (Lu et al, 2003) (Table 8).…”

“…Magnolol and honokiol significantly inhibit the contractility of isolated gastric fundus strips of rats treated with ACH or serotonin, and of isolated ileum in guinea pigs treated with ACH or CaCl 2 ; both behave as non-competitive muscarinic antagonists. Magnolol and honokiol inhibited contractions induced by ACH (in Ca 2+ -free medium) and extracellular Ca 2+ -dependent contractions induced by ACH; this Ca 2+ blockade effect is also discussed for antiasthmatic effects in Section 3.3 (Lu et al, 2003;Chan et al, 2008;Jeong et al, 2009;Lee et al, 2011;Herrmann et al, 2014).…”

Antidiarrhea and antioxidant activities of Honokiol extract from <i>Magnoliae officinalis cortex</i> in mice

“…Lu et al reported that honokiol inhibited uterine contraction in rats by blocking external Ca 2+ influx [28]. The relaxant effect of honokiol on the tracheal smooth muscle of pig also involved blockade of Ca 2+ influx through voltage-operated Ca 2+ channels instead of Ca 2+ release from intracellular Ca 2+ stores [26].…”