Abstract
The aim of this study was to investigate the effects of pomegranate (Punica granatum L., Punicaceae) seed extract on uterine contractility. Pomegranate seeds were methanolic extracted and their constituents analyzed using gas chromatography and mass spectrometry. Isometric force was measured in strips of longitudinal rat myometrium and the effects of pomegranate seed extract studied. We found β-sitosterol to be the main constituent of the extract (16%) and its effects were also investigated. Pomegranate seed extract and β-sitosterol increased spontaneous contractions in a concentration-dependent manner with a maximum effect at 250 mg/100 mL and 1 mg/100 mL, respectively. The amplitude and frequency of the phasic contraction were significantly increased along with basal tension. The effects of pomegranate seed extract were very similar to those of β-sitosterol. Force produced in the presence of pomegranate seed extract was abolished by the inhibition of L-type calcium channels or myosin light chain kinase (MLCK). Contractions were not potentiated by pomegranate extract following the inhibition of K channels or inhibition of the sarcoplasmic reticulum calcium ATPase (SERCA). The actions of β-sitosterol and the extract were not blocked by the estrogen receptor blocker, fulvestrant. We conclude that pomegranate seed extract is a potent stimulator of phasic activity in rat uterus. Our data suggest that the uterotonic effect is due to nonestrogenic effects of β-sitosterol acting to inhibit K channels and SERCA and thereby increasing contraction via calcium entry on l-type calcium channels and MLCK. We suggest that pomegranate extract and β-sitosterol may be a useful uterine stimulant.
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References
Langley P. Why a pomegranate? BMJ. 2000;321(7269): 1153–1154.
Gil MI, Tomás-Barberán FA, Hess-Pierce B, Holcroft DM, Kader AA. Antioxidant activity of pomegranate juice and its relationship with phenolic composition and processing. J Agric Food Chem. 2000;48(10):4581–4589.
Schubert SY, Lansky EP, Neeman I. Antioxidant and eicosanoid enzyme inhibition properties of pomegranate seed oil and fermented juice flavonoids. J Ethnopharmacol. 1999; 66(1):11–17.
van Elswijk DA, Schobel UP, Lansky EP, Irth H, van der Greef J. Rapid dereplication of estrogenic compounds in pomegranate (Punica granatum) using on-line biochemical detection coupled to mass spectrometry. Phytochemistry. 2004;65(2):233–241.
Kim ND, Mehta B, Yu W, et al. Chemopreventive and adjuvant therapeutic potential of pomegranate (Punica granatum) for human breast cancer. Breast Cancer Res Treat. 2002;71(3): 203–217.
Jurenka JS. Therapeutic applications of pomegranate (Punica granatum L.): a review. Altern Med Rev. 2008;13(2):128–144.
Moneam NM, el Sharaky AS, Badreldin MM. Oestrogen content of pomegranate seeds. J Chromatogr. 1988;438(2): 438–442.
Sharaf A, Nigm SA. The oestrogenic activity of pomegranate seed oil. J Endocrinol. 1964;29:91–92.
Wray S, Kupittayanant S, Shmigol A, Smith RD, Burdyga TV. The physiological basis of uterine contractility: a short review. Exp Physiol. 2001;86(2):239–246.
Bao L, Li Y, Deng SX, Landry D, Tabas I. Sitosterol-containing lipoproteins trigger free sterol-induced caspase-independent death in ACAT-competent macrophages. J Bio Chem. 2006;281(44):33635–33649.
Shmygol A, Noble K, Wray S. Depletion of membrane cholesterol eliminates the Ca2+-activated component of outward potassium current and decreases membrane capacitance in rat uterine myocytes. J Physiol Lond. 2007;581(pt 2):445–456.
Promprom W, Kupittayanant S, Indrapichate K, Kupittayanant P. Effects of pomegranate extracts on rat uterine contraction. Planta Med. 2007;73:1007.
Longbottom ER, Luckas MJM, Kupittayanant S, Badrick E, Shmigol A, Wray S. The effects of inhibiting myosin light chain kinase on contraction and calcium signalling in human and rat myometrium. Pflugers Arch. 2000;440(2):315–321.
Shmigol A, Eisner DA, Wray S. Properties of voltage-activated [Ca2+]i transients in single smooth muscle cells isolated from pregnant rat uterus. J Physiol Lond. 1998;511(pt 3): 803–811.
Kupittayanant S, Luckas MJ, Wray S. Effect of inhibiting the sarcoplasmic reticulum on spontaneous and oxytocin-induced contractions of human myometrium. BJOG. 2002;109(3): 289–296.
Buzdar AU. Fulvestrant—a novel estrogen receptor antagonist for the treatment of advanced breast cancer. Drugs Today (Barc). 2008;44(9):679–692.
Kakui K, Itoh H, Sagawa N, et al. Augmented endothelial nitric oxide synthase (eNOS) protein expression in human pregnant myometrium: possible involvement of eNOS promoter activation by estrogen via both estrogen receptor (ER) alpha and ERbeta. Mol Hum Reprod. 2004;10(2):115–122.
Cassidy A. Dietary phytoestrogens-potential anti-cancer agents? BNF Nutr Bull. 1999;24:22–31.
Wray S. Insights into the uterus. Exp Physiol. 2007;92: 621–631.
Oishi K, Takano-Ohmuro H, Minakawa-Matsuo N, et al. Oxytocin contracts rat uterine smooth muscle in Ca2+-free medium without any phosphorylation of myosin light chain. Biochem Biophys Res Commun. 1991;176(1):122–128.
Heaton RC, Wray S, Eisner DA. Effects of metabolic inhibition and changes of intracellular pH on potassium permeability and contraction of rat uterus. J Physiol Lond. 1993;465: 43–56.
Wray S, Burdyga T, Noble K. Calcium signalling in smooth muscle. Cell Calcium. 2005;38(3–4):397–407.
Taggart MJ, Wray S. Contribution of sarcoplasmic reticular calcium to smooth muscle contractile activation: gestational dependence in isolated rat uterus. J Physiol Lond. 1998; 511(pt 1):133–144.
Wang CT, Caruso RL. ∝-Tocopherol inhibits activation of the ε isoform of protein kinase C and NADPH oxidase-mediated generation of superoxide anion redicals in lindane-exposed myometrium. Annual Meeting of the Society for the Study of Reproduction, Pullman, WS; 1999.
Zhang J, Kendrick A, Quenby S, Wray S. Contractility and calcium signalling of human myometrium are profoundly affected by cholesterol manipulation: implications for labour? Reprod Sci. 2007;14(5):456–466.
Borges AC, Feres T, Vianna LM, Paiva TB. Recovery of impaired K+ channels in mesenteric arteries from spontaneously hypertensive rats by prolonged treatment with cholecalciferol. Br J Pharmacol. 1999;127(3):772–778.
Noble K, Matthew A, Burdyga T, Wray S. A review of recent insights into the role of the sarcoplasmic reticulum and Ca entry in uterine smooth muscle. Eur J Obstet Gynecol Reprod Biol. 2009;144(suppl 1):11–19.
Burdyga T, Wray S, Noble K. In situ calcium signaling: no calcium sparks detected in rat myometrium. Ann N Y Acad Sci. 2007;1101:85–96.
Olson ML, Kargacin ME, Honeyman TW, Ward CA, Kargacin GJ. Effects of phytoestrogens on sarcoplasmic/endoplasmic reticulum calcium ATPase 2a and Ca2+ uptake into cardiac sarcoplasmic reticulum. J Pharmacol Exp Ther. 2006; 316(2):628–635.
Quenby S, Pierce SJ, Brigham S, Wray S. Dysfunctional labor and myometrial lactic acidosis. Obstet Gynecol. 2004;103(4): 718–723.
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Promprom, W., Kupittayanant, P., Indrapichate, K. et al. The Effects of Pomegranate Seed Extract and β-Sitosterol on Rat Uterine Contractions. Reprod. Sci. 17, 288–296 (2010). https://doi.org/10.1177/1933719109352687
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DOI: https://doi.org/10.1177/1933719109352687


