A study found that 5β-DHP, but not progesterone, directly bound to and antagonized the oxytocin receptor at nanomolarconcentrations, and it was suggested that this may be one of the mechanisms by which progesterone maintains pregnancy.[15][16][17] However, a subsequent study was unable to replicate this finding, and there has been no further investigation since.[16] In any case, 5β-DHP has nonetheless been shown to possess tocolytic effects in animals, and this may alternatively be mediated by activation of the PXR.[12]
^Gilbert Evans, Susan E.; Ross, Lori E.; Sellers, Edward M.; Purdy, Robert H.; Romach, Myroslava K. (2005). "3α-reduced neuroactive steroids and their precursors during pregnancy and the postpartum period". Gynecological Endocrinology. 21 (5): 268–279. doi:10.1080/09513590500361747. ISSN0951-3590. PMID16373246. S2CID71722314.
^Sheehan PM, Rice GE, Moses EK, Brennecke SP (2005). "5 Beta-dihydroprogesterone and steroid 5 beta-reductase decrease in association with human parturition at term". Mol. Hum. Reprod. 11 (7): 495–501. doi:10.1093/molehr/gah201. PMID16123077.
^ abOcvirk, Rok; Pearson Murphy, Beverley E.; Franklin, Keith B.J.; Abbott, Frances V. (2008). "Antinociceptive profile of ring A-reduced progesterone metabolites in the formalin test". Pain. 138 (2): 402–409. doi:10.1016/j.pain.2008.01.019. ISSN0304-3959. PMID18343034. S2CID32370572.
^Morris KD, Moorefield CN, Amin J (1999). "Differential modulation of the gamma-aminobutyric acid type C receptor by neuroactive steroids". Mol. Pharmacol. 56 (4): 752–9. PMID10496958.
^ abMitchell, Bryan F.; Mitchell, Jana M.; Chowdhury, Jeeshan; Tougas, Michelle; Engelen, Sanne M.E.; Senff, Nancy; Heijnen, Iris; Moore, John T.; Goodwin, Bryan; Wong, Susan; Davidge, Sandra T. (2005). "Metabolites of progesterone and the pregnane X receptor: A novel pathway regulating uterine contractility in pregnancy?". American Journal of Obstetrics and Gynecology. 192 (4): 1304–1313. doi:10.1016/j.ajog.2005.01.040. ISSN0002-9378. PMID15846226.
^Lima-Hernández, Francisco J.; Beyer, Carlos; Gómora-Arrati, Porfirio; García-Juárez, Marcos; Encarnación-Sánchez, José L.; Etgen, Anne M.; González-Flores, Oscar (2012). "Src kinase signaling mediates estrous behavior induced by 5β-reduced progestins, GnRH, prostaglandin E2 and vaginocervical stimulation in estrogen-primed rats". Hormones and Behavior. 62 (5): 579–584. doi:10.1016/j.yhbeh.2012.09.004. ISSN0018-506X. PMID23010621. S2CID40245594.
^Illingworth DV, Elsner C, De Groot K, Flickinger GL, Mikhail G (February 1977). "A specific progesterone receptor of myometrial cytosol from the rhesus monkey". J. Steroid Biochem. 8 (2): 157–60. doi:10.1016/0022-4731(77)90040-1. PMID405534.