The roles of the α1-adrenergic receptor subtypes in rat embryonic implantation

ObjectiveTo focus on the possible roles of α1-adrenergic receptors (α1-ARs) in rat embryonic implantation.DesignLaboratory study.SettingAnimal and pharmacology laboratory at Department of Pharmacodynamics and Biopharmacy, University of Szeged, Hungary.Animal(s)Pregnant and nonpregnant Sprague-Dawley rats.Intervention(s)Uterus tissues were collected during the peri-implantation period.Main Outcome Measure(s)We used a reverse transcription–polymerase chain reaction (RT-PCR) and Western blotting to demonstrate the expressions of mRNAs and the protein expressions of the α1-AR subtypes in the early-pregnant uterus. Electric field stimulation was applied to test the pharmacologic reactivity of the α1A-AR, and the physiologic role of this receptor was tested in a knock-down transformed animal model using an antisense oligonucleotide that elicits sequence-selective inhibition of the α1A-AR gene expression.Result(s)The presence of all α1-AR subtypes (α1A, α1B, and α1D) was proved, with a predominance of α1A-AR. The maximal expression of the α1A-AR was attained on the day of implantation. The selective α1A antagonist 5-methylurapidil inhibited the contraction in a dose-dependent manner. The number of implantation sites was decreased (∼75%) in the α1A-AR knock-down transformed rats.Conclusion(s)We assume that the α1A-AR predominance plays a crucial role in embryonic implantation in the rat.