Changes in electrical activity of myometrium during intrauterine distribution of rat blastocysts and after prazosin administration

C. Legrand, A. Banuelos-Nevarez, J. P. Maltier
1989 Reproduction  
In the early pregnant rat, electrical activity of the myometrium consisted of regular bursts of spike potential, which appeared well propagated on Day 2 of pregnancy. During Day 3, there was a gradual disappearance of propagated activity. Concomitantly, there was a 7-fold increase (P < 0\m=.\001) of uterine progesterone concentrations. At this stage, mean duration of bursts was 15\m=.\2\ m=+-\0\m=.\9sec and intervals of complete quiescence between bursts were 84\m=.\2\m=+-\7\m=.\0sec. At 10:00
more » ... m=.\0sec. At 10:00 h on Day 4, there were peaks in the uterine concentrations of oestradiol and progesterone, + 36% and + 654%, respectively, compared with values on Day 2 (P < 0\m=.\05). Between 10:00 and 20:00 h on Day 4, EMG activity exhibited a rapid and transient rise: bursts were of longer duration at the utero-tubal end of the horn (+ 60%, p < 0\m=.\05) with an increased amplitude of spike potentials ( + 67% and +90% respectively at the tubal and cervical ends of the uterus, P < 0\m=.\05). The administration of prazosin depressed EMG activity reversibly in a dose-dependent manner with maximal inhibition at about 2\p=n-\3h later. It is concluded that the changes observed during EMG recordings are relevant to the intrauterine distribution of blastocysts and related to changes in the steroidal environment and/or to catecholamine effects via \g=a\1-adrenoceptors.
doi:10.1530/jrf.0.0860039 fatcat:aijojujtwjhf7j6vaq4ckdjzvu