Dystocic Labor and Adrenergic and Noradrenergic Neurotransmitters: A Morphological Experimental Study

Abstract

Authors investigated the catecholaminergic neurotransmitters (chNs) quantitative modifications in pregnant uterine Lower Uterine Segment (LUS) during prolonged labor (PL) with the fetus in an occiput-posterior position (OPP), in occiput transverse position (OTP) and in fetal head asynclitism, all diagnosed by Intrapartum Ultrasonography (IU). The chNs neurotransmitters, particularly adrenaline (or epinephrine-A) and noradrenaline (or norepinephrine-N), were evaluated in LUS fragments sampled during CS of 34 patients undergoing urgent cesarean section (CS) in PL, compared to chNs fibers in the LUS of 36 women submitted to elective CS. All results were statistically analyzed to understand the differences in neurotransmitters morphological analysis by scanning electronic microscopy examination (SEM). The LUS fragments analysis revealed a reduction of A and N fibers in LUS during PL, compared with the expression of A and N fibers in LUS during elective CS. The PL for OPP, the OTP and asynclitism, all positions causing dystocia in labor lead to a reduction in neurotransmitters in LUS, with a uterine vascularization modification and a reduction in the contractility of smooth uterine cells. The A and N neurotransmitters reduction observed in PL negatively interferes with uterine contraction during labor.

Localization of Catecholaminergic Neurofibers in Pregnant Cervix as a Possible Myometrial Pacemaker

“…Thus, epinephrine and norepinephrine can stimulate, alter, and regulate myometrial activity in humans, although their physiologic and therapeutic importance is doubtful [ 54 ]. Malvasi et al showed, in the dystocic prolonged labor, a reduction in adrenergic and noradrenergic neurofibers, determining an alteration in the vascularization of the LUS and, consequently, uterine contractility [ 55 , 56 , 57 ].…”

Prolonged Dystocic Labor in Neuraxial Analgesia and the Role of Enkephalin Neurotransmitters: An Experimental Study

“…Hu et al [ 25 ] demonstrated that fetal distress is associated with endogenous opioids, measuring concentrations of plasmatic endogenous opioid neuropeptides (EOP), such as beta-endorphin, endorphin A [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ], and leu-enkephalin, measured by radioimmunoassay. They detected that the modifications in EOP levels in umbilical artery may play an important role in fetal distress, in the pathophysiological changes [ 25 ].…”

“…Malvasi et al [ 2 , 3 ] demonstrated the presence of neuro fibers and neurotransmitters in the Lower Uterine Segment (LUS), in the uterine scar in greater density. Moreover, Malvasi et al [ 4 ] showed that in Prolonged Dystocic Labor (PDL) there is a reduction in adrenergic and noradrenergic neuro fibers and neurotransmitters in the LUS.…”

Oxytocin augmentation and neurotransmitters in prolonged delivery: An experimental appraisal

“…The impact of dystocia and the tensile characteristics and changes of the LUS in previous caesarean scars were documented by Buhimschi et al [6] . Malvasi et al revealed that in the PDD there is a morphometric reduction of adrenergic fibers, evaluated by SEM and FM [7] , and of enkephalinergic neurofibers in comparison to non-progressive dystocic labor (NPDD) [8] . This study investigated, by SEM and FM, the presence of oxytocinergic Nfc in NPDD and PDD during cesarean section (CS).…”