Pregnancy-induced uterine neuronal degeneration in the rat

Abstract

We studied the location, distribution, and density of uterine nerve bundles in virgin, full-term pregnant, and early postpartum female rats. In the virgin, a low-magnification analysis of uterine whole-mounts stained for acetylcholinesterase revealed fibers both in close association with blood vessels and coursing freely within muscle or connective tissue in the mesometrium and the uterine body. Higher magnification analysis of sections treated immunohistochemically with antibodies to the ubiquitous neuronal protein gene product 9.5, tyrosine hydroxylase, and calcitonin gene-related peptide indicated that the greatest density of nerve bundles was in the mesometrial triangle and intramyometrial region. Although the majority of bundles were associated with blood vessels, many coursed freely, particularly in the myometrial and endometrial layers. The density of innervation within the body of the uterus was heterogeneous. For instance, both innervated and noninnervated spiral arteries branched from the same innervated circumferential artery. In the term pregnant rat, we observed a profound denervation within all layers of the body of the uterus. The few remaining nerve bundles tended to be associated with blood vessels, and they were confined to the intramyometrial region. Within 48 h postpartum, both the number and density of nerve bundles increased. Long tortuous bundles, not seen in the full-term rat, were observed. The present study is the first to describe and illustrate the pattern of uterine innervation in virgin, full-term pregnant, and early postpartum rats over a wide range of magnifications.

Effects of Infantile/Prepubertal Chronic Estrogen Treatment and Chemical Sympathectomy with Guanethidine on Developing Cholinergic Nerves of the Rat Uterus

“…Several studies have led to the concept that AChE staining is not a reliable marker for cholinergic nerves (Garfield 1986;Papka et al 1999), because AChE histochemistry has also been shown to stain sympathetic (Haase et al 1997) and primary afferent sensory nerve fibers (Papka et al 1981). In addition, it has been demonstrated that, in several target organs, postganglionic sympathetic and parasympathetic nerve fibers run closely juxtaposed within a common Schwann cell sheath (Ehinger and Falk 1966;Ehinger et al 1970;Elbadawi 1984;Levi 1990).…”

A role of stretch-activated potassium currents in the regulation of uterine smooth muscle contraction

“…However, we have known for some time that the uterus becomes essentially denervated during gestation [4] and as a result, it is unlikely that any coordinated nervous regulation of the myometrium is centrally orchestrated [5] . As a result, views of the origin of onset of labor turned early on to examine endocrine and paracrine mechanism of myometrial regulation.…”

Innervation of the rat uterus at estrus: A study in full‐thickness, immunoperoxidase‐stained whole‐mount preparations

“…For example, Papka et al (1985) were unable to analyze whole mounts extensively because of their thickness and the many different focal planes that needed to be examined and photographed. Haase et al (1997) examined acetylcholinesterase (AChE)-stained uterine whole-mount preparations floating in glycerin with a dissecting microscope and needed careful manipulation of light sources for assessment. Nevertheless, these authors were only able to publish low-magnification diagrams of AChE staining, which contained little detail about the actual trajectories of cholinesterase-positive nerve bundles and axons.…”