Retrograde tracing of spinal cord connections to the cervix with pregnancy in mice

Abstract

In contrast to the uterus, the cervix is well innervated during pregnancy and the density of nerve fibers increases before birth. To assess neural connections between the cervix and the spinal cord, the cervix of pregnant mice was injected with the trans-synaptic retrograde neural tract tracer pseudorabies virus (PRV). After 5 days, the virus was present in nerve cells and fibers in specific areas of the sensory, autonomic, and motor subdivisions of the thoracolumbar spinal cord. In nonpregnant controls, the virus was predominantly distributed in laminae I–III in the dorsal gray sensory areas with the heaviest label in the substantia gelatinosa compared with the autonomic or motor areas. Labeled cells and processes were sparse in other regions, except for a prominent cluster in the intermediolateral column (lamina VII). Photomicrographs of spinal cord sections were digitized, and the total area with the virus was estimated. Compared with nonpregnant controls, the area with PRV was significantly decreased in all the spinal cord subdivisions in pregnant mice except in the intermediolateral column. However, areas with the virus were equivalent in mice injected with PRV at 4 days or 1 day before birth. These findings suggest that the predominant innervation of the murine cervix is from the sensory regions of the thoracolumbar spinal cord, and that these connections diminish with pregnancy. The results raise the possibility that the remaining connections from sensory and autonomic subdivisions, particularly the intermediolateral column, of the thoracolumbar spinal cord may be important for increased density of nerve fibers in the cervix as pregnancy nears term.

Transection of the Pelvic or Vagus Nerve Forestalls Ripening of the Cervix and Delays Birth in Rats1

“…Nonetheless, the finding that innervation of the cervix may influence ovarian function during pregnancy could reflect efferent control by a local and more central parasympathetic pathway [49,50]. After pelvic nerve transections, there is a loss of afferent connections to local interneurons in the thoracolumbar spinal cord [14], as well as to ascending sensory pathways in the dorsal columns and autonomic intermediolateral columns of the spinal cord that project to brainstem regions, i.e., solitary nucleus and dorsal motor nucleus. These regions receive input from the vagus nerve [17,[51][52][53].…”

“…The cervix receives sympathetic innervation from the hypogastric nerve [8,9], as well as parasympathetic projections through the pelvic and vagus nerves [10][11][12][13]. Hypogastric and pelvic nerve pathways to the cervix connect with sensory and autonomic areas in the thoracolumbar spinal cord, which have ascending connections with integrative centers in the brainstem and hypothalamus [14,15]. These integrative centers receive input from and project to the vagus nerve [16,17].…”

Optimization of the Fluorescent Protein Expression Level Based on Pseudorabies Virus Bartha Strain for Neural Circuit Tracing

“…Tracer is an important tool for mapping neural circuits. PRV152 as a trans-multisynaptic tool has been constructed by inserting the EGFP expression cassette into gG from the PRV Bartha strain (Smith et al, 2000), which has been widely used in depicting the neural network of the CNS and PNS (Collins et al, 1999; Zhang et al, 2003; Kc et al, 2006; Kirby et al, 2010; Gonzalez-Joekes and Schreurs, 2012; Chen et al, 2013; Yao et al, 2018; Jin et al, 2019). To highlight the labeled neurons, the more the EGFP amount, the better the information.…”

“…To depict the neural network, several tracers have been developed, such as Vesicular stomatitis virus and Herpes simplex virus type 1 (strain 129) can map the output information of a target brain region, while Rabies virus and Pseudorabies virus (PRV; Bartha strain) have the ability to reveal the input neural circuit. Among these tracers, the PRV Bartha strain is the only retrograde trans-multisynaptic tool, and it is indispensable to determining the input neural circuit of the CNS and PNS (Collins et al, 1999; Zhang et al, 2003; Kc et al, 2006; Zhao, 2008; Kirby et al, 2010; Gonzalez-Joekes and Schreurs, 2012; Chen et al, 2013; Griffiths, 2015; Yao et al, 2018; Jin et al, 2019).…”

Pregnancy-related changes in connections from the cervix to forebrain and hypothalamus in mice

“…2008, Boyd et al . 2009), a likely consequence of local proliferation of fibers in the cervix by fewer sensory and autonomic connections between the spinal cord and cervix as term approaches (Kirby et al . 2009).…”