Dissection of Pelvic Autonomic Ganglia and Associated Nerves in Male and Female Rats

Abstract

The bilateral major pelvic ganglia (MPG; synonym, pelvic ganglia) are the primary source of postganglionic sympathetic and parasympathetic neurons innervating pelvic organs of rodents; the functionally equivalent structure in humans is the inferior hypogastric plexus. The major pelvic ganglia also provide the route by which lumbar and sacral sensory axons reach the pelvic organs. These complex, mixed ganglia can prove challenging to identify and dissect for further experimental study of normal autonomic mechanisms or to establish preclinical models of disease, injury or visceral pain. Here we describe a protocol to access and visualize these ganglia and their associated nerve tracts. We provide this protocol with schematics for both male and female rats, as the ganglion size and landmarks for identification differ between sexes. The protocol describes removal of the ganglion for in vitro studies, but this method can be integrated into a surgical recovery protocol for experimental interventions (e.g., nerve crush, nerve resection) or for mapping neuronal circuits (e.g., by microinjection of neural tracers). We also demonstrate the primary structures of the ganglion and its associated nerves immediately following dissection and following immunohistochemical staining.

Functional segregation within the pelvic nerve of male rats: a meso‐ and microscopic analysis

“…Relevant organs were removed to confirm the location of the injection site(s) and MPGs (with associated nerves) dissected (Bertrand and Keast, 2020). During post-fixation (1 h), the MPGs were secured with micropins to a dish lined with silicon polymer, to retain the shape and orientation of their major components.…”

Impairment of accessory nerves around major pelvic ganglion leading to overflow urinary incontinence in rats

“…It contains a collection of autonomic nerves that project to the tissues of the lower urinary tract and the reproductive organs. 8 The hypogastric and pelvic nerves travel through the MPG before reaching target tissues, such as the bladder and urethra. 9 There are several reports about the involvement of these nerves in lower urinary tract function.…”

“…The major pelvic ganglion (MPG) of rats is similar in function to the inferior hypogastric plexus in humans. It contains a collection of autonomic nerves that project to the tissues of the lower urinary tract and the reproductive organs 8 . The hypogastric and pelvic nerves travel through the MPG before reaching target tissues, such as the bladder and urethra 9 .…”

Neuroscience tools in novel contexts: developing thermogenetics in Drosophila and decoding autonomic activity in mouse major pelvic ganglion

“…We found male mice to be easier to work with as they have less visceral fat providing additional physical space in the pelvic cavity, one of the major limitations of using mice relative to rats. Moreover, MPGs are more easily identifiable in males compared to females (Bertrand, and Keast, 2020).…”

“…As seen in Figure 10A, cholinergic parasympathetic preganglionic neurons are located in the brainstem and sacral spinal cord and send their axonal projections via the pelvic nerve, whereas noradrenergic sympathetic pathways have preganglionic neurons in the thoracic-lumbar spinal cord and send their axonal projections via the hypogastric nerve (Bertrand, and Keast, 2020;Keast et al, 1995;Wanigasekara et al, 2003). Neurotransmission of autonomic signals between the central nervous system and the lower urinary tract primarily occurs at two locations: 1) the major pelvic ganglion (MPG) (shown in Figure 10A and 10B), a peripheral tissue that contains postganglionic parasympathetic neurons (Figure 10C) that innervate the bladder, genitals, and distal colon (Keast, 1995;Purinton et al, 1973), and 2) the inferior plexus, the major site of postganglionic sympathetic neurons which innervate the bladder, urethra, and internal sphincter (Fowler et al, 2008;Inskip et al, 2009;Keast, 1999) (Figure 10A).…”