Substance P- and vasoactive intestinal polypeptide (VIP)-immunoreactive nerve fibers in relation to ovarian postganglionic perikarya in para- and prevertebral ganglia: Evidence from combined retrograde tracing and immunocytochemistry

Summary Retrograde neuronal tracing with the fluorescent dye True Blue and immunocytochemistry were utilized to examine postganglionic sympathetic neurons in para- and prevertebral ganglia projecting to the rat ovary. Perikarya in both ganglia were labeled with True Blue after application of the tracer to either the superior ovarian or ovarian plexus nerve. After application of True Blue to the superior ovarian nerve, 17% of the labeled cells in paravertebral ganglia were immunoreactive for vasoactive intestinal polypeptide. In contrast, after application of True Blue to the ovarian plexus nerve, approximately 1 % of the labeled cells in paravertebral ganglia were immunoreactive for the same polypeptide. Some vasoactive intestinal polypeptide-immunoreactive perikarya in paravertebral ganglia were not labeled with True Blue. In some cases, substance P- and vasoactive intestinal polypeptide-immunoreactive fibers were closely apposed to True Blue-labeled perikarya in para-and prevertebral ganglia. Paravertebral vasoactive intestinal polypeptide-immunoreactive perikarya projecting to the ovary presumably participate directly in the control of various ovarian functions. Substance P- and vasoactive intestinal polypeptide-immunoreactive fibers closely apposed to perikarya projecting to the ovary may participate indirectly in the control of various ovarian functions by affecting the activity of ovarian postganglionic neurons.     

Light- and electron-microscopic study of synaptic connections in the paracervical ganglion of the female rat: special reference to calcitonin gene-related peptide-, galanin- and tachykinin (substance P and neurokinin A)-immunoreactive nerve fibers and terminals

Nerve fibers and varicosities in the pelvic paracervical ganglia (PG) are immunoreactive for the neuropeptides calcitonin gene-related peptide, galanin, and the tachykinins substance P and neurokinin A. Many of these fibers and varicosities are capsaicin-sensitive, originate in dorsal root ganglia and, thus, are considered to be primary afferent fibers. Numerous immunoreactive varicosities are pericellular to principal neurons in the PG. The present study examines the ultrastructure of calcitonin gene-related peptide-, galanin-, substance P-, and neurokinin A-immunoreactive nerve fibers and varicosities in the ganglia to determine their relationships to principal neurons and their synaptic connectivity. Paracervical ganglia of female rats were processed for light-microscopic immunohistochemistry using antisera against synapsin I, as a nerve terminal marker, and microtubule-associated protein-2 to define soma and dendrites. The rationale for performing this co-immunohistochemical analysis was to reveal the relationship between nerve endings and principal neurons. Synapsin I endings were predominantly axosomatic with fewer being axodendritic. Other ganglia were processed for electron-microscopic immunohistochemistry using both standard immunogold and peroxidase-anti-peroxidase procedures. Unmyelinated fibers and varicosities immunoreactive for calcitonin gene-related peptide, galanin, and the tachykinins were routinely observed in the interstitium between neuron somas. Numerous immunoreactive axon profiles were present in small groups that were ensheathed by Schwann cells. Immunoreactive fibers and varicosities were also observed within the satellite-cell sheath of the neuron soma and often intimately associated with the membrane of the soma, somal protrusions, or with the proximal part of a dendrite. Membrane specializations, indicative of synaptic contacts, between the fibers and the principal neurons were observed. It is suggested that these peptide-immunoreactive sensory fibers and varicosities are involved in regulation of activity in the PG.