Innervation of the rat anterior and neurointermediate pituitary visualized by immunocytochemistry for the growth-associated protein GAP-43.
Immunocytochemical localization of the neuronal growth associated protein GAP-43 revealed a dense axonal plexus throughout the neurointermediate lobe of the rat pituitary. These axons were fine, presumably monoaminergic fibers, whereas magnocellular neurosecretory axons did not appear to contain detectable GAP-43. These experiments also revealed the presence of an extensive nerve plexus within the anterior lobe. Fine beaded fibers were present throughout the parenchyma of the anterior lobe, and punctate staining suggestive of nerve terminals was seen surrounding numerous endocrine cells. Nerve fibers did not appear to cross directly between the intermediate and anterior lobes, but rather entered the anterior lobe directly from its margins or in association with blood vessels. Preabsorption of antisera with GAP-43 purified from neonatal rat brain completely eliminated immunoreactivity. These findings confirm the existence of a direct innervation of the anterior pituitary of the rat; moreover, the presence of GAP-43 in these fibers suggests that they may be capable of growth and terminal reorganization in the adult animal.
Paden
C M
CM
Dept. of Biology, Montana State University, Bozeman 59717.
Moffett
C W
CW
Benowitz
L I
LI
D000818:Animals; D019922:GAP-43 Protein; D006133:Growth Substances / Q000032:analysis; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000032:analysis*; D009419:Nerve Tissue Proteins / Q000032:analysis*; D010903:Pituitary Gland, Anterior / Q000737:chemistry* / Q000294:innervation*; D010904:Pituitary Gland, Posterior / Q000737:chemistry* / Q000294:innervation*; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
D019922:GAP-43 Protein; D006133:Growth Substances; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins