title: Perivascular cells increase expression of ciliary neurotrophic factor following partial denervation of the rat neurohypophysis.
abstract: The expression of ciliary neurotrophic factor (CNTF) was investigated immunocytochemically during the axonal degeneration and collateral axonal sprouting response that follows partial denervation of the rat neurohypophysis. A significant increase in the number of CNTF-immunoreactive (CNTF-ir) cells was observed in the neurohypophysis of partially denervated animals compared to age-matched sham-operated controls by 5 days post-denervation, remaining elevated throughout the 30 day post-denervation period. Stereometric assessment of the numbers of CNTF-ir cells within the partially denervated neurohypophysis demonstrated a 36% increase by 3 days following denervation reaching 130% of control values by 10 days post-lesion. The cell numbers remained elevated throughout the 30 day post-lesion period suggesting that CNTF may play a role in the neurosecretory axonal sprouting process known to occur between 10 and 30 days post-denervation. Subsequent preparations pairing anti-CNTF with antibodies against ED1, CR3, p75 low affinity neurotrophin receptor (p75(LNGFR)), and S100beta, demonstrated that CNTF was exclusively localized in a phenotypically-distinct population of perivascular cells. The association of perivascular cells with phagocytic activity was confirmed by dual-label fluorescence microscopy showing the colocalization of P75(LNGFR)-ir and OX-42-ir in cells expressing the ED-1 antigen. No increase in CNTF-ir was observed in non-injured animals in which heightened levels of neurosecretory activity were induced physiologically. These results suggest that increased CNTF-ir occurs in response to conditions which induce high levels of phagocytic activity by perivascular cells in the axotomized neurohypophysis which is sustained throughout a period in which axonal sprouting is known to occur in the partially denervated neurohypophysis.
authors.affiliation: Department of Anatomy and Cell Biology, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, North Dakota 58203, USA.
authors.forename: David
authors.initials: D
authors.lastname: Lo
authors.forename: Neil
authors.initials: N
authors.lastname: SunRhodes
authors.forename: John A
authors.initials: JA
authors.lastname: Watt
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology / Q000502:physiology; D019771:Axotomy; D020934:Ciliary Neurotrophic Factor / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D009416:Nerve Regeneration / Q000502:physiology*; D010904:Pituitary Gland, Posterior / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020800:Receptor, Nerve Growth Factor / Q000378:metabolism
chemical_list: D020934:Ciliary Neurotrophic Factor; D020800:Receptor, Nerve Growth Factor