Identification of the neuropeptide content of individual rat neurohypophysial terminals.
The objective of this study was to develop a method that could reliably determine the arginine vasopressin (AVP) and/or oxytocin (OT) content of individual rat neurohypophysial terminals (NHT) >or=5 microm in diameter, the size used for electrophysiological recordings. We used a commercially available, highly sensitive enzyme-linked immunoassay (ELISA) kit with a sensitivity of 0.25 pg to AVP and of 1.0pg to OT. The NHT content of AVP (2.21+/-0.10 pg) was greater than OT (1.77+/-0.08 pg) and increased with terminal size. AVP-positive terminals (10.2+/-0.21 microm) were larger in diameter than OT-positive terminals (9.1+/-0.24 microm). Immunocytochemical techniques indicated that a higher percentage (58%) of smaller terminals contained OT, and that a higher percentage (42%) of larger NHTs were colabeled. Similar percentages of AVP-positive terminals were obtained between immunocytochemical (73%) and ELISA (72%) methods when NHTs were assayed for AVP alone, but there was a higher percentage of OT terminals when using immunocytochemistry (43%) compared to ELISA (26%). The percent of AVP-positive (60%) and OT-positive (18%) terminals decreased when NHT were assayed for both AVP and OT. Therefore, the best method to reliably identify AVP-positive NHTs is to assay only for AVP, since this allows the conclusion that AVP-negative terminals contain only OT.
Custer
Edward E
EE
University of Massachusetts Medical School, Department of Physiology, 55 Lake Avenue North Worcester, MA 01655, United States.
Ortiz-Miranda
Sonia
S
Knott
Thomas K
TK
Rawson
Randi
R
Elvey
Christian
C
Lee
Ryan H
RH
Lemos
José R
JR
D000818:Animals; D001127:Arginine Vasopressin / Q000032:analysis; D001681:Biological Assay / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D009434:Neural Pathways / Q000737:chemistry; D009448:Neurochemistry / Q000379:methods*; D009479:Neuropeptides / Q000032:analysis*; D010121:Oxytocin / Q000032:analysis; D010286:Paraventricular Hypothalamic Nucleus / Q000737:chemistry; D010904:Pituitary Gland, Posterior / Q000737:chemistry*; D017729:Presynaptic Terminals / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013495:Supraoptic Nucleus / Q000737:chemistry; D009435:Synaptic Transmission / Q000502:physiology
D009479:Neuropeptides; D001127:Arginine Vasopressin; D010121:Oxytocin