Pituitary adenylate cyclase-activating polypeptide (PACAP): a novel regulator of vasopressin-containing neurons.
Pituitary adenylate cyclase-activating polypeptide (PACAP) was localized in nerve terminals that innervate arginine-vasopressin (AVP)-containing neurons in the rat hypothalamic supraoptic nucleus (SON). PACAP receptor (PACAPR) mRNA was expressed at high-levels in AVP-containing neurons in the SON, but at very low-levels in oxytocin-containing neurons. PACAPR-like immunoreactivity was found in SON and it was observed in the post-synaptic membranes as well as on the rough endoplasmic reticulum and cytoplasmic matrices in the magnocellular neurons. Doses of PACAP in the nanomolar range increased cytoplasmic Ca2+ concentrations ([Ca2+]i) in AVP-containing neurons; the increase in [Ca2+]i was inhibited by a protein kinase A blocker. These findings suggest that PACAP serves as a transmitter and/or modulator and the activation of PACAPR stimulates a cAMP-protein kinase A pathway which in turn evokes the Ca2+ signaling system. It is hypothesized that PACAP regulates the functions of AVP-containing neurons which participate in the control of plasma osmolarity and blood pressure.
Shioda
S
S
Department of Anatomy, Showa University School of Medicine, Tokyo, Japan. shioda@med.showa-u.ac.jp
Yada
T
T
Nakajo
S
S
Nakaya
K
K
Nakai
Y
Y
Arimura
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D009412:Nerve Fibers / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D009479:Neuropeptides / Q000502:physiology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D015347:RNA Probes; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology; D013495:Supraoptic Nucleus / Q000166:cytology / Q000378:metabolism; D014667:Vasopressins / Q000378:metabolism / Q000502:physiology*
C495403:Adcyap1 protein, rat; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D015347:RNA Probes; D014667:Vasopressins; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium