Oxytocin stimulates cerebral blood flow in rainbow trout (Oncorhynchus mykiss) through a nitric oxide dependent mechanism.
Our knowledge of the regulation of cerebral blood flow (CBF) in ectothermic vertebrates is still very limited. In endothermic vertebrates several peptides have been shown to affect CBF through nitric oxide (NO) dependent mechanisms. Using epi-illumination microscopy in rainbow trout in vivo, we have examined the effects of topically administered oxytocin, arginine vasopressin, substance P and bradykinin on the CBF (measured as erythrocyte velocity in venules on the optic lobes). Of these peptides, only oxytocin induced a dose dependent increase in CBF velocity. Blood pressure remained unchanged and the effect was suppressed by the NOS inhibitor, N(omega)-nitro-L-arginine. This indicates that oxytocin causes NO mediated vasodilation in rainbow trout brain.
Haraldsen
Lene
L
Division of General Physiology, Department of Biology, University of Oslo, P.O. Box 1051, N-0316 Oslo, Norway.
Söderström-Lauritzsen
Veronica
V
Nilsson
Göran E
GE
D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001920:Bradykinin / Q000378:metabolism / Q000494:pharmacology; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine / Q000494:pharmacology; D017686:Oncorhynchus mykiss / Q000033:anatomy & histology / Q000378:metabolism*; D010121:Oxytocin / Q000378:metabolism* / Q000494:pharmacology; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology; D013687:Telencephalon / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; D001127:Arginine Vasopressin; D019335:Nitroarginine; D009569:Nitric Oxide; D013373:Substance P; D010121:Oxytocin; D001920:Bradykinin