Cardiovascular effects of intraventricular injection of FMRFamide, Met-enkephalin and their common analogues in the rat.
The molluscan neuropeptide, Phe-Met-Arg-Phe-NH2 (FMRFamide), the mammalian opioid peptide met-enkephalin, and their common analogues, met-enkephalin-Arg6-Phe7 (YGGFMRF) and Tyr-Gly-Gly-Phe-Met-Arg-Phe-amide (YGGFMRFamide), were injected into the lateral ventricle of the rat; the cardiovascular effects were studied. FMRFamide caused a rapid, transient elevation in blood pressure accompanied by a great increase in pulse pressure. These effects were followed by secondary increases in blood and pulse pressures. Met-enkephalin produced an initial reduction in blood pressure which was followed by a gradual increase at the higher of two test doses (300 nmole). Injection of YGGFMRF resulted in a gradual increase in blood pressure. This response resembled that to met-enkephalin. The initial response to YGGFMRFamide was similar to that to FMRFamide: increases in both blood and pulse pressures after injection. However, the secondary effect of YGGFMRFamide, a prolonged reduction in blood pressure, was not produced by FMRFamide. These results suggest that the initial excitatory cardiovascular responses may be due to the presence of the C-terminal amide. All of the cardiovascular effects of injecting these peptides into the lateral ventricle were abolished by pre-treatment with naloxone in a dose that, itself, produced no cardiovascular changes. In conclusion, these peptides seem to act via the naloxone sensitive opiate receptors in the rat brain.
Wong
T M
TM
Greenberg
M J
MJ
Tse
S Y
SY
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology*; D019835:FMRFamide; D007276:Injections, Intraventricular; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D013329:Structure-Activity Relationship
D009842:Oligopeptides; D009270:Naloxone; D004744:Enkephalin, Methionine; D019835:FMRFamide; C027511:enkephalin-Met, Arg(6)-Phe(7)-; C033460:enkephalin-Met, Arg(6)-PheNH2(7)-