The effects of arginine-8 vasopressin on the cerebral cortex of rats anaesthetised with urethane.
The effects of arginine-8 vasopressin (AVP) on the spontaneous electrical activity of the cerebral cortex were investigated in rats anaesthetised with urethane. Direct application of a relatively large concentration of AVP (0.5-2.0 mU AVP/microliter; 1.25-5.00 ng AVP/microliter) to the pial surface of a small area of the parietal cortex produced a complete cessation of spontaneous neural activity, which was often preceded by a short-lasting increase in frequency of discharge. There was also a decline in the number of large waves in the local electrocorticogram. These changes occurred after 1-4 min. A slow recovery began 10-30 min later, but was sometimes still incomplete after more than an hour. Only the first application of AVP produced the local effects described above. A second application, 2 hr later, was without effect. Direct application to a small area of one hemisphere did not alter the electrical activity of the contralateral cortex. Smaller concentrations of AVP (0.005-0.200 mU AVP/microliter; 12.5 pg-0.5 ng AVP/microliter) were variable in their actions. Occasionally, no effect at all was seen, while sometimes the cells stopped firing completely. However, the most usual consequence was a reduction in discharge frequency, the magnitude of which appeared to be related to the concentration of AVP applied. A second application of a small concentration of AVP usually failed to reduce the rate of spontaneous discharge.
A C
AC
Webb
I S
IS
Ebenezer
B D
BD
Burns
D000818:Animals; D001127:Arginine Vasopressin / Q000008:administration & dosage / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects*; D004347:Drug Interactions; D004569:Electroencephalography; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013618:Tachyphylaxis; D014520:Urethane / Q000494:pharmacology*
D001127:Arginine Vasopressin; D014520:Urethane