Cumulative effect of prostaglandin E2(PGE2) injections on electroencephalographic activity in male monkeys (Macaca mulatta).

Bipolar stainless steel electrodes were stereotaxically implanted in hypothalamic and cerebral cortical regions of 24 adult male gonadally intact monkeys. Electrical activity of these regions was recorded before and after the first, second, third, thirteenth, fourteenth and fifteenth day of intravenous (I. V.) injection of PGE2 (400 mikrogramm/kg body weight). The inferences drawn from the EEG record were: (i), the immediate response was a tendency towards spindle formation (ii), high voltage spindles appeared at regular intervals in all sites i.e., preoptic area, posterior hypothalamus, ventromedial nucleus and cerebral cortex (iii), the changes observed. in EEG were progressive with time and transitional with respect to various regions of the brain (iv), these changes were synchronized whenever and wherever they were present, but the generalized showing in the form of overall inhibition could never be seen (v), the dose showed a cumulative effect after repeated daily injections of PGE2.