Electroconvulsive shock raises prostaglandins F in rat cerebral cortex.

'101 The prostaglandins are potent autacoids which are widely distributed in mammalian tissues [I] including the central nervous system of various species [2-43. Although tissue stores are quite small, prostaglandins (PG's) are rapidly synthesized and released in association with peripheral nerve stimulation [S]. Several groups of workers have reported that PG's and PG-like substances are released from the central nervous system spontaneously and subsequent to electrical or pharmacological stimulation [6 IO]. Among these was a report that an unidentified substance. which contracted rat fundus strip in the presence of a serotonin antagonist, was released into the lateral ven-tricles of cats during convulsions caused by pcntylenetetra-zol and strychnine [l I]. The present study demonstrates striking and rapid increases in cortical levels of PG's of the F series induced by electroconvulsive shock (ECS). The increased level seems to reflect a rapid increase in synthesis. Pretreatment with indomethacin, an inhibitor of PG biosynthesis [12,13], blocked the increase induced by ECS. PC's and their metabolites were provided by Dr. within 1 hr of use by dissolving the powder in alkaline solution and titrating the pH back to 7.4. ECS was delivered to awake animals through gold-plated silver electrodes for @2 set (7&90 V) placed trans-corneally or pressed against the scalp biparietally. Male SpragueeDawley rats. obtained from Charles River, Inc. and weighing approximately 200 g. were killed by decapitation and their cerebral cortices quickly removed and frozen on dry ice. Frozen tissue was weighed and then homogenized in 0.01 M sodium phosphate buffer. pH 7.4, at 0 ". 3H-PG-F, was added to an aliquot of homo-genate to follow recoveries. The samples were acidified with 1 N HCI and washed with light petroleum ether. PG's were extracted twice into 5 vol. of redistilled ethyl acetate. The dried samples were taken up in benzene-ethyl acetate-methanol (60:40: IO) and placed on a 0.5-g silicic acid column. The PG's were separated and eluted by increasingly polar solvent mixtures in discontinuous steps. PG-A's and less polar lipids wcrc eluted with 4 ml benzene-ethyl acetate (60:40), PG-E's with 14 ml benzeneeethyl acetate methanol (60:40:2). and PG-F's with 4.5 ml bcnrcne-ethyl acetate-methanol (60:40:X)) [ 141. Dried eluates were taken up in alcohol. diluted and dried again under Nz prior to radioimmunoassay. Prostaglandins were not measurably extracted into petroleum ether. Ethyl acetate extracted 8@ 90 per cent from the acidified aqueous solution. Less than 4 per cent of PC-F was eluted in the …