Irritative Deposits from Stainless Steel Electrodes in the Preoptic Rat Brain Causing Release of Pituitary Gonadotropin.

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Abstract
Rats in which spontaneous ovulation is blocked by pentobarbital can be induced to ovulate by stimulation of the hypothalamus or certain related parts of the brain. In a standardized procedure, when the stimulus was induced by stainless steel electrodes in the preoptic area, delivering pulses of varied characteristics, a prominent zone of mild inflammation appeared at the end of the electrode track. When ovulation failed, the zone was characteristically small or absent. Electrolysis with direct current, 10 UA or more for 20 sec or longer, proved uniformly effective in causing ovulation. Substitution of platinum for stainless steel usually gave negative results. Microinjection of FeCl3 into the preoptic tissue induced ovulation, by contrast with controls receiving acidified NaCl. Finally, electrolysis stimulated ovulation when electrodes of reagent grade iron wire were used, but not when similar electrodes of platinum were employed. It is concluded that iron and perhaps other metals electrolytically deposited from electrodes of stainless steel (or nichrome) produce irritative foci whose stimulative action on certain neurons continues long after the flow of electric current has ceased.