METABOLISM IN CHANGED CEREBRAL ACTIVITY 65 



triethyl tin resembles that of the barbiturates and may possibly be 

 a reflection of the fall in tissue temperature produced by these 

 substances (Stoner and Threlfall, 1958). 



Dinitro-o-cresol, toxic to man where death is accompanied 

 by extreme rigor, also affects levels of cerebral phosphates 

 (Parker, 1954). In rats, killed by injection of the dinitrocresol the 

 quantities of phosphocreatine and adenosine triphosphate fell from 

 normal levels to 0-3-0-6(i, moles/g wet wt. tissue, while levels of 

 adenosine monophosphate increased. Such an effect is in accord 

 with the known ability of this compound to " uncouple " oxidative 

 phosphorylation (pp. 81—82) and thus decrease the levels of 

 adenosine triphosphate and phosphocreatine. 



The entry and metabolism of phosphate in cerebral tissue 

 appears to be partly under hormonal control. In the rat during 

 pro-oestrus there is a significant increase in radioactive phosphate 

 uptake in the tubercinereum as compared with the uptake during 

 any other stage of the oestrus cycle (Borell and Ostrom, 1947). 

 Corticotrophic hormone exerts a regulatory function on the 

 phosphate uptake of grey matter, olfactory bulb and the pineal 

 gland in the rat (Reiss et al., 1949). Hypophysectomy reduced the 

 uptake of intravenously injected phosphate into the olfactory bulb 

 but increased it in grey matter and in the pineal gland. Values were 

 brought to normal if corticotrophic hormone was administered 1 hr 

 before radioactive phosphate. The changes were not confined to 

 acid-soluble phosphates but extended to the phospholipid and to 

 the " residual " phosphate fraction. This differential effect upon 

 various parts of the brain may offer an explanation for the finding 

 (Zamurovic et al., 1953) that intraperitoneally injected radioactive 

 phosphate is not incorporated into the whole brain of hypophy- 

 sectomized rats at a rate lower than in the normal animal. Cortico- 

 trophic hormone when administered to normal rats increased the 

 uptake of radioactive phosphate into cerebral phospholipids but 

 not into nucleoprotein nor into the total phosphate of the brain 

 (Torda, 1954). Since the radioactivity of the total brain phosphate 

 was unaffected while that of the cerebral phospholipids increased 

 some other cerebral phosphorus component presumably decreased 

 in radioactivity. 



Radiation by X-rays at 20,000 r did not affect the incorporation 

 of peripherally administered radioactive phosphate into mouse 



