RESPECTIVE ROLES OF GLUCOSE AND KETONE-BODIES AS SUBSTRATES FOR CEREBRAL ENERGY-METABOLISM IN THE SUCKLING RAT

The postnatal evolution of local cerebral metabolic rates for glucose (LCM-Rglcs) and of regional rates of cerebral uptake of beta-hydroxybu tyrate (beta HB) were studied in the suckling rat between postnatal da ys (P) 10 and 21. LCM-Rglcs were low and homogeneous at P10, They incr eased significantly in 4 auditory regions between P10 and P14 at the t ime of maturation of the auditory function. Between P14 and P17, they increased further in 2 auditory regions, in I visual area, the lateral geniculate nucleus, and 3 limbic and 3 motor areas, These increases o ccurred simultaneously with the maturation of vision and with the deve lopment of the rat locomotion and behavioral activities. Between P17 a nd P21, LCMRglcs increased in all areas studied. Conversely to the fun ction-related increases in LCMRglcs, regional rates of cerebral beta H B uptake showed an overall increase between P10 and P14, stayed very h igh until P17 and did not correlate with the maturation of the rat beh avior. Between P17 and P21, rates of cerebral beta HB uptake decreased significantly in all regions studied. In conclusion, it appears that, even in the rat whose cerebral metabolic activity depends upon both g lucose and ketone bodies during suckling, postnatal increases in LCMRg lcs represent a signal of the acquisition of new functions and neurolo gical competence.