Monocarboxylate Transporter 1 in the Medial Prefrontal Cortex Developmentally Expresses in Oligodendrocytes and Associates with Neuronal Amounts.

Lactate is an energy substrate in adult brain especially when glucose is withdrawn or only lactate is present as main energy source. Besides, the most abundant lactate transporter in brain-monocarboxylate transporter 1 (MCT1)-was recognized recently. Despite this, MCT1 expressions in central nervous system (CNS) have not been clearly understood. Medial prefrontal cortex (mPFC), taking part in many higher executive functions in brain, is chosen here for observing MCT1 expressions in mice in 12 months. As results showed, MCT1 is gradually increased from an initial level at the 1st week to a high level at the 6th week and then gradually decreased to a low level at the 12th month. Besides, neuronal amounts change in a similar trend as MCT1 that neurons at the 6th week are more than that of at the 1st week and the 12th month. Also, MCT1 expressions are highly correlated with neuronal amounts, while MCT1 does not localize within neurons, instead localize around axons. On the other hand, MCT1 does localize to oligodendrocytes (OLs) without localizing to other glial cells (astrocytes and microglias). Importantly, the amounts of OLs change in a similar trend as MCT1, while the amounts of other glial cells do not change obviously in the mPFC in vivo in 12 months. These results demonstrate that the changeable expressions of MCT1 in the mPFC in vivo in 12 months may be mainly contributed by OLs and associate with the neuronal amounts. Above all, it infers that in vivo, MCT1 which is changeably expressed in OLs may further affect neuronal amounts in the mPFC in 12 months.