The L-glutamate transporters GLAST (EAAT1) and GLT-1 (EAAT2): expression and regulation in rat lactating mammary gland

The Na+-dependent L-glutamate transporters GLAST (EAAT1) and GLT-1 (EAAT2), were expressed in rat lactating mammary gland, but EAAC1 (EAAT3) was not. GLT-1 expression in rat lactating mammary gland was constant in all the phy siological situations studied; however, the GLAST expression is under tight regulation, Fasting for 24 h decreased the GLAST expression which returned to control values after refeeding. Weaning for 24 h produced a decrease in GLAST expression through a mechanism independent of prolactin deficiency. Resuckling for 6 h returned the expression of this transporter to control v alues. There is a correlation between the levels of GLAST (mRNA and protein ) and the in vivo uptake of L-glutamate by the lactating mammary gland duri ng the starvation/refeeding cycle and milk accumulation process.