Expression of hexokinase 1 and hexokinase 2 in mammary tissue of nonlactating and lactating rats: Evaluation by RT-PCR

Because the initial step in the metabolism of glucose involves phosphorylat ion by hexokinase (HK), we tested the hypothesis that the expression of the isozymes, hexokinase type 1 (HK1) and hexokinase type 2 (HK2), would be di fferent in rat mammary tissue during pregnancy and lactation. RNA was extra cted from mammary tissue dissected from timed pregnant rats (from gestional days 10 to 21) and nursing rat mothers (up to postnatal day 5) for mRNA ex amination by reverse transcriptase and polymerase chain reaction (RT-PCR) u sing isozyme specific oligonucleotide primers to the HK1 and HK2 cDNAs. The HK1 mRNA was expressed in both the nonlactating and lactating mammary glan d tissue, but HK2 mRNA was found only during lactation. We speculate that t he pattern of KK expression might affect human milk production and quality. (C) 1999 Academic Press.