Jy. Cho et al., Hormonal regulation of radioiodide uptake activity and Na+/I- symporter expression in mammary glands, J CLIN END, 85(8), 2000, pp. 2936-2943
The observation that radioiodide uptake (RAIU) activity, mediated by the Na
+/I- symporter (NIS), is significantly increased in lactating breast sugges
ts that RAIU and NIS expression in mammary gland are modulated by hormones
involved in active lactation. We showed that both the NIS expression level
and RAIU in rat mammary gland are maximal during active lactation compared
to those in the mammary glands of virgin and pregnant rats as well as the i
nvoluting mammary gland. In the lactating mammary gland, NIS is clustered o
n the basolateral membrane of alveolar cells as a lesser glycosylated form
than NIS in thyroid. The RAIU of lactating mammary gland was partially inhi
bited by treatment with a selective oxytocin antagonist or bromocriptine, a
n inhibitor of PRL release. These findings suggest that RAIU and NIS expres
sion in mammary gland are at least in part modulated by oxytocin and PRL. I
ndeed, we showed that NIS messenger ribonucleic acid level was increased in
a dose-dependent manner by oxytocin and PRL in histocultured human breast
tumors.