Effects of short and long-term lithium treatment on serum prolactin levels in patients with bipolar affective disorder. 
1.  In this study, the authors sought to test the hypothesis that Li (lithium) treatment can induce alterations in PRL (prolactin) secretion in euthymic bipolar patients compared to controls and that short and long-term administration can lead to prolactin changes different from each other.  2.  Twenty euthymic bipolar male patients on long-term lithium carbonate treatment for more than 6 months and 15 euthymic male bipolar patients on short-term Li treatment for shorter than 6 months who met DSM-IV criteria for bipolar affective disorder were included in the study.  Seventeen age-matched healthy control males were chosen among the hospital staff.  The mean +/- SD duration of Li use was 68.93+/-46.31 months in the long-term lithium-treated group and 4+/-3.42 months in the short-term lithium-treated group.  3.  Serum PRL values in the long-term Li-treated group were significantly lower than those of the control group, while there was no significant difference in PRL values between the short-term Li-treated group and the control group.  4.  Our study documents that short-term (<6 months) Li treatment does not induce any significant changes in PRL release in bipolar patients compared to normal control subjects while long-term Li treatment (>6 months) leads to lower PRL release compared to the controls.  Furthermore, PRL has wide intra-interindividual and circadian variations Li-PRL relationship seems to be very complex and probably depends on various interactions among dopamine, serotonin and PRL.  Therefore, further studies are needed to confirm the data.