To study the dynamics of pituitary prolactin secretion in RA, and its association with the HLA DR4 status in patients.
TRH stimulation of the pituitary secretion of PRL was performed in 23 RA patients and 8 control subjects, all of whom were post-menopausal women. Hormone concentrations were assessed by radioimmunoassay.
Basal prolactin concentrations were higher in RA patients compared to controls (579 +/- 80 mu UI/ml versus 187 +/- 47, (p < 0.01). An increase in the prolactin response to TRH at 30 min (2257 +/- 218 mu UI/l versus 1074 +/- 207, p < 0.005), independent of disease activity, was observed in the RA patients. In DR4+ RA patients, we observed a higher PRL peak at 60 min. (3913 +/- 506 mu UI/ml versus 2120 +/- 443, p < 0.01), and an increased residual value at 120 min compared to DR4- RA patients. The area under the curve of the PRL response was also increased in DR4+ RA patients, suggesting higher PRL secretion compared to DR4- RA patients.
In female, post-menopausal RA patients an alteration in pituitary prolactin release, not linked to disease activity, can be observed. In DR4+ RA patients, the overall prolactin secretion reflected by the AUC is increased compared to DR4- patients. These results suggest a dysregulation of the pituitary response in RA.