A first-trimester serum TSH in the 4-10 mIU/L range is associated with obstetric complications in thyroid peroxidase antibody-negative women

PURPOSE

The impact of mild subclinical hypothyroidism on pregnancy outcomes in TPOAb-negative women is poorly explored. The aim of the present study was the evaluation in a wide cohort of TPOAb-negative pregnant women the role of subclinical hypothyroidism (SCH) on several pregnancy outcomes.

METHODS

The study included women aged ≥ 18 years with a singleton pregnancy without known thyroid disease with serum TSH concentration between 0.4 and 10 mIU/L and TPOAb negative. Data about clinical and demographic features were collected. A blood sample was drown to test TSH, TPOAb, ANA and ENA concentration. The mean uterine artery pulsatility index was measured. Risk of adverse obstetric and fetal outcomes was collected.

RESULTS

The cohort included 2135 pregnant women. Pregnant women with TSH 4-10 mUI/L had a significantly higher frequency of family history of thyroid diseases, and personal history of celiac disease diseases, type 1 diabetes mellitus, rheumatic disease, antinuclear antibody (ANA) and anti-extractable nuclear antigen (ENA) positive tests. The risk for pre-eclampsia and small for gestational age (SGA) was significantly higher in pregnant women with first-trimester TSH 4-10 mIU/L. A first-trimester TSH serum level greater than 4 mIU/L was associated with a significant increase in the occurrence of abnormal uterine artery pulsatility index, with a more than threefold increase in the risk of developing pre-eclampsia and with the risk of SGA.

CONCLUSIONS

In TPOAb-negative pregnant women, a first-trimester serum TSH level ranging from 4 to 10 mIU/L is significantly and independently linked to an increased uterine artery pulsatility index as well as to negative pregnancy outcomes such as pre-eclampsia, SGA and gestational diabetes.

POS0924 THE ROLE OF RAYNAUD’S PHENOMENON ON MATERNAL AND FETAL OBSTETRICAL OUTCOMES

Background

It is established that Raynaud’s phenomenon (RP) may influence pregnancy outcomes when secondary to rheumatic conditions (1,2). Data on the impact of primary RP (pRP) on pregnancy are very limited.

Objectives

To retrospectively evaluate the impact of pRP on pregnancy outcomes.

Methods

Women with pRP were included in the study. They were compared with a group of women affected by UCTD with RP, and by UCTD without RP. These women were assessed and followed at our outpatient clinic from January 2011 to October 2020 and they did not exhibit an evolution to a UCTD or to a definite CTD during at least one-year follow-up. Antiphospholipid antibody positivity, twin pregnancies and voluntary termination of pregnancy were exclusion criteria. Women with pRP were also compared with a group of healthy pregnant women enrolled by our gynaecologist during the first trimester of pregnancy. Maternal and foetal outcomes were retrospectively recorded. ANOVA or the Kruskal-Wallis test for continuous variables, and the Chi2 test or the Fischer exact test for categorical were performed (level of significance. P<0.050). In the post-hoc analysis we used the Mann-Whitney test (quantitative variables) or with the Chi2 test/Fischer exact test (qualitative variables), applying the Bonferroni correction with pRP women as a reference group (level of significance: p<0.0167).

Results

The analysis included 188 women with a total of 375 pregnancies divided in 4 groups:

-Group “pRP”: 46 women with RP without secondary causes, and a total of 106 pregnancies (reference group),

-Group “RP-UCTD”: 48 UCTD women with RP and a total of 88 pregnancies,

-Group “UCTD”: 37 UCTD women without RP and a total of 88 pregnancies,

-Group “HC”: 57 healthy women with a total of 93 pregnancies.

The reference group did not differ from the others regarding age at conception.

Prophylactic acetylsalicylic acid was administered during pregnancy to 9% of patients with pRP compared to 1% in HC (p=0.010). In contrast, in the RP-UCTD this percentage was significantly higher (32%, p<0,001) than in pRP.

pRP group showed an increased rate of 1st trimester miscarriages (33% vs 16%, p=0.006, OR 2.05 and 95%CI 1.05-3.98), a lower median birth weights (3038 g vs 3358 g, p=0.002), a higher rate of infants with a birth weight <10th percentile (21% vs 3%, p=<0.001, OR 8.36 and 95% CI 1.85 - 37.84) with respect to HC. There was no statistically significant difference between the reference and the UCTD groups.

No statistically significant differences were observed when considering obstetrical outcomes (eg: mode of delivery, median gestation duration, gestational diabetes mellitus, hypertensive disorder of pregnancy, premature rupture of membranes, oligo-anhydramnios).

Conclusion

Our study shows that pRP in a retrospective cohort has an impact on pregnancy outcomes, with significantly more miscarriages and lower birth weight infants compared to HC. Importantly, pregnancy outcome in pRP women did not differ with respect to UCTD with and without RP, conditions generally associated to maternal morbidity, but in the RP-UCTD group prophylactic acetylsalicylic acid was more commonly prescribed.

Further prospective studies aiming at evaluating these differences and at identifying the appropriate follow-up and the possible benefit from the use of prophylactic acetylsalicylic acid during pregnancy in RP are necessary.

References

[1]Liu E et al. Arch Rheumatol., 2017.

[2]Al Arfaj A et al. Lupus. 2010.

Table 1.

Analysis of obstetrical outcomes

Primary RP (pRP)RP-UCTDUCTDHCp-valueMiscarriagesN. (%)35 (33%)17 (19%)30 (31%)15 (16%)p=0,017vs pRPreferencep=0,051p=0,750p=0,006Median weight at birth(IQR), gr3038 (2710-3500)3180 (2935 - 3465)3157 (2910 - 3610)3358 (3195 - 3583)p=0,02vs pRPreferencep=0,3473p=0,1542p=0,0002Birthweight < 10th percentileN. (%)15 (21%)7 (10%)5 (8%)2 (3%)p=0,002vs pRPreferencep=0,087p=0,03p=<0,001

Disclosure of Interests

None declared

SAT0280 IMPACT OF PLACENTAL FACTORS ON PREGNANCY AND FETAL OUTCOME IN SYSTEMIC SCLEROSIS

Background:

Systemic Sclerosis (SSc) is one of the rheumatic diseases burdened with obstetrical complications. An Italian multicenter study showed that women with SSc have a higher-than-normal risk of intrauterine growth restriction, preterm delivery, very-low birth weight babies and pregnancy should be discouraged in patients with severe organ damage. However, with a multidisciplinary management, patients with SSc can have successful outcomes1. Little is known about the pathogenesis of obstetrical complications, as studies on placenta are case reports or description of a few cases2,3.

Objectives:

The aim of this study was to analyze the placental alterations with a focus on the role of inflammation in the pathogenesis of obstetrical complications in SSc, including the study of the atypical chemokine receptor 2 (ACKR2), involved in immune modulation and known to be highly expressed in circulating leucocytes in SSc patients4-6.

Methods:

Eight SSc pregnant patients were compared with 16 patients with other rheumatic diseases (ORD) and 16 healthy controls (HC), matched for gestational age. Clinical data were collected. Placentas biopsies were obtained for histopathological analysis and immunohistochemistry for CD3, CD20, CD11c, CD68 and ACKR2. Frozen placenta samples from 4 SSc, 8 ORD and 8 HC were analyzed by qPCR for ACKR2 gene expression and proteins were extracted for multiplex assay for cytokines, chemokines and growth factors involved in angiogenesis and inflammation. Statistical analysis was performed with parametric or non-parametric tests depending on samples distribution.

Results:

The number of placental CD3 (p<0.05), CD68 (p<0.001) and CD11c+ (p<0.001) cells was significantly higher considering the group of patients affected by rheumatic diseases (SSc+ORD) compared to HC. The SSc group alone did not show significance due to the lower sample size. No differences were observed between groups in terms of vascular alterations or fibrosis. The percentage of stained area for ACKR2 and the ACKR2 transcripts levels were comparable between groups. Hepatocyte growth factor (HGF), involved in angiogenesis, was significantly increased in the group of rheumatic diseases patients (SSc+ORD) compared to HC (p<0.05), while the chemokine CCL5 was significantly higher in SSc patients compared to patients affected by ORD (p<0.05) and to HC (p<0.01). CCL5 levels directly correlated with the number of all inflammatory cells considered and higher levels were associated to histological villitis (p<0.01).

Conclusion:

The higher number of placental inflammatory cells and the alterations in the levels of HGF and especially CCL5 could play a role in the pathogenesis of the obstetrical complications in SSc. ACKR2 does not seem involved in the obstetrical complications of SSc.

References:

[1]Taraborelli M, et al. Arthritis Rheum. 2012

[2]Ibba-Manneschi L, et al. Ann Rheum Dis. 2010

[3]Doss BJ, et al. Hum Pathol. 1998

[4]Graham GJ. Eur J Immunol. 2009

[5]Martinez de la Torre Y, et al. Proc Natl Acad Sci U S A. 2007

[6]Codullo V, et al. Ann Rheum Dis. 2011

Disclosure of Interests:

None declared

Gonadal and uterine function in female survivors treated by chemotherapy, radiotherapy, and/or bone marrow transplantation for childhood malignant and non-malignant diseases

OBJECTIVE

To evaluate gonadal function and uterine volume in a cohort of female survivors treated by chemotherapy, radiotherapy, and/or stem cell transplantation (SCT) for childhood malignant and non-malignant diseases.

DESIGN

An observational study.

SETTING

S. Matteo Hospital, Pavia, Italy.

POPULATION

A cohort of 135 female survivors.

METHODS

A clinical, hormonal, and ultrasonographic evaluation. Thirty-three patients (24%) had non-malignant haematologic diseases (thalassaemia or sickle cell anaemia), 68 (50%) had leukaemia, 23 (17%) had lymphomas, and 11 (8%) had solid tumours. In total, 106 patients had received SCT, preceded by a conditioning regimen.

MAIN OUTCOME MEASURES

Anti-Müllerian hormone (AMH) and Inhibin-B, and uterine volume.

RESULTS

The median concentrations of AMH and Inhibin-B in the entire cohort were 0.12 ng/ml (interquartile range, IQR, 0.1-0.5 ng/ml) and 3.5 pg/ml (IQR 0.1-13.2 pg/ml), respectively. In a stepwise ordered logistic regression analysis, conventional chemotherapy for the treatment of malignancies, as opposed to total body irradiation (TBI), was the only oncologically significant predictor of increased AMH levels (OR 4.8, 95% CI 1.9-12, P < 0.001). Conditioning treatment before or after menarche did not influence AMH concentrations (P = 0.24). The best predictor of reduced uterine volume was TBI during the preparation for the allograft (OR 3.5, 95% CI 1.4-8.4, P = 0.006). Increasing age at treatment (OR 0.86, 95% CI 0.77-0.95, P = 0.04), chemotherapy, as opposed to other treatments (OR 0.09, 95% CI 0.03-0.28, P < 0.001), and solid tumours as opposed to either leukaemia/lymphomas or non-malignant diseases (OR 0.2, 95% CI 0.07-0.56, P = 0.002) were associated with larger uterine volumes.

CONCLUSIONS

Conditioning therapies for SCT, including TBI, had the worst effects on uterine volume and gonadal reserve. Increasing age at treatment and conventional chemotherapy were associated with less detrimental effects on uterine volume.

Effects of uncomplicated vaginal delivery and epidural analgesia on fetal arterial acid-base parameters at birth in gestational diabetes

AIM

To investigate the effects of uncomplicated vaginal delivery and epidural analgesia on fetal acid-base parameters in women with gestational diabetes (GDM) compared with controls.

METHODS

A retrospective case-control study of 142 women with gestational diabetes and 284 controls. To evaluate the effect of diabetes and analgesia on acid-base status correcting for potential confounders we used ordered logistic equations including quartiles of fetal arterial acid-base parameters collected at birth as outcomes and categories of diabetes and epidural analgesia as explanatory variables.

RESULTS

In the GDM group cord base deficit (-2.63 mmol/l, interquartile range [IQR]=4.2 to -0.65 mmol/l vs. -1.9 mmol/l, IQR=-3.3 to -0.2 mmol/l, p=0.009, odds ratio (OR)=1.51, 95% confidence interval (CI)=1.04-2.18) was lower and concentration of calcium higher (1.49 mmol/l, IQR=1.42-1.56 mmol/l vs. 1.47 mmol/l, IQR=1.41-1.51 mmol/l, p=0.009, OR=1.69, 95% CI=1.12-2.56) compared with controls. Epidural analgesia in the GDM group was associated with reduced cord concentration of glucose (84.0mg/dl [4.7 mmol/l], IQR=70-103.3mg/dl vs. 92.5mg/dl [5.1 mmol/l], IQR=76.5-121.8 mg/dl, p=0.004), lactate (2.65 mmol/l (IQR=1.80-4.20) vs. 3.70 mmol/l (IQR=2.90-5.55 mmol/l), p=0.002) and less pronounced base deficit (-2.05 mmol/l, IQR=-3.90 to -0.17 mmol/l vs. -2.8, IQR=-5.57 to -1.05 mmol/l, p=0.01, OR=0.7, 95% CI=0.49-0.99).

CONCLUSIONS

In uncomplicated pregnancies and deliveries, well-controlled gestational diabetes mellitus has potentially significant detrimental effects on fetal acid-base status at birth. Epidural analgesia reduces cord arterial glucose and lactates.

Utility of breast ultrasonography in the diagnostic work-up of precocious puberty and proposal of a prognostic index for identifying girls with rapidly progressive central precocious puberty

OBJECTIVE

To determine the utility of breast ultrasono- graphy in the diagnostic work-up of precocious puberty and to create a prognostic index for early differentiation between non/slowly progressive or transient forms of precocious puberty and rapidly progressive central precocious puberty.

METHODS

We recruited consecutively 60 girls with precocious pubertal development. In all the girls we evaluated Tanner stage, basal and gonadotropin-releasing hormone (GnRH)-stimulated follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels, estradiol (E2) levels, and bone age, and performed pelvis and breast ultrasound examinations. Logistic regression models were fitted to identify possible diagnostic factors for rapidly progressive central precocious puberty and non/slowly progressive or transient forms.

RESULTS

Ultrasound breast volume>or=0.85 cm3 was associated with rapidly progressive central precocious puberty (P=0.01). Uterine volume>or=5 cm3, LH peak>or=7 IU/L, presence of an endometrial echo, E2 levels>or=50 pmol/L and bone age>2 SD above expected were significantly associated with rapidly progressive central precocious puberty. A multivariate model including uterine volume, E2 level, bone age, presence of an endometrial echo and ultrasound breast volume revealed a strong ability to classify rapidly progressive forms. From this multivariate analysis a prognostic index for rapidly progressive central precocious puberty was defined.

CONCLUSIONS

Ultrasound imaging allows better definition of the breast and the maturation stage than does use of Tanner's stages. Ultrasound breast volume>or=0.85 cm3 is an independent predicting factor of rapidly progressive central precocious puberty. A prognostic index that was created from a multivariate model including uterine volume, E2 level, presence of an endometrial echo, bone age and ultrasonographically determined breast volume, may help in the early differentiation between rapidly progressive central precocious puberty and non/slowly progressive or transient forms.

Prevalence of undiagnosed autoimmune rheumatic diseases in the first trimester of pregnancy. Results of a two-steps strategy using a self-administered questionnaire and autoantibody testing

OBJECTIVE

To evaluate the prevalence of undiagnosed rheumatic diseases in the first trimester of pregnancy.

DESIGN

We screened for rheumatic diseases in 1210 consecutive pregnant women during the first trimester of pregnancy using a 10-item questionnaire.

SETTING

A university hospital in northern Italy.

POPULATION

One hundred and thirty-seven (11.3%) women who answered positively to at least one question constituted the cases and were compared with 107 negative controls.

METHODS

Cases and controls were tested for rheumatic autoantibodies (antinuclear antibody, anti-double-stranded DNA, anti-extractable nuclear antigen, anticardiolipin antibody, anti-beta2-glycoprotein I antibodies and lupus anticoagulant) and were evaluated by a rheumatologist for a definite diagnosis of rheumatic disease.

MAIN OUTCOME MEASURES

Prevalence of undiagnosed rheumatic disease in the first trimester of pregnancy.

RESULTS

The overall rate of positivity to the antibodies tested was 43.1% (59/137) among cases and 9.3% (10/107) in the controls (P < 0.001). A definitive diagnosis of rheumatic disease was made in 35 cases (25.5%) and in none of the controls (P <0.001). In stepwise logistic regression analysis, photosensitivity (adjusted OR 5.72; 95% CI 2.38-13.8), erythema or malar rash (adjusted OR 3.91; 95% CI 1.53-10) and history of two or more miscarriages (adjusted OR 5.6; 95% CI 1.55-20.6) were independent predictors of a definitive diagnosis of rheumatic disease (area under receiving operator curve = 0.814; 95% CI 0.76-0.86). Birthweight was lower (3180 g +/- 475 compared with 3340 g +/- 452, P= 0.008), and overall serious pregnancy complications (miscarriage, fetal growth restriction, delivery before 34 weeks of pregnancy and severe pre-eclampsia) were higher among cases (12/137) than controls (2/107) (adjusted OR 5.60; 95% CI 1.29-24.3; P= 0.021).

CONCLUSIONS

A two-step screening process with a self-administered questionnaire proved to be a useful method to screen for undiagnosed rheumatic diseases during the first trimester of pregnancy.

Ultrasonography endometrial patterns in different hormonal treatments to induce ovulation

As several studies report that transvaginal ultrasound of endometrial thickness may help distinguish fertile from infertile cycles, we assessed endometrial growth and morphology in 124 infertile women. The patients underwent different ovulation induction treatments: clomiphene citrate (CC), human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG), analogous Gn-RH and hMG (aGn-RH+hMG). CC administration is followed by a slackening of endometrial maturation. The US pattern H (typical of the ovulatory phase) appears on day 13 (76.9% of the cases) in spontaneous cycles and on day 16 (75% of the cases) in CC-induced cycles. The H pattern on day 20 in CC-induced cycles persisted in the patients who did not conceive. In aGn-RH-stimulated cycles the endometrial pattern H appears on days 13 (41.66%) and 16 (83.33%), not preceded by a Hi image. The endometrial pattern Hi was always observed in the patients who did not conceive. Our retrospective study of endometrial US morphology shows that the different ovulation induction treatments may affect the day of appearance of the various endometrial patterns. These results, which need further confirmation, can allow the changes of conceiving to be investigated during the stimulation protocol of every single stimulated cycle.

[Combined use of goserelin acetate and human menopausal gonadotropin in the induction of follicular growth in a program of fertilization in vitro and embryo transfer]

OBJECTIVE

to investigate the efficacy of a gonadotropin-releasing hormone analogue (GN-RH-a) in combination with human menopausal menotropin (hMG) for in-vitro fertilization.

METHODS

30 infertile women aged 32 to 37 years received a combined treatment with a long-acting slow-releasing Gn-RH-a and hMG to perform ovarian stimulation in a program of in-vitro fertilization. Serum levels of Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), 17-beta-estradiol (E2), Progesterone (P), were evaluated and transvaginal ultrasonographic examinations were performed during the treatment to assess the ovarian volume, the mean number and diameter of growing follicles and the endometrial morphology and thickness. Oocyte retrieval was performed by transvaginal-ultrasound-guided approach, 24-36 hours after the administration of human chorionic gonadotropin (hCG).

RESULTS

our data suggest that the combined use of Gn-RH-a and exogenous gonadotropins is associated with a more uniform ovarian response and with the absence of premature LH discharge. Moreover, the Gn-RH-a as polymer implant provides a controlled delivery per day over a one-month period and avoids the inconvenience of a daily administration.

CONCLUSIONS

this kind of Gn-RH-a formulation, in in-vitro fertilization programs, appears very effective in inducing a reversible hypogonadic state, easy to manage and well tolerated by the patient. Its association with exogenous gonadotropins appears to be effective in increasing the success rate of good quality oocyte retrieval.

Prevention of puerperal lactation by a single oral administration of the new prolactin-inhibiting drug, cabergoline

To evaluate the efficacy of a single oral administration of the new ergot derivative Cabergoline in the prevention of post-partum lactation, we compared the effects of three different doses of the drug with those of placebo in 32 puerperal women. In a controlled, double-blind trial, the subjects were randomly allocated to four treatment groups receiving either placebo or 400, 600, or 800 micrograms Cabergoline (N = 8 in each group) within 24 hours after delivery. Treatment efficacy was assessed clinically by physical examination before (day 0) and at one, two, three, four, and 14 days after treatment. Plasma prolactin (PRL) concentrations were measured in blood samples collected before and at one, two, three, and four days after treatment. Lactation was prevented in four of the eight subjects (50%) who received 400 micrograms Cabergoline and in all subjects who received 600 or 800 micrograms Cabergoline. By contrast, only one of the eight subjects (12.5%) receiving placebo showed no signs of spontaneous lactation within the 14 days after delivery. No effects of placebo administration on plasma PRL levels were observed. Plasma PRL concentrations were significantly reduced starting from one day after Cabergoline administration, however, and the amount of inhibition of PRL secretion induced by different doses of the drug was not statistically different. These preliminary data demonstrate that Cabergoline has a dose-related effect in the prevention of postpartum lactation, and milk secretion can be prevented completely by a single oral administration of 600 or 800 micrograms of the drug.

Dose-related prolactin inhibitory effect of the new long-acting dopamine receptor agonist cabergoline in normal cycling, puerperal, and hyperprolactinemic women

Two different single doses (400 and 600 micrograms) of the new long-acting dopamine agonist cabergoline (CBG) were given to 12 normal cycling women, 17 puerperal women, and 24 hyperprolactinemic women (12 with idiopathic hyperprolactinemia and 12 with pituitary adenoma). Plasma PRL was determined in blood samples collected before and at frequent intervals for 5 days after CBG administration. Both CBG doses induced marked inhibition of PRL secretion in all women. A decrease in plasma PRL levels was evident 1-2 h after CBG administration and persisted for up to 5 days. The 600-micrograms CBG dose had a more potent (P less than 0.05) PRL inhibitory effect than the 400-micrograms dose in normal, puerperal, and hyperprolactinemic women. Moreover, while 400 micrograms CBG prevented lactation in 3 of 7 puerperal women, 600 micrograms CBG prevented lactation in 5 of 5 puerperal women. A moderate blood pressure decrease occurred 3-6 h after CBG treatment, but no other side-effects occurred. These results demonstrate that CBG induces a dose-related inhibition of PRL secretion in normal women as well as in puerperal and hyperprolactinemic women. The potent long-lasting PRL inhibitory effect of CBG in conjunction with the absence of side-effects typical of dopaminergic compounds suggest that this drug is an advance in the medical treatment of hyperprolactinemia.

Involvement of endogenous gabaergic system in the modulation of gonadotropin secretion in normal cycling women

To investigate whether endogenous GABA participates in the control of gonadotropin secretion during the menstrual cycle, placebo or sodium valproate (DPA), an anticonvulsant drug which enhances endogenous GABA content by blocking GABA degradation, were administered to regularly cycling women both during early follicular and midluteal phase. In a first set of experiments, the effect of DPA administration (400 mg, orally) on basal gonadotropin secretion was evaluated in 13 subjects. During early follicular phase (n = 6), no significant changes in plasma gonadotropin levels were observed after DPA or placebo administration. Conversely, during midluteal phase (n = 7), DPA administration resulted in a significant fall (p less than 0.01) in plasma LH concentrations, with a maximal percent decrease of 41.8 +/- 6.7% after 120 min. No changes in plasma FSH levels were observed. In a second set of experiments, the effect of DPA pretreatment (400 mg, orally) on gonadotropin release stimulated by a pulse of exogenous GnRH (10 micrograms, iv bolus) was studied in 11 subjects. During both follicular (n = 4) and luteal phase (n = 7), DPA did not modify gonadotropin response to GnRH injected 1h after pretreatment. Finally, 8 subjects were submitted to iv injection with 10 micrograms GnRH 2h after pretreatment with DPA (400 mg, orally) or placebo. During both follicular (n = 4) and luteal phase (n = 4), no statistical differences in gonadotropin response to GnRH were found between DPA and placebo pretreatment. These findings demonstrated that during the estrogen-progesterone (midluteal) phase of menstrual cycle, endogenous GABA is involved in the inhibitory regulation of LH secretion at a central level.

Effects of the GABAergic drug, sodium valproate, on the prolactin release evoked by pharmacological stimuli in normal women

Sodium valproate (DPA or Na-dipropylacetate), an anticonvulsant drug activating the endogenous GABAergic system, was administered orally at the dose of 400 mg to seventeen normal women 1 h before intravenous injections with three drugs which stimulate prolactin (PRL) release: TRH (200 micrograms bolus; six subjects); domperidone (5 mg bolus; six subjects); and sulpiride (5 mg bolus; five subjects). DPA pretreatment significantly blunted PRL response to both domperidone and sulpiride injections without affecting the PRL response to TRH. In particular, the quantitative PRL secretion (areas under curves) following domperidone and sulpiride tests appeared significantly reduced after DPA treatment in comparison to placebo (P less than 0.02 and P less than 0.01 for domperidone and sulpiride respectively). These results indicate that the pharmacological enhancement of the endogenous GABAergic system by DPA may blunt PRL response to both central and peripheral dopamine receptor blockade. These observations suggest that a GABAergic pathway inhibiting PRL secretion at the hypothalamic level competes, at least in part, with the dopaminergic system. Conversely, the lack of any effect of DPA on PRL response to TRH seems to suggest that pituitary TRH receptors are independent of any GABAergic control.