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Bromocriptine suppression of TRH-stimulated prolactin and thyrotrophin release and accompanying inhibition of bromocriptine induced growth hormone release by TRH in normal man.

Six normal fasting males received on four separate occasions in random order (1) a placebo tablet followed 60 min later by 200 microgram of TRH intravenously (2) bromocriptine 2.5 mg orally followed by TRH intravenously (3) bromocriptine 2.5 mg orally followed by a placebo injection and (4) placebo tablet followed by placebo injection. Plasma prolactin and TSH responses to TRH were decreased following bromocriptine pretreatment. The rise of plasma growth hormone after bromocriptine was inhibited by TRH. The rise in plasma FSH seen after TRH injection was not influenced by bromocriptine pretreatment. Circulating LH and insulin concentrations were unaffected by any drug administration. These results suggest a dopaminergic influence on prolactin and TSH release in normal men, an inhibitory effect of TRH on bromocriptine stimulated growth hormone secretion, and no dopaminergic modulation of basal insulin secretion.

Adult

Stimulant properties of bromocriptine on central dopamine receptors in comparison to apomorphine, (+)-amphetamine and L-DOPA.

1. The activity of bromocriptine has been investigated in tests for the stimulation of central dopaminergic mechanisms. The results obtained have been compared with those of apomorphine, (+)-amphetamine and L-DOPA. 2. Bromocriptine (2.5 to 10 mg/kg) induced stereotyped sniffing and licking in rats. The stereotypy was more intense than that induced by L-DOPA and less intense than that of apomorphine and (+)-amphetamine over the dose ranges studied. 3. In rats lesioned unilaterally in the substantia nigra by local injection of 6-hydroxydopamine, bromocriptine, like apomorphine and L-DOPA, induced turning contralateral to the side of the lesion. The smallest dose of bromocriptine to induce turning was 0.5 mg/kg. 4. Reserpine-induced catalepsy in mice was antagonized by bromocriptine, with an ED50 of 1.8 mg/kg. It was intermediate in potency to apomorphine and L-DOPA. 5. Spontaneous locomotor activity in mice was stimulated by bromocriptine in a dose-dependent manner from 2.5 to 10 mg/kg after an initial suppression of activity. 6. In all experiments, bromocriptine was characterized by a prolonged duration of activity after a delay in the onset of effect. 7. The stereotyped behaviour induced by bromocriptine was inhibited by prior administration of pimozide, reserpine or alpha-methyl-p-tyrosine. 8. Bromocriptine-induced turning behaviour was abolished by pretreatment with pimozide, and reduced after alpha-methyl-p-tyrosine treatment. 9. The results obtained support the conclusion that bromocriptine acts by stimulating dopamine receptors in the central nervous system and that intact catecholamine synthesis and granular amine storage mechanisms are necessary for it to bring about its effects.

Amphetamine

Bromocriptine in Parkinsonism: long-term treatment, dose response, and comparison with levodopa.

Thirty-seven patients with Parkinsonism were treated with bromocriptine 2.5-300 mg daily. Bromocriptine, alone or combined with levodopa, caused a 20-30% reduction in disability scores in 11 patients treated for one year. Tolerance did not develop during this period. Bromocriptine treatment was not of value in six patients who had previously not responded or who had lost their response to levodopa. However, in four of five patients with response swings on levodopa due to rapid changes in plasma dopa levels, the addition of bromocriptine caused a more stable response. Dose response curves to bromocriptine 12.5, 25, 50, and 100 mg and to levodopa 250, 500, 1000, and 2000 mg were studied in seven patients. Levodopa 2 g had a greater therapeutic effect and caused a greater rise in plasma growth hormone concentration than bromocriptine 100 mg. Levodopa caused emesis more commonly and hallucinations less commonly than bromocriptine. Bromocriptine appears to be a less potent stimulant than dopamine, and has both pre- and post-synaptic effects. Metoclopramide 60 mg oral was given 30 minutes before bromocriptine or levodopa to establish whether this caused dopamine-receptor blockade. Metoclopramide acted as a competitive antagonist to the anti-Parkinsonism and growth hormone effect of both drugs and in individual cases prevented emesis and hallucinations. The fall in blood pressure due to bromocriptine or levodopa was not antagonised by metoclopramide. Central and peripheral vascular dopamine receptors may be different in nature.

Aged

Bromocriptine therapy in acromegaly.

Bromocriptine (CB-154, Sandoz) has been given to 21 acromegalic patients (11 female, 10 male) for a period of 6-10 months. The mean serum growth-hormone (G.H.) levels ranged from 10 mug/1 to 512 mug/1 before therapy. Bromocriptine suppressed G.H. values to 5 mug/1 or less in 4 patients and to less than 10 mug/1 in a further 8 patients, but in 2 patients G.H. levels did not show any significant reduction. Bromocriptine did not block stress-induced G.H. secretion. It did not distrub pituitary function other than secretion of prolactin and had negligible side-effects. Its effect on tumour size is uncertain and it is therefore unsuitable for patients with suprasellar extension of the tumour. Otherwise it seems reasonable to offer a trial of bromocriptine to all patients with acromegaly where therapy is deemed necessary. In those who show a full response of G.H. levels with a dose of 20-40 mg of bromocriptine per day, external radiation to the pituitary can be used to prevent tumour expansion and bromocriptine withdrawn at intervals to assess the effect of the radiation. In patients with a partial response to bromocriptine, the decision to offer alternative therapy depends on the extent of the response and on the age and medical condition of the patient. In patients who fail to respond to bromocriptine, particularly those younger patients with active disease, more definitive local treatment (e.g., trans-sphenoidal removal of the tumour or yttrium-90 implantation) would be indicated. Bromocriptine may also be used with benefit in the large number of patients who have shown a partial response to other forms of therapy.

11-Hydroxycorticosteroids

Plasma bromocriptine levels, clinical and growth hormone responses in Parkinsonism.

1. Plasma bromocriptine levels following separate oral doses of bromocriptine 12.5, 25, 50 and 100 mg have been determined in ten subjects with parkinsonism. 2. There was considerable variation between peak plasma bromocriptine levels in individual subjects after similar doses of bromocriptine. Peak levels occurred 30--210 min after dosage (mean 102 min). Peak clinical response, peak rise in plasma growth hormone level and fall in blood pressure followed shortly after peak bromocriptine levels occurred. 3. The shape of the plasma-time curve for bromocriptine was similar with all dosages. 4. There was no significant relationship between peak plasma bromocriptine levels, peak clinical response, peak increase in growth hormone and peak fall in blood pressure. However, the degree of improvement in the signs of parkinsonism was related to plasma bromocriptine levels was achieved. 5. Metoclopramide 60 mg pretreatment had no consistent effect upon plasma bromocriptine levels, the clinical or hormonal response.

Aged

Effect of the new dopaminergic agonist CV 205-502 on plasma prolactin levels and tumour size in bromocriptine-resistant prolactinomas.

Bromocriptine is currently and successfully used for the treatment of pituitary prolactinomas. However, bromocriptine appears unable to normalize plasma prolactin levels in about 10% and to reduce tumour size in one-third of cases. The lack of normalization of plasma prolactin levels in spite of a daily dose of bromocriptine equal to or higher than 15 mg suggests a bromocriptine resistance. We compared the long-term effects of bromocriptine and CV 205-502 (a non-ergot derivative D2 dopamine agonist) on plasma prolactin levels and tumour size in seven bromocriptine-resistant prolactinomas. Bromocriptine reduced significantly (P less than 0.001) plasma prolactin levels (from 2307 +/- 518 to 568 +/- 279 micrograms/l) (conversion to Sl units: 1 microgram/l = 20 mU/l). Visual field defects observed in five patients improved in four. However, CT scan analysis showed a decrease in tumour size in only three patients. Except for transient and minor side-effects at the beginning of the treatment, CV 205-502 was well tolerated in five of seven patients. In the remaining two patients nausea and vertigo occurred with high dosages of CV 205-502 and it was necessary to reduce the daily dose. CV 205-502 lowered plasma prolactin to levels similar to those obtained after bromocriptine therapy in four cases. In the three remaining patients, CV 205-502 was more potent than bromocriptine as demonstrated by the further 90% reduction in plasma levels obtained in one case and by the normalization of plasma prolactin levels in the two other cases. One woman became pregnant during CV 205-502 treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

Metabolic and clinical studies on patients with acromegaly treated with bromocriptine over 22 months.

In twenty-two patients with active acromegaly who were untreated or unsuccessfully operated or irradiated (mean growth hormone (GH) values greater than 4 ng/ml) the following investigations were performed: routine laboratory tests, tomography of pituitary fossa, oral glucose tolerance tests, TRH and other pituitary function tests and GH profiles over 5-10 h before and during bromocriptine treatment with daily doses between 7.5 and 50 mg. In seventeen patients GH was suppressed to less than 50% by bromocriptine, in thirteen of them it was normalized on at least one occasion. A TRH induced GH release was observed in all but two responders to bromocriptine before therapy. This effect of TRH was not blunted during treatment with bromocriptine and also in the two patients with negative tests before therapy a significant GH increase was observed. In no non-responder to bromocriptine was a significant increase of GH after TRH observed. One patient showed a secondary resistance to bromocriptine during a period of treatment with griseofulvin. In the remaining sixteen patients the GH suppression has been consistent for between 3 and 22 months. A single dose of pimozide abolished the bromocriptine effect on GH totally in one patient; in others a slight or no significant effect was observed. Tissue swelling and sweating decreased in all bromocriptine responders and glucose tolerance improved in five patients. In four diabetic patients a partial or full remission of diabetes occurred. Apart from postural hypotension after the first administration in two patients no other severe side effects have been observed. Sella size and the other pituitary functions did not change during the time of the study. It seems that a high percentage of acromegalics may be successfully treated with bromocriptine.

Acromegaly

Bromocriptine treatment in Parkinson's disease.

Thirty-one patients with Parkinson's disease were treated with the ergot alkaloid bromocriptine, a drug which stimulates dopamine receptors. Bromocriptine had a slight therapeutic effect in patients on no other treatment and an additional effect in patients on levodopa. The mean optimum dosage of bromocriptine, established over a 12 week period, was 26 mg daily. In 20 patients bromocriptine was compared with placebo in a double-blind controlled trial. Active treatment caused a significant (P less than 0.02) reduction in total disability and akinesia scores. The least disabled patients showed the greatest response. Side-effects of bromocriptine--nausea, vomiting, hallucinations, and abnormal involuntary movements--were similar to nature to those of levodopa. In most normal subjects, bromocriptine causes an increase in plasma growth hormone concentration. This was determined in 20 patients with Parkinson's disease after 1-15 mg bromocriptine. Only a single patient showed an obvious increase up to 120 minutes after dosage. Bromocriptine was not effective treatment in two patients who had not previously responded to levodopa and replacement of this drug by bromocriptine in patients with end-of-dose akinesia after chronic levodopa treatment did not totally abolish response swings.

Aged

Single dose cabergoline versus bromocriptine in inhibition of puerperal lactation: randomised, double blind, multicentre study. European Multicentre Study Group for Cabergoline in Lactation Inhibition.

OBJECTIVE: To compare the efficacy and safety of a single dose of 1 mg of cabergoline with that of bromocriptine 2.5 mg twice daily for 14 days in the inhibition of puerperal lactation. DESIGN: Prospective, randomised, double blind, parallel group, multicentre study. SETTING: University of hospital departments of obstetrics and gynaecology in different European countries. SUBJECTS: 272 puerperal women not wishing to lactate (136 randomised to each drug). INTERVENTIONS: Women randomised to cabergoline received two 0.5 mg tablets of cabergoline and one placebo tablet within 27 hours after delivery and then placebo twice daily for 14 days. Those randomised to bromocriptine received 2.5 mg of bromocriptine and two placebo tablets within 27 hours and then 2.5 mg of bromocriptine twice daily for 14 days. MAIN OUTCOME MEASURES: Success of treatment (complete or partial) according to milk secretion, breast engorgement, and breast pain; rebound symptomatology; serum prolactin concentrations; and number of adverse events. RESULTS: Complete success was achieved in 106 of 136 women randomised to cabergoline and in 94 of 136 randomised to bromocriptine and partial success in 21 and 33 women respectively. Rebound breast symptomatology occurred respectively in five and 23 women with complete success up to day 15 (p less than 0.0001). Serum prolactin concentrations dropped considerably with both drugs from day 2 to day 15; a prolactin secretion rebound effect was observed in women treated with bromocriptine. cabergoline and 36 receiving bromocriptine (p = 0.054), occurring most during the first treatment day. CONCLUSION: A single 1 mg dose of cabergoline is at least as effective as bromocriptine 2.5 mg twice daily for 14 days in preventing puerperal lactation. Because of the considerably lower rate of rebound breast activity and adverse events and the simpler administration schedule cabergoline should be the drug of choice for lactation inhibition.

Adult

Nation-wide collaborative study on the long-term effects of bromocriptine in the treatment of parkinsonian patients. Final report.

Final results of the 5-year multicentric collaborative study on the long-term effects of bromocriptine in the patients with Parkinson's disease are reported. This prospective study started in May 1985 in order to see whether the early combination therapy with bromocriptine and levodopa is really superior to the levodopa monotherapy with regard to the late side effects of levodopa in the treatment of parkinsonian patients. Another project of the study was to see the therapeutic efficacy of bromocriptine monotherapy without concomitant use of levodopa. For these purposes, a total of 702 patients with Parkinson's disease were enrolled into three groups: Group 1 (n = 286) with bromocriptine monotherapy, Group 2A (n = 216) with early combination of bromocriptine and levodopa, and Group 2B (n = 200) with levodopa alone. At the end of the 5-year study, 48 patients in Group 1 (16.8%) were still continuing bromocriptine monotherapy with satisfactorily good therapeutic effects. About half (49.1%) of the Group 2A patients remained on the combined therapy, and the comparable number of the Group 2B patients (46.0%) were also kept on the initial mode of therapy, while 13.5% of the latter group with levodopa monotherapy needed bromocriptine to be added in order to assure the good therapeutic effects. Moreover, significant differences were seen between group 2A and Group 2B with regard to the incidence of wearing-off phenomenon and dyskinesias. Disappearance rate of dyskinesias which were present at the time of enrollment was significantly higher in Group 2A than in Group 2B. No significant difference was noted as to the incidence of untoward symptoms and the death rate among all three therapeutic groups. These results support the view that the early combination of bromocriptine with levodopa is superior to levodopa alone in the treatment of Parkinson's disease.

Activities of Daily Living

Nation-wide collaborative study on the long-term effects of bromocriptine in the treatment of parkinsonian patients: analysis on the maintenance and the change of the original mode of treatment.

A nation-wide collaborative study to evaluate the long-term effects of bromocriptine in patients with Parkinson's disease was completed as described in the accompanying paper. The present study analysed the same data by paying attention to a group of patients who maintained the original mode of therapy and to a group of patients who changed the mode of treatment by adding levodopa or bromocriptine to the original drug. Surprisingly, 48 among 286 patients in a group of bromocriptine monotherapy maintained the original mode of therapy. This group has particular features of a short duration of illness and a low grade of Hoehn-Yahr's scale. It is noteworthy that this group of patients did not show wearing-off phenomenon. The effects of additional bromocriptine to levodopa for a 5-year period were analysed by comparing two groups of combination therapy and levodopa alone therapy maintained for 5 years, with 106 and 92 patients, respectively. Results were essentially the same as those obtained from the accompanying paper, i.e., in general, treatment by combination with bromocriptine may be more suitable than treatment by levodopa alone. In order to find the best timing of the combination of levodopa and bromocriptine, results of 3 groups were compared, i.e. a group of patients who started with bromocriptine alone and later added with levodopa (82 patients), a group of patients who maintained the combination for 5 years (106 patients) and a group of patients who started with levodopa alone and later added bromocriptine (27 patients). The best results were obtained in the group of 5-year combination.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living

Subsensitivity of the rat striatal dopaminergic system after treatment with bromocriptine: effects on [3H]spiperone binding and dopamine-stimulated cyclic AMP formation.

Repeated daily administration of the dopamine (DA) agonist bromocriptine (15 mg/kg; s.cut.) to rats led to a time dependent decrease in the in vitro binding of [3H]spiperone to striatal membranes. Kinetic analysis of [3H]spiperone binding after 2 and 7 days of bromocriptine treatment showed a 25-50% reduction in the total number of binding sites with no changein their affinity for spiperone. There was also a decreased accumulation of cyclic AMP (cAMP) in striatal slices in response to DA after bromocriptine treatment. The DA-sensitive adenylate cyclase in striatal homogenates, however, remained unchanged in bromocriptine treated rats. There was also no change in cyclic nucleotide phosphodiesterase activity in striatal tissue after bromocriptine treatment. Furthermore, incubation of striatal slices in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine did not alter the decreased cAMP response to DA after 2 days of bromocriptine treatment. These results suggest that a decreased number of DA receptor sites may be responsible for the reduced cAMP response to DA in striatal slices after bromocriptine treatment.

3',5'-Cyclic-AMP Phosphodiesterases

The interactions of bromocriptine and lergotrile with dopamine and alpha-adrenergic receptors.

Bromocriptine and lergotrile, which are clinically used as antiparkinsonian (AP) agents, compete for the binding of H3-dopamine, H3-apomorphine, and H3-haloperidol to striatal membrane sites. Lergotrile has a higher affinity for the H3-dopamine binding to bovine striatal membranes than bromocriptine. Lergotrile and bromocriptine are almost equipotent in competing for the binding of H3-apomorphine to rat striatal membranes, but bromocriptine is more potent in competing for the binding of H3-haloperidol than lergotrile. These results indicate that lergotrile and bromocriptine are mixed putative agonist-antagonist with respect to the postsynaptic dopamine receptors. Lergotrile and bromocriptine at higher concentrations inhibit synaptosomal tyrosine hydroxylase activity, and reverse the apomorphine elicited enzyme inhibition. Thus, these ergot alkaloids behave as mixed agonist-antagonist also with respect to the presynaptic dopamine receptors. Bromocriptine and lergotrile, as well as other tested DH-ergot alkaloids and neuroleptics, compete for the binding of the alpha-antagonist H3-WB-4101 to rat cerebral cortical membranes. The displacing potencies of the tested DH-ergot alkaloids and of the neuroleptics indicate that they have a high affinity for the alpha-adrenoreceptors in the CNS.

Acetonitriles

Long-term treatment of parkinsonism with bromocriptine.

92 patients with parkinsonism have been treated with bromocriptine for up to 30 months. 48 continue to receive bromocriptine with benefit; of these, 35 take bromocriptine (mean dose 53 mg daily) in combination with levodopa and 13 take bromocriptine (mean dose 45 mg daily) without levodopa. In those who were originally on levodopa, addition of bromocriptine allowed a mean 41% reduction in the dose of levodopa; the largest group of patients to benefit from bromocriptine entered the study because of excessive dyskinesia or "on-off" phenomena induced by levodopa. In 40 patients bromocriptine was stopped because of adverse reactions, absence of therapeutic response, or non-compliance with the protocol. The main problems were psychiatric disturbance (8 patients) and erythromelalgia (7 patients); these effects tended to occur late (mean 6 months and 10 months, respectively) and with high dosage (mean 66 mg and 115 mg daily). Other frequent adverse effects were dizziness and nausea; these began considerably earlier (at 2 months and 1 month) and with much lower dosage (31 mg and 12 mg daily). 4 patients died, for reasons apparently unrelated to therapy.

Bromocriptine

Bromocriptine treatment of oligospermia: a double blind study.

A double blind controlled study of bromocriptine treatment of oligospermia was carried out. Out of fifty-one men who originally volunteered to the study there were forty who took the drug for 12 weeks as requested. All the partners of these men had failed to conceive, and in each case the pretreatment sperm count had been below 40 million/ml on two or several occasions. The pretreatment serum prolactin concentrations were similar in patients given bromocriptine (N = 20) and placebo (N = 20). There were three men in either group whose pretreatment serum prolactin concentration was in excess of 30 micrograms/l, the highest value being 96 micrograms/l. While bromocriptine effectively decreased the serum prolactin concentration, it had no significant effect over placebo on sperm volume, motility and morphology. In the bromocriptine group, sperm count increased to or above 40 million/ml in five out of twenty men, while in the placebo group this occurred in nine out of twenty patients. The plasma testosterone and dihydrotestosterone levels increased slightly during treatment in both groups, but no significant difference was observed between bromocriptine and placebo treated patients. One wife of a bromocriptine-treated man and two wives of placebo-treated men became pregnant during treatment. In this study bromocriptine was no more effective than placebo in the treatment of oligospermia.

Adult

Differential inhibition of dopamine and bromocriptine on induced prolactin release: multiple sites for the inhibition of dopamine.

Effects of dopamine and bromocriptine on TRH- or dibutyryladenosine 3',5'-cyclic monophosphate (dbcAMP)-induced prolactin release from primary cultured rat pituitary cells were studied using a perifusion system. TRH (100 nmol/l) stimulated prolactin release from basal concentrations of 33.8 +/- 0.5 to 151.2 +/- 28.0 ng/ml (net increase) or 447% increase. Dopamine inhibited the basal release of prolactin throughout the experiment, but TRH (100 nmol/l) was still able to stimulate prolactin release under the influence of dopamine. The increment in prolactin release was inversely proportional to the dopamine concentration. When TRH (100 nmol/l) was introduced during a perifusion period with bromocriptine 1 nmol/l, the prolactin concentration was increased to 110.9% of basal levels. The stimulatory effect of TRH under the influence of bromocriptine (1 nmol/l) was significantly lower than that without bromocriptine (control), although the higher concentrations of bromocriptine (10 and 100 nmol/l) did not further reduce the peak concentration of TRH-induced prolactin release. During a perifusion period with a low concentration of dopamine (1 nmol/l plus 0.1 mmol/l ascorbic acid), introduction of dbcAMP (3 mmol/l) stimulated prolactin release to 48% of basal concentration. A higher concentration of dopamine further reduced the stimulatory effect of prolactin release. Bromocriptine impeded the stimulatory effect of dbcAMP (3 mmol/l) on prolactin release in a similar manner as dopamine. Since a higher concentration of bromocriptine (10 and 100 nmol/l) did not further inhibit the TRH-induced prolactin release whereas a higher concentration of dopamine did, it is concluded that dopamine acts through additional mechanism(s) other than the D2 receptor transduction system.

Animals

Bromocriptine inhibits pro-opiomelanocortin mRNA and ACTH precursor secretion in small cell lung cancer cell lines.

We have previously reported that a human small cell lung cancer (SCLC) cell line (COR L103) that expresses the proopiomelanocortin (POMC) gene and secretes ACTH precursor peptides is relatively resistant to glucocorticoid regulation. Using this model, we have now examined alternative regulatory mechanisms of the POMC gene and found that both the mRNA and ACTH precursor peptides were stimulated four- and two-fold, respectively, after 48 h incubation with db-cAMP. Next, we examined the dopamine agonist, bromocriptine, which acts predominantly through D2 receptors linked to adenyl cyclase to cause a reduction in intracellular cAMP. Bromocriptine suppressed cAMP levels and inhibited precursor peptide secretion within 24 h in a dose-dependent manner (0.15-15 microM). At the highest dose, peptide secretion was inhibited from 95 to 53 pmol/mg protein, and POMC mRNA was reduced by 50%, while beta-actin mRNA remained unchanged. This effect could not be mimicked by incubation of cells with the alpha-adrenergic antagonist, phenoxybenzamine, suggesting that the alpha-adrenergic effects of bromocriptine were not responsible for this observation. These cells also secrete estradiol, but the secretory rate was unaffected by bromocriptine, suggesting, with the beta-actin data, that the POMC inhibition was not a cytotoxic effect. No recovery in precursor peptide secretion was seen in a 48-h period after the removal of bromocriptine. However, when the postchallenge incubation was extended to 8 d, there was a recovery in secretory potential between day 3 and day 8 and normal growth kinetics in the 4 d after removal of the drug. In contrast to these findings, the mouse corticotroph cell line, AtT20, showed no response to bromocriptine, in keeping with reports that this agonist has no effect on anterior lobe corticotrophs. We conclude that bromocriptine effectively inhibits POMC expression in SCLC cells, and that this phenomenon might be of useful clinical application.

Adrenocorticotropic Hormone

Prolactin and thyrotropin responses to thyrotropin-releasing hormone in patients with secondary amenorrhea: the effect of bromocriptine.

Prolactin (PRL) and thyrotropin (TSH) responses to a 200 mug intravenous thyrotropin-releasing hormone (TRH) bolus were measured by radioimmunoassay in 11 women with hyperprolactinemic amenorrhea and 9 with normoprolactinemic amenorrhea. In all cases, the tests were carried out under basal conditions and repeated during bromocriptine treatment. In women whose basal PRL level was normal; TRH caused a maximal PRL increment of 85 +/- 25.2 mug/l (mean +/- SE), while those women whose basal PRL level was raised showed a smaller increase (5.2 +/- 11.9 mug/l) (P=0.02). The peak levels were not significantly different in these two groups (95.0 +/- 26.7 and 134.6 +/- 35.9 mug/l) (P is greater than 0.1). During bromocriptine treatment, the raised PRL levels decreased in all cases, but levels over 30 mug/l remained in 3 patients, one of whom turned out to have a pituitary tumor. Prolactin responses to TRH were markedly inhibited in normoprolactinemic patients by the dose of bromocriptine used. The mean maximal net increase of PRL was 2.0 +/- 0.9 mug/l in normoprolactinemic patients and 11.0 +/- 8.1 mug/l in hyperprolactinemic patients taking bromocriptine. After TRH stimulation during bromocriptine, the peak PRL levels in hyperprolactinemic patients were higher (32.7 +/- 10.5 mug/l) than in normoprolactinemic patients (7.2 +/- 1.5 mug/l). Unlike what has been described for hypothyroid patients, the basal TSH level in euthyroid amenorrhea patients was not affected by bromocriptine, and we found that bromocriptine has no effect on the TRH-TSH response.

Adult