0021-972X/78/4701-0018$02.00/0 Journal of Clinical Endocrinology and Metabolism Copyright © 1978 by The Endocrine Society
Vol. 47, No. 1 Printed in U.S.A.
Effect of Parathyroid Hormone on Plasma Prolactin in Man ROLAND ISAAC, ROBERT E. MERCERON, GENEVlfiVE CAILLENS, JEAN-PAUL RAYMOND, AND RAYMOND ARDAILLOU Service d'Explorations Fonctionnelles and Unite de Recherches INSERM 64 (R.I., G.C., R.A.), Hbpital Tenon, 75020 Paris, France; and Service d'Endocrinologie (R.E.M., J.-P.R.), Hbpital Beaujon, 92110 Clichy, France ABSTRACT. The iv infusion of parathyroid extract or the synthetic fragments of 1-34 bovine or human parathyroid hormone produced a rapid and marked increase of plasma PRL in normal subjects. The stimulation of the release of endogenous parathyroid hormone by administration of disodium EDTA also resulted in a parallel increase of plasma PRL. Parathyroid hormone did not act via plasma cAMP, as the plasma level reached by this nucleotide was too small to produce PRL release.
The ingestion of L-dopa 2 h before parathyroid hormone infusion suppressed the PRL response, suggesting that dopamine and parathyroid hormone interact at a common site. As it has been recently shown that PRL stimulates the renal synthesis of 1,25-dihydroxycholecalciferol, the present data suggest that the effect of parathyroid hormone on this synthesis may be due to the increase in plasma PRL. (J Clin Endocrinol Metab 47: 18, 1978)
T
a brachial vein and 5% glucose or 0.9% saline, according to the protocol, was administered iv through a catheter positioned in the opposite arm for at least 30 min before the first blood collection. The subjects were divided into five groups, each corresponding to a different study protocol.
HE secretion of several anterior pituitary hormones is influenced by a variety of factors including the intracellular concentration of calcium (1) and cAMP (2, 3). As the increase of these two parameters is the main cellular effect of parathyroid hormone [PTH (4)], we decided to study the role of an increase in plasma PTH on the plasma concentration of some anterior pituitary hormones. Although the anterior hypophysis has never been demonstrated as a site for PTH specific receptors, a clear-cut increase in plasma PRL was observed which is reported in the present study.
Group 1 (two men and one woman, 22-38 yr old) Parathyroid extract (450 USP; Eli Lilly and Co., Indianapolis, IN.) was administered iv over 1 h in 5% glucose containing 2% human serum albumin at 0.75 ml/min. The control solution without PTH was infused at the same rate during the hour preceding and the hour after PTH administration. Blood samples were taken every 30 min during the control periods and every 15 min during the administration of PTH.
Materials and Methods Fifteen normal volunteers (eight men and seven women) ranging in age from 22-38 yr were studied. All were within 5% of their ideal body weight and had not ingested any medications for at least 2 weeks before study. None of the women were taking oral contraceptives and all had a history of regular menstrual cycles. The experimental protocol was started between 0800-0900 h. The subjects had been fasting (except for water) since the evening meal of the day before. The studies were performed in the recumbent position and the subjects were kept awake. An indwelling needle was inserted into
Group 2 (one man and one woman, 26-36 yr old) Synthetic 1-34 bovine PTH (bPTH) fragment (180 jug; Beckman, Geneva, Switzerland) was administered instead of parathyroid extract in the same conditions as for group 1. This synthetic peptide had a specific activity of approximately 5.6 MRC (Medical Research Council) U/jug. Group 3 (two men and two women, 25-36 yr old)
Synthetic 1-34 human PTH (hPTH) fragment (95 /ig; Armour-Montagu, Paris, France) was administered in the same conditions as the other PTH Received June 8,1977. Address requests for reprints to: Prof. R. Ardaillou, peptides used in groups 1 and 2, respectively. This Service d'Explorations Fonctionnelles and Unite de Re- synthetic peptide was prepared according to the cherches Inserm 64, Hopital Tenon, 75020 Paris, France. sequence proposed by Niall et al. (5). 18
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EFFECT OF PTH ON PLASMA PRL
19
centration corresponded to (Bo/T) — 2 SEM and the midrange concentration to (B/Bo) = 0.5. It was Disodium EDTA (50 mg/kg BW; Laroche-Na- verified that high concentrations of bPTH and of varron, Paris, France) dissolved in 0.9% sodium 1-34 hPTH or bPTH did not inhibit, even slightly, chloride was administered ov«r 2 h at 4 ml/min. the binding of [125I]PRL to its specific antibodies. The control solution without EDTA was infused at The standard used for TSH assay corresponded to the same rate during the hour preceding and the 2 5 MRC U/mg (Medical Research Council; batch h after EDTA administration. Blood samples were 68/38). The lowest detectable TSH concentration taken every 30 min. was 0.2 ng/ml. For cAMP assay, 2 ml blood were collected in Group 5 (one man and one woman, 25-32 yr old) tubes containing dry heparin and 200 jul 0.05 M Each subject ingested 1 g L-dopa (Roche, Paris, theophylline in saline. After extraction (8), cAMP France) 2 h before the iv infusion of 1-34 bPTH in was measured using the kit purchased from the the same conditions as for group 2, except for the Radiochemical Center (Amersham, UK). following modifications: the control period before PTH administration lasted 2 h and supplementary Results blood samples were taken 30 and 1 min before Ldopa ingestion. Groups 1 and 2 Group 4 (two men and two women, 26-35 yr old)
' Assay methods The following determinations were carried out in the plasma obtained from each blood sample: sodium and potassium by emission flame photometry (II Meter apparatus, model 243); calcium by absorption flame photometry (Perkin-Elmer apparatus, model 300); osmolality by cryoscopy (Fiske apparatus, model 130); and phosphorus on a Technicon autoanalyser with the usual technique. Unchelated calcium was also measured by automatic fluorometric titration, using EGTA as the calcium chelator (6), in plasma from the subjects of group 4 who had received disodium EDTA. Hormones were assayed in sensitive and specific RIAs. PTH was measured according to Berson et al. (7) in plasma samples of 100 /il using highly purified bPTH (Inolex Pharmaceuticals, Glenwood, IL) both as tracer and standard and antiserum coded 211:32 (Welcome reagents Ltd, UK). Standard tubes contained 100 jul plasma from patients with hypoparathyroidism. For the samples from the patients of groups 2 and 5 who had received 1-34 bPTH, the standard tubes were prepared with this same peptide which competitively inhibits the binding of 125I-labeled 1-84 bPTH to the antibody used. Plasma PTH was not measured in patients from group 3. PRL and TSH were measured using t the CIS kits purchased from Commissariat a l'Energie Atomique (Gif-sur-Yvette, France). The standard used for PRL assay corresponded to 40 MRC U/mg (Medical Research Council, Mill Hill, UK; batch 71/222). The lowest detectable PRL concentration and the midrange PRL concentrations were 0.3 and 16.7 ng/ml, respectively. These values are the means of the data derived from 15 individual RIA curves. The lowest detectable cony
Baseline plasma PRL levels ranged from 3-11 ng/ml. An immediate increase occurred after bPTH administration. The peak levels were obtained after 30 min and reached two to six times the basal levels. There was then a decrease in plasma PRL in spite of the maintenance of PTH infusion. Plasma PRL returned close to control levels or remained slightly elevated 60 min after the end of PTH administration. Immunoreactive PTH (IR PTH) markedly increased after PTH administration, whatever the peptide used. The time course was similar to that observed with plasma PRL, but the levels reached at the end of the study were still clearly greater than the control values. cAMP also rose markedly during PTH administration. The peak values were observed simultaneously with those of PRL and of IR PTH and reached 3-12 times the baseline levels (Figs. 1 and 2). Two-factor (subjects and treatment) analysis of variance of the pooled data of groups 1 and 2 showed there was a significant rise (P < 0.01) of plasma PRL, PTH, and cAMP when the two control blood collections were compared to the two first blood collections after PTH administration. There was no significant change in TSH plasma levels. Similarly, plasma osmolality, sodium, potassium, calcium, and phosphorus were not modified. Group 3 Baseline plasma PRL ranged from 3-9
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 11 November 2015. at 00:01 For personal use only. No other uses without permission. . All rights reserved.
20
ISAAC ET AL. 1-84 b PTH 450 U.S.P.
40
JCE&M Vol47
1978 Nol
lality, or electrolyte concentrations.
5%Glucose, 27. H.S.A. PRL ng/ml
Group 4 Disodium EDTA infusion produced a decrease both in total calcium assayed by absorption photometry and in uncomplexed calcium estimated using complexometry (in this technique, calcium is estimated from the amount of EGTA necessary to obtain a total chelation). As foreseen, the latter value diminished more markedly. Plasma IR PTH significantly increased from 1.0 ± 0.12 to 1.6 ± 0.23 ng/ml after EDTA administration during 1 h. There was a parallel and significant increase
30
20
(1-34) b PTH - 180 ,,g PRL ng/ml 0 200
5%Glucose, 2 % H.S.A.
AMP pmole /ml
150
100
50
IR PTH ng/ml 30
60 75 90 105 120
150
180 min
FIG. 1. Plasma PRL, IR PTH, and cAMP before, during, and after iv infusion of bovine parathyroid extract in three normal subjects.
ng/ml. There was an immediate increase after PTH administration similar to that obtained for groups 1 and 2. The peak values were 2-4 o times the control ones and were observed beAMP tween 30-45 min after the beginning of PTH 200 pmole/ml infusion. Plasma cAMP also rose, as in groups 1 and 2, and, similarly to plasma PRL, re- 150 turned to control levels or slightly higher after the administration of PTH had been stopped 100 (Fig. 3). Two-factor (subjects and treatment) analysis of variance confirmed that the rise of 50 plasma PRL and plasma cAMP compared to the control values was significant (P < 0.01). 0 30 60 75 90 105 120 150 180 min Plasma IR PTH was not measured in this FIG. 2. Plasma PRL, IR PTH, and cAMP before, during, group. As in groups 1 and 2, there was no and after iv infusion of synthetic 1-34 bPTH fragment in change in TSH plasma levels, plasma osmo- two normal subjects.
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EFFECT OF PTH ON PLASMA PRL
Vol. 47, No. 1 Printed in U.S.A.
Effect of Parathyroid Hormone on Plasma Prolactin in Man ROLAND ISAAC, ROBERT E. MERCERON, GENEVlfiVE CAILLENS, JEAN-PAUL RAYMOND, AND RAYMOND ARDAILLOU Service d'Explorations Fonctionnelles and Unite de Recherches INSERM 64 (R.I., G.C., R.A.), Hbpital Tenon, 75020 Paris, France; and Service d'Endocrinologie (R.E.M., J.-P.R.), Hbpital Beaujon, 92110 Clichy, France ABSTRACT. The iv infusion of parathyroid extract or the synthetic fragments of 1-34 bovine or human parathyroid hormone produced a rapid and marked increase of plasma PRL in normal subjects. The stimulation of the release of endogenous parathyroid hormone by administration of disodium EDTA also resulted in a parallel increase of plasma PRL. Parathyroid hormone did not act via plasma cAMP, as the plasma level reached by this nucleotide was too small to produce PRL release.
The ingestion of L-dopa 2 h before parathyroid hormone infusion suppressed the PRL response, suggesting that dopamine and parathyroid hormone interact at a common site. As it has been recently shown that PRL stimulates the renal synthesis of 1,25-dihydroxycholecalciferol, the present data suggest that the effect of parathyroid hormone on this synthesis may be due to the increase in plasma PRL. (J Clin Endocrinol Metab 47: 18, 1978)
T
a brachial vein and 5% glucose or 0.9% saline, according to the protocol, was administered iv through a catheter positioned in the opposite arm for at least 30 min before the first blood collection. The subjects were divided into five groups, each corresponding to a different study protocol.
HE secretion of several anterior pituitary hormones is influenced by a variety of factors including the intracellular concentration of calcium (1) and cAMP (2, 3). As the increase of these two parameters is the main cellular effect of parathyroid hormone [PTH (4)], we decided to study the role of an increase in plasma PTH on the plasma concentration of some anterior pituitary hormones. Although the anterior hypophysis has never been demonstrated as a site for PTH specific receptors, a clear-cut increase in plasma PRL was observed which is reported in the present study.
Group 1 (two men and one woman, 22-38 yr old) Parathyroid extract (450 USP; Eli Lilly and Co., Indianapolis, IN.) was administered iv over 1 h in 5% glucose containing 2% human serum albumin at 0.75 ml/min. The control solution without PTH was infused at the same rate during the hour preceding and the hour after PTH administration. Blood samples were taken every 30 min during the control periods and every 15 min during the administration of PTH.
Materials and Methods Fifteen normal volunteers (eight men and seven women) ranging in age from 22-38 yr were studied. All were within 5% of their ideal body weight and had not ingested any medications for at least 2 weeks before study. None of the women were taking oral contraceptives and all had a history of regular menstrual cycles. The experimental protocol was started between 0800-0900 h. The subjects had been fasting (except for water) since the evening meal of the day before. The studies were performed in the recumbent position and the subjects were kept awake. An indwelling needle was inserted into
Group 2 (one man and one woman, 26-36 yr old) Synthetic 1-34 bovine PTH (bPTH) fragment (180 jug; Beckman, Geneva, Switzerland) was administered instead of parathyroid extract in the same conditions as for group 1. This synthetic peptide had a specific activity of approximately 5.6 MRC (Medical Research Council) U/jug. Group 3 (two men and two women, 25-36 yr old)
Synthetic 1-34 human PTH (hPTH) fragment (95 /ig; Armour-Montagu, Paris, France) was administered in the same conditions as the other PTH Received June 8,1977. Address requests for reprints to: Prof. R. Ardaillou, peptides used in groups 1 and 2, respectively. This Service d'Explorations Fonctionnelles and Unite de Re- synthetic peptide was prepared according to the cherches Inserm 64, Hopital Tenon, 75020 Paris, France. sequence proposed by Niall et al. (5). 18
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EFFECT OF PTH ON PLASMA PRL
19
centration corresponded to (Bo/T) — 2 SEM and the midrange concentration to (B/Bo) = 0.5. It was Disodium EDTA (50 mg/kg BW; Laroche-Na- verified that high concentrations of bPTH and of varron, Paris, France) dissolved in 0.9% sodium 1-34 hPTH or bPTH did not inhibit, even slightly, chloride was administered ov«r 2 h at 4 ml/min. the binding of [125I]PRL to its specific antibodies. The control solution without EDTA was infused at The standard used for TSH assay corresponded to the same rate during the hour preceding and the 2 5 MRC U/mg (Medical Research Council; batch h after EDTA administration. Blood samples were 68/38). The lowest detectable TSH concentration taken every 30 min. was 0.2 ng/ml. For cAMP assay, 2 ml blood were collected in Group 5 (one man and one woman, 25-32 yr old) tubes containing dry heparin and 200 jul 0.05 M Each subject ingested 1 g L-dopa (Roche, Paris, theophylline in saline. After extraction (8), cAMP France) 2 h before the iv infusion of 1-34 bPTH in was measured using the kit purchased from the the same conditions as for group 2, except for the Radiochemical Center (Amersham, UK). following modifications: the control period before PTH administration lasted 2 h and supplementary Results blood samples were taken 30 and 1 min before Ldopa ingestion. Groups 1 and 2 Group 4 (two men and two women, 26-35 yr old)
' Assay methods The following determinations were carried out in the plasma obtained from each blood sample: sodium and potassium by emission flame photometry (II Meter apparatus, model 243); calcium by absorption flame photometry (Perkin-Elmer apparatus, model 300); osmolality by cryoscopy (Fiske apparatus, model 130); and phosphorus on a Technicon autoanalyser with the usual technique. Unchelated calcium was also measured by automatic fluorometric titration, using EGTA as the calcium chelator (6), in plasma from the subjects of group 4 who had received disodium EDTA. Hormones were assayed in sensitive and specific RIAs. PTH was measured according to Berson et al. (7) in plasma samples of 100 /il using highly purified bPTH (Inolex Pharmaceuticals, Glenwood, IL) both as tracer and standard and antiserum coded 211:32 (Welcome reagents Ltd, UK). Standard tubes contained 100 jul plasma from patients with hypoparathyroidism. For the samples from the patients of groups 2 and 5 who had received 1-34 bPTH, the standard tubes were prepared with this same peptide which competitively inhibits the binding of 125I-labeled 1-84 bPTH to the antibody used. Plasma PTH was not measured in patients from group 3. PRL and TSH were measured using t the CIS kits purchased from Commissariat a l'Energie Atomique (Gif-sur-Yvette, France). The standard used for PRL assay corresponded to 40 MRC U/mg (Medical Research Council, Mill Hill, UK; batch 71/222). The lowest detectable PRL concentration and the midrange PRL concentrations were 0.3 and 16.7 ng/ml, respectively. These values are the means of the data derived from 15 individual RIA curves. The lowest detectable cony
Baseline plasma PRL levels ranged from 3-11 ng/ml. An immediate increase occurred after bPTH administration. The peak levels were obtained after 30 min and reached two to six times the basal levels. There was then a decrease in plasma PRL in spite of the maintenance of PTH infusion. Plasma PRL returned close to control levels or remained slightly elevated 60 min after the end of PTH administration. Immunoreactive PTH (IR PTH) markedly increased after PTH administration, whatever the peptide used. The time course was similar to that observed with plasma PRL, but the levels reached at the end of the study were still clearly greater than the control values. cAMP also rose markedly during PTH administration. The peak values were observed simultaneously with those of PRL and of IR PTH and reached 3-12 times the baseline levels (Figs. 1 and 2). Two-factor (subjects and treatment) analysis of variance of the pooled data of groups 1 and 2 showed there was a significant rise (P < 0.01) of plasma PRL, PTH, and cAMP when the two control blood collections were compared to the two first blood collections after PTH administration. There was no significant change in TSH plasma levels. Similarly, plasma osmolality, sodium, potassium, calcium, and phosphorus were not modified. Group 3 Baseline plasma PRL ranged from 3-9
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 11 November 2015. at 00:01 For personal use only. No other uses without permission. . All rights reserved.
20
ISAAC ET AL. 1-84 b PTH 450 U.S.P.
40
JCE&M Vol47
1978 Nol
lality, or electrolyte concentrations.
5%Glucose, 27. H.S.A. PRL ng/ml
Group 4 Disodium EDTA infusion produced a decrease both in total calcium assayed by absorption photometry and in uncomplexed calcium estimated using complexometry (in this technique, calcium is estimated from the amount of EGTA necessary to obtain a total chelation). As foreseen, the latter value diminished more markedly. Plasma IR PTH significantly increased from 1.0 ± 0.12 to 1.6 ± 0.23 ng/ml after EDTA administration during 1 h. There was a parallel and significant increase
30
20
(1-34) b PTH - 180 ,,g PRL ng/ml 0 200
5%Glucose, 2 % H.S.A.
AMP pmole /ml
150
100
50
IR PTH ng/ml 30
60 75 90 105 120
150
180 min
FIG. 1. Plasma PRL, IR PTH, and cAMP before, during, and after iv infusion of bovine parathyroid extract in three normal subjects.
ng/ml. There was an immediate increase after PTH administration similar to that obtained for groups 1 and 2. The peak values were 2-4 o times the control ones and were observed beAMP tween 30-45 min after the beginning of PTH 200 pmole/ml infusion. Plasma cAMP also rose, as in groups 1 and 2, and, similarly to plasma PRL, re- 150 turned to control levels or slightly higher after the administration of PTH had been stopped 100 (Fig. 3). Two-factor (subjects and treatment) analysis of variance confirmed that the rise of 50 plasma PRL and plasma cAMP compared to the control values was significant (P < 0.01). 0 30 60 75 90 105 120 150 180 min Plasma IR PTH was not measured in this FIG. 2. Plasma PRL, IR PTH, and cAMP before, during, group. As in groups 1 and 2, there was no and after iv infusion of synthetic 1-34 bPTH fragment in change in TSH plasma levels, plasma osmo- two normal subjects.
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EFFECT OF PTH ON PLASMA PRL
