The role of prolactin in the inhibitory action of bromocriptine on growth hormone secretion in acromegaly
33
Citation
0
Reference
10
Related Paper
Citation Trend
Abstract:
Abstract. Bromocriptine treatment results in clinical improvement and inhibition of plasma GH levels in only part of the acromegalic patients. The possible role of the simultaneous presence of Prl and GH in GH-secreting pituitary adenomas was investigated with regard to the inhibitory action of bromocriptine on GH secretion and the paradoxical increase of GH release in reaction to TRH. Surgically obtained pituitary tumour tissue from 35 consecutive acromegalic patients was studied immunohistochemically. In 21 patients no Prl was present in the tumour tissue. These patients had normal plasma Prl levels. In the other 14 patients Prl was present in the tumour tissue. Hyperprolactinaemia was found in 10 of these 14 patients. Plasma GH levels from 2 till 10 h after the administration of 2.5 mg bromocriptine measured before operation were significantly more suppressed in the patients with mixed GH/Prl-containing than in those with pure GH-containing pituitary adenomas, being 38 ± 4% and 65 ± 4% of basal values, respectively ( P < 0.01). The response of GH to TRH, however, did not differ significantly between the two groups. Conclusions: 1. In about 70% of patients with 'mixed' GH/Prl containing adenomas, hyperprolactinaemia is present. 2. The simultaneous presence of Prl and GH in a GH-secreting pituitary tumour increases the sensitivity of GH secretion to bromocriptine. 3. The plasma Prl level is of value to predict which patients with acromegaly are likely to respond to bromocriptine with an inhibition of GH secretion.Keywords:
Prolactin cell
저자는 유즙분비 억제를 목적으로 Bromocriptine을 투여한 15예와 Estrogen을 투여한 10예에서 임상적 효과와 혈청 prolactin치의 변화를 수유군과 비교 관찰하여 다음과 같은 결론을 얻었다. 1. 분만직후 2시간 이내의 혈청 prolactin치는 분만전의 혈청 prolactin치보다 상승하였다.(p<0.01). 2. 수유군에서 혈청 prolactin치는 분만후 제 3 주경에 비임신시의 혈청 prolactin 치로 감소되었다. 3. Estrogen 투여시 유즙분비 억제효과는 부분적이었고 약 40%에서 rebound lactation이 나타났다. 4. Bromocriptine 투여시 유즙분비 억제효과는 우수하였고 7∼13%에서 유즙분비와 유방팽창이 나타 났으나 그 정도는 매우 경미하였다. 5. Bromocriptine 투여시 혈청 prolactin치의 감소는 수유군보다 현저한 차이를 나타내었다. (P<0.01). 6. Bromocriptine과 Estrogen 투여시 약물에 의한 부작용은 관찰할 수 없었다.
Prolactin cell
Cite
Citations (0)
Eleven patients with active acromegaly were treated with bromocriptine for one year or more. Nine showed significant reduction in plasma growth hormone levels and eight improvement with respect to clinical symptoms. No serious side effects were observed.
Cite
Citations (9)
Clinical and hormonal responses to bromocriptine therapy were assessed in 10 patients with acromegaly. Although substantial falls (≧ 50%) in serum GH occurred in only 4 of the patients, subjective clinical improvement and improved glucose tolerance were seen in 9, including 2 subjects in whom serum GH rose in response to bromocriptine. Serum somatomedin levels, measured by both radioimmunoassay and radioreceptor assay, fell in only 2 subjects (both of whom had falls in GH) and did not correlate with clinical status. These results suggest that some of the reported beneficial effects of bromocriptine in acromegaly may be independent of GH secretion or somatomedin generation.
Cite
Citations (14)
Pegvisomant
Cite
Citations (9)
Prolactin cell
Mammary tumor
Cite
Citations (9)
Prolactin cell
Pituitary Tumors
Cite
Citations (1)
Bromocriptine treatment of lactating rats, or removal of the litter, led to a decrease in the number of insulin receptors in the mammary gland and an increase in the concentration of insulin in the serum. Bromocriptine also induced a decrease in the concentration of both prolactin and progesterone in the serum, whilst concurrent treatment with the former but not the latter prevented all the effects of bromocriptine for 48 h. Removal of the litter produced a similar decrease in the concentration in the serum of prolactin but not of progesterone. Treatment with prolactin prevented all of the effects of removal of the litter for 24 but not 48 h. This suggests that these effects of prolactin may require a mammary gland actually synthesizing milk since the gland rapidly fills with milk after removing the litter whereas milk removal continues to take place in bromocriptine-treated rats allowed to continue nursing their litters.
Litter
Prolactin cell
Prolactin receptor
Cite
Citations (51)
The effect of bromocriptine withdrawal after long-term treatment on prolactin levels has been investigated in thirty-seven patients with prolactinomas. In ten patients with macroprolactinomas and post-operatively excessively high prolactin levels persisting suppression of prolactin secretion after bromocriptine withdrawal has been observed. This effect was not observed in patients with microprolactinomas or macroprolactinomas with only moderately elevated prolactin levels. The degree of persisting suppression correlated to the height of prolactin levels before treatment and to the duration of bromocriptine therapy. No correlation was found between the rise of prolactin levels after bromocriptine withdrawal and withdrawal time. It is suggested that the persisting suppression of prolactin levels is a sequence of reduction in tumour size. This anti-proliferative action of bromocriptine seems to be specific for the prolactin secreting cells in macroprolactinomas with high proliferation rate and high prolactin turn-over. These findings offer new possibilities in the management of patients with macroprolactinomas.
Prolactinoma
Prolactin cell
Cite
Citations (62)
Cite
Citations (27)