Altered Dopaminergic Regulation of Thyrotrophin Release in Patients With Prolactinomas: Comparison With Other Tests of Hypothalamic‐pituitary Function

Scanlon, M. F.; Rodríguez-Arnao, M. D.; McGregor, A.M.; Weightman, D.; Lewis, Malcolm J.; Cook, David B.; Gómez-Pan, A.; Hall, R. J. C.

doi:10.1111/j.1365-2265.1981.tb00608.x

Cited by 108 publications

(53 citation statements)

References 45 publications

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“…Prolactin seems to adjust the activity and receptor density of dopamine, having a modulatory effect on central dopamine transmission.Thus, the prolactinoma patients seem to experience an altered dopaminergic background, with the data remaining rather controversial. It has been hypothesized that tumoral hyperprolactinemia is an autonomous condition of increased central dopaminergic tone due to elevated prolactin release [13,16,24,25]. On the other hand, sustained hyperprolactinemia is hypothesized as downregulating normal effects by reducing the central dopaminergic tone [26] with the dopaminergic neurons becoming refractory to the elevated prolactin levels [15].…”

Section: Discussionmentioning

confidence: 99%

Distinct Dopaminergic Personality Patterns in Patients with Prolactinomas: A Comparison with Nonfunctioning Pituitary Adenoma Patients and Age- and Gender-Matched Controls

Athanasoulia¹,

Ising

Mantzoros

et al. 2012

Neuroendocrinology

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Introduction: Personality patterns such as extraversion and novelty seeking have been associated with an altered dopaminergic activity in healthy subjects. Patients with prolactinomas have been described as exhibiting an altered dopaminergic tone and are often treated with dopamine agonists. Little is known about the personality traits of this patient group. Hence, we aimed at examining whether patients with prolactinomas exhibit modified personality patterns compared to patients with nonfunctioning pituitary adenomas and healthy controls. Subjects/Methods: In this cross-sectional study, 86 patients with prolactinomas and 58 patients with nonfunctioning pituitary adenomas (NFPA) were compared with 172 mentally healthy age- and gender-matched controls. To assess personality traits, standardized personality questionnaires (Eysenck personality questionnaire-EPQ-RK and Tridimensional Personality Questionnaire devised by Cloninger-TPQ) were administered. Results: Patients with either prolactinomas or NFPA showed a distinct personality profile compared to the normal population, characterized by increased neuroticism and they also answered in a socially desirable mode. On harm-avoidant total and subscales, they presented with a higher fear of uncertainty and also increased fatigability and asthenia. The prolactinoma patients, when contrasted with the ‘clinical’ control group of patients with NFPA and after post hoc tests for multiple comparisons following the Bonferroni-Holm procedure showed significantly reduced extraversion (p = 0.044) and increased shyness with strangers (p = 0.044), tending to be more neurotic and present lower scores in the novelty seeking subscale impulsiveness. Conclusion: This is, to our knowledge, the first study providing new evidence of an altered personality profile of prolactinoma patients which might affect the patient-doctor relationship, treatment and patient’s quality of life.

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Section: Discussionmentioning

confidence: 99%

Distinct Dopaminergic Personality Patterns in Patients with Prolactinomas: A Comparison with Nonfunctioning Pituitary Adenoma Patients and Age- and Gender-Matched Controls

Athanasoulia¹,

Ising

Mantzoros

et al. 2012

Neuroendocrinology

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“…However, there might be one possibility that in a hypothyroid state PRL synthesis in the lactotrophs is apt to be activated by increasing thyroid hormone levels, and this activation overcomes the inhibitory effects of hypothalamic dopamine and thyroid hormones on PRL release. The magnitude of PRL response to sulpiride (a dopamine receptor blocker) indirectly reflects the degree of hypothalamic dopaminergic inhibition, since sulpiride can enhance the PRL release as a result of blocking the endogenous dopaminergic inhibition (Scanlon et al 1981;Hanew et al 1983). Accordingly, the increased PRL response to sulpiride during the thyroid replacement suggests that hypothalamic dopaminergic inhibition on the lactotrophs is slightly enhanced in the patients with primary hypothyroidism.…”

Section: Resultsmentioning

confidence: 99%

Enhanced prolactin secretion in patients with primary hypothyroidism during thyroid replacement.

Sato

Hanew

Sasaki

et al. 1984

Tohoku J. Exp. Med.

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Thyroid hormones are known to exert some influence on prolactin (PRL) secretion indirectly via the hypothalamic dopaminergic system and directly at the level of pituitary gland. In order to study the effect of thyroid hormones on the activity of hypothalamic dopamine neurons, lactotrophs and thyrotrophs, we administered increasing doses of thyroid hormones to patients with primary hypothyroidism, and examined the changes of basal PRL, TSH and PRL responses to a dopamine receptor blocker (sulpiride).Among 24 patients with primary hypothyroidism, hyperprolactinemia was observed in 10 cases (18.0-236 ng/ml, mean +S.E. 58.6+20.0 ng/ml), while elevated TSH levels were observed in all of them (6.6-972,uU/ml, mean ±S.E. 231.4+53.9,aU/ml). There was a significant negative relationship between plasma T3 or T4 levels and basal plasma TSH levels (p <0.05), whereas a poor correlation was observed between the thyroid hormones and basal plasma PRL levels (r = -0.25, p >0.05). Following the administration of gradually increasing doses of thyroid hormones, plasma PRL showed paradoxical and transient increases, while plasma TSH decreased steadily.Plasma PRL response to sulpiride also became exaggerated during the treatment.The elevated basal PRL level and the enhanced response to sulpiride turned to be within the normal range when the patients became euthyroid by treatment.These results may indicate that thyroid hormones stimulate not only hypothalamic dopaminergic activity, but also the lactotroph activity in a long term hypothyroid state. Regarding the paradoxical elevation of basal PRL, one can postulate that the activation of lactotroph by a small dose of thyroid hormone may be able to overcome the hypothalamic dopaminergic inhibition. primary hypothyroidism ; thyroid hormone ; prolactin ; sulpiride ; dopaminergic regulation

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“…It is plausible that endogenous dopamine exerted an inhibitory effect on Gil secretion in the above 3 cases, since sulpiride can increase plasma Gil as a result of blockade of endogenous dopaminergic inhibition (MacLeod and Robyn 1977; Scanlon et al 1981). In case 2 plasma Gil responses to TRH and sulpiride were observed even after the plasma Gil was normalized by surgery.…”

Section: Discussionmentioning

confidence: 99%

Plasma growth hormone responses to sulpiride in patients with acromegaly.

Hanew

Sato

Sasaki

et al. 1984

Tohoku J. Exp. Med.

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The role of endogenous dopamine (DA) on plasma GH secretion was studied in 12 patients with active acromegaly.After intramuscular administration of 100 mg sulpiride, 3 out of 12 patients showed distinct increases in their plasma GH (cases 1-3:sulpirideresponders).The GH increases far exceeded the ranges of physiological fluctuation in two cases studied (case 1 & 3). After domperidone administration, case 3 showed a quite similar GH increase as after sulpiride.Plasma GH responses to TRH and sulpiride were still observed in case 2 even after the basal GH levels were normalized by the transsphenoidal hypophysectomy.The three sulpiride-responders showed so-called paradoxical GH decreases following the administration of L-dopa (500 mg, p.o.) or DA (5pg/kg/min over 90 min, i.v.). However, the basal plasma PRL levels and the responses to sulpiride in these 3 cases were not homogeneous.These results indicate that endogenous DA has a tonic inhibitory effect on GH secretion in some cases of acromegaly, and that tumorous somatotrophs rather than elevated GH levels are the critical factor for such inhibition. Further, the sensitivities of somatotrophs and lactotrophs to DA appeared to be heterogeneous in acromegalic patients.acromegaly ; GH ; sulpiride ; domperidone ; dopamine ; TRH It is well known that acromegalic patients are apt to show paradoxical growth hormone (GH) decreases to exogenously administered dopamine (DA) and dopaminergic agonists Liuzzi et al. 1974; Oppizi et al. 1980). Similar GH decreases to these agents are also observed in GH-secreting adenomas in vitro (Mashiter et al. 1977;Peillon et al. 1979). These findings suggest a role of DA in the secretion of GH in acromegalic patients. Effects produced by pharmacological doses of DA-agonists, however, do not necessarily imply that endogenous DA has a direct suppressive effect on the somatotrophs.To test whether this is in fact the case, we examined the effect of DA-

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Altered Dopaminergic Regulation of Thyrotrophin Release in Patients With Prolactinomas: Comparison With Other Tests of Hypothalamic‐pituitary Function

Cited by 108 publications

References 45 publications

Distinct Dopaminergic Personality Patterns in Patients with Prolactinomas: A Comparison with Nonfunctioning Pituitary Adenoma Patients and Age- and Gender-Matched Controls

Distinct Dopaminergic Personality Patterns in Patients with Prolactinomas: A Comparison with Nonfunctioning Pituitary Adenoma Patients and Age- and Gender-Matched Controls

Enhanced prolactin secretion in patients with primary hypothyroidism during thyroid replacement.

Plasma growth hormone responses to sulpiride in patients with acromegaly.

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