Prolactin receptor signaling during platelet activation

Mitophagy involved the biological processes of hormones

Mitochondria fulfill vital functions in energy production, maintaining ion balance, and facilitating material metabolism. Mitochondria are sacrificed to protect cells or induce apoptosis when the body is under stress. The regulatory pathways of mitophagy include both ubiquitin-dependent and non-dependent pathways. The involvement of mitophagy has been demonstrated in the onset and progression of numerous diseases, highlighting its significant role. Endocrine hormones are chemical substances secreted by endocrine organs or endocrine cells, which participate in the regulation of physiological functions and internal environmental homeostasis of the body. Imbalances in endocrine hormones contribute to the development of various diseases. However, the precise impact of mitophagy on the physiological and pathological processes involving endocrine hormones remains unclear. This article aims to comprehensively overview recent advancements in understanding the mechanisms through which mitophagy regulates endocrine hormones.

The effects of pituitary and thyroid disorders on haemostasis: potential clinical implications

Disturbances of coagulation and fibrinolysis are usually multifactorial and growing evidence suggests that endocrinopathies modulate the haemostatic balance. The thrombotic alterations in endocrine disorders range from mild laboratory clotting abnormalities with little clinical significance to serious thrombotic and bleeding disorders directly related to hormonal disturbances. This literature review focuses on presenting the current data on the effects of thyroid and pituitary disorders on various parameters of the haemostatic system. With the exception of overt hypothyroidism which appears to cause a bleeding tendency, the rest of the endocrinopathies discussed in this review (subclinical hypothyroidism, hyperthyroidism, endogenous hypercortisolaemia, growth hormone deficiency, acromegaly, prolactinoma/hyperprolactinaemia and hypogonadotrophic hypogonadism) are associated with a hypercoagulable and hypofibrinolytic state, increasing the overall cardiovascular risk and thromboembolic potential in these patients. In most studies, the haemostatic abnormalities seen in endocrine disorders are usually reversible with successful treatment of the underlying condition and biochemical disease remission. High-quality studies on larger patient cohorts are needed to produce robust evidence on the effects of endocrine disorders and their therapeutic interventions on coagulation and fibrinolysis, as well as on the long-term mortality and morbidity outcomes in association with endocrine-related haemostatic imbalance. Given the rarity of some of the endocrine disorders, multicentre studies are required to achieve this target.

Mean platelet volume in patients with prolactinoma

OBJECTIVE

Prolactin is a multifunctional pituitary hormone. The effect of prolactin on platelet activation is not well understood. Prolactinomas are the most common type of pituitary adenomas, and they are medically responsive to dopamine agonists. Mean platelet volume (MPV) is a marker of platelet function and activation. The aim of this study was to evaluate MPV values before and 6 months of cabergoline treatment when normoprolactinemia was achieved.

SUBJECTS AND METHODS

A total of 101 newly diagnosed prolactinoma patients and 102 healthy control subjects were included in the study. Patients with hematological disorders that affect MPV and those on medications were excluded. Prolactin, platelet count and MPV levels were recorded before and 6 months after the initiation of cabergoline treatment (0.5 to 1 mg, two times a week).

RESULTS

There was no significant difference in platelet count and MPV before and after 6 months of treatment with cabergoline in patients with prolactinoma compared with the control group (p > 0.05).

CONCLUSION

Our results showed that MPV, a marker of platelet function, was unchanged in patients with prolactinoma.

The effect of prolactin levels on MPV in women with PCOS

OBJECTIVE

Polycystic ovary syndrome (PCOS) is associated with cardiovascular risk factors including hypertension, obesity, hyperlipidaemia and glucose intolerance. Several studies demonstrated the link between PCOS and an increased risk of cardiovascular disease. Platelets play a crucial role in the development of atherothrombotic disease. Mean platelet volume (MPV) is a marker of platelet size that reflects its activity. Research points to a link between prolactin (PRL) and platelet activation. The purpose of this study was to investigate whether prolactin levels are associated with MPV in women with PCOS.

DESIGN

The research was designed as a cross-sectional study.

PATIENTS

Participants were divided into three groups-PCOS patients with mildly elevated PRL levels (n = 72), patients with PCOS with normal PRL levels (n = 207) and healthy controls (n = 90). They were body mass index and age-matched and consecutively recruited.

MEASUREMENTS

Complete blood counts, serum glucose, prolactin, insulin, lipids, high-sensitivity C-reactive protein and free-testosterone levels were measured.

RESULTS

Among the three groups, MPV levels were higher in women with PCOS having mildly elevated PRL levels (P < 0·001) and MPV was found to be correlated with PRL levels (r = 0·387, P < 0·001). Multiple regression analysis showed that PRL levels were associated with MPV levels (R(2) = 0·239, β = 0·354, P < 0·001).

CONCLUSION

Mean platelet volume levels are significantly increased in women with PCOS having mildly elevated PRL. Our results suggest that there is a link between prolactin and MPV levels. In women with PCOS, elevated PRL levels may increase the risk of developing atherothrombotic events via the activation of platelets.

Serum prolactin and macroprolactin in heart failure: no relation to established laboratory or clinical parameters

Background

A few smaller studies have reported that the prolactin concentration is elevated in connection with heart failure. As heart failure is combined with disturbances of several biological systems any or all of which may also influence prolactin concentrations, we wanted to evaluate the relation of prolactin to prognosis in elderly patients.

Methods

A total of 462 elderly patients from a primary health-care centre, all with symptoms of heart failure, were included. In addition to clinical examination including echocardiography, concentrations of prolactin, macroprolactin, C-reactive protein, thyroid-stimulating hormone and N-terminal pro B-type natriuretric peptide (NT-proBNP) were measured. Patients were then followed for 10 y, and all incidents of cardiovascular mortality were registered.

Results

After excluding patients with macroprolactin, hyperprolactinaemia was found in 3.7% of the patients. There were no differences in prolactin concentrations or in the frequency of macroprolactin between patients with heart failure and those with normal cardiac function, defined as left ventricular ejection fraction of at least 50%. No significant correlation could be found between NT-proBNP and prolactin. Neither could any association be found between cardiovascular mortality and prolactin concentration during 10 y of follow-up.

Conclusions

Prolactin concentrations were not associated with cardiovascular mortality or any clinical or biochemical marker of heart failure. Macroprolactin was found in similar frequency among patients with and without heart failure, and showed no correlation with mortality risk.

Prolactin’s role in the pathogenesis of the antiphospholipid syndrome

Increased levels of serum prolactin have been reported in patients with various autoimmune diseases and have been associated with lupus disease activity. Currently, there is a lack of data regarding hyperprolactinaemia in patients with the antiphospholipid syndrome. Hence, this study was carried out in order to evaluate the prevalence and clinical significance of hyperprolactinaemia in antiphospholipid syndrome. A total of 172 European patients with antiphospholipid syndrome and 100 geographically and sex-matched healthy controls were included in the study; none had obvious causes of hyperprolactinaemia. All patients underwent clinical assessment for disease manifestations, in addition to laboratory assessment for serum prolactin, antiphospholipid antibodies and some other biomarkers of autoimmune diseases. The tests were performed utilizing the LIAISON® Analyzer (DiaSorin, Sallugia Italy). Hyperprolactinaemia was detected in 21/172 patients with antiphospholipid syndrome and 0/100 controls (p < 0.001). This significant difference was present in both genders and was obvious even after subgrouping the patients into primary and secondary antiphospholipid syndrome. When clinical features were compared, hyperprolactinaemia was associated with reproductive failure, including early and late pregnancy loss (p < 0.05), as well as intrauterine growth retardation (p < 0.05). Hyperprolactinaemia was negatively related to arthralgias, venous thrombosis, pulmonary microthrombosis, pulmonary hypertension in both primary antiphospholipid syndrome and antiphospholipid syndrome secondary to other diseases, and to neurological manifestations in primary antiphospholipid syndrome (p<0.05). The data indirectly imply that prolactin may play a role in the pathogenesis of antiphospholipid syndrome, especially antiphospholipid syndrome-related reproductive failure.

The coagulation system in endocrine disorders: a narrative review

Endocrine disorders can influence the haemostatic balance. Abnormal coagulation test results have been observed in patients with abnormal hormone levels. Also unprovoked bleeding or thrombotic events have been associated with endocrine disease. The aim of the present review is to summarise the available evidence on the influence of common endocrine disorders on the coagulation system, and their possible clinical implications. We focus on thyroid dysfunction, hyper- and hypocortisolism and growth hormone disturbances, while other endocrine disorders are only briefly discussed. In the published literature a clear bleeding diathesis has only been associated with overt hypothyroidism, mainly mediated by an acquired von Willebrand syndrome. A clinically relevant hypercoagulable state may be present in patients with hyperthyroidism, hypercortisolism or abnormal growth hormone levels, but adequate prospective clinical studies are lacking. Also effects of pheochromocytoma, hyperprolactinaemia and hyperaldosteronism on the coagulation system have been described. It is apparent that unprovoked bleeding and thrombotic episodes can be secondary to endocrine disorders.

Detection of molecular variants of prolactin in human serum, evaluation of a method based on ultrafiltration

BACKGROUND

In human blood, there are several molecular variants of prolactin with different biological effects. There is a need for new methods to detect and quantify these variants in order to fully understand the pathophysiological role of prolactin.

METHODS

A method based on ultrafiltration was optimized, validated and compared to PEG precipitation. Serum samples from 84 patients were analyzed before and after pre treatment on two immunoassays, Elecsys (Roche) and Access (Beckman). Protein G precipitation was used to confirm presence of macroprolactin.

RESULTS

The recovery of prolactin after ultrafiltration was lower than after PEG precipitation. A limit of 40% recovery after PEG precipitation corresponded to 27% recovery after ultrafiltration. Using these limits there were total agreement regarding detection of macroprolactin (r(s)=0.96). In contrast, recovery of prolactin in samples without macroprolactin showed a considerable disagreement between ultrafiltration and PEG precipitation (r(s)=0.48). Within-run CV was 4% for the ultrafiltration method. The correlation coefficient (r) between the immunoassays was 0.96 after ultrafiltration.

CONCLUSIONS

Ultrafiltration can be used to compare different prolactin immunoassays and to detect macroprolactin in assays with interference from PEG. For samples without macroprolactin ultrafiltration may give additional information reflecting individual variations of other molecular variants of prolactin.