Prognostic factors for surgical treatment of prolactin-secreting pituitary adenomas

Introduction

Usually, prolactinomas are treated with dopamine agonists (DA). Surgery is considered an option when the patient cannot bear or does not respond positively to DA therapy.

Aim

This study aims to determine the early and late outcomes of surgery, with particular emphasis on developing prognostic factors for surgical treatment and analyzing risk factors affecting the recurrence of hyperprolactinemia and prolactinoma.

Material and methods

This retrospective study was conducted at the Feofaniya Clinical Hospital of the State Administration of Affairs (Kyiv, Ukraine), evaluating 109 patients' records from 2009 to 2019. The main patients' inclusion criteria were: serum prolactin (PRL) level of more than 100 ng/ml, presence of pituitary adenoma (PA) on MRI, histologically approved PA by microscopy. According to the size of the prolactin-secreting PA (PSPAs) the selected 109 patients were divided into two groups: micro- (≤10 mm, n = 75) and macroadenoma group (10-40 mm, n = 34).

Results

1 month after the operation, PRL levels decreased by 87% (p < 0.001), 12 months-by 93% (p < 0.001). After receiving surgery and DA therapy for 12 months 77.1% of patients achieved biochemical remission. Out of the total number of patients observed, 15.6% (n = 17) had a Knosp score greater than 3. Additionally, in the macroadenoma group, the percentage of patients with a Knosp score greater than 3 was 41,2%, which was significantly higher as compared to the microadenoma group (4%, p < 0.001). In patients with microadenomas a weak reverse correlation between patients' age (r = -0.258, p < 0.026) and positive with tumor size (r = 0.251, p < 0.030) was revealed. In the macroadenoma group significant association was found only between preoperative serum PRL level and tumor size (r = 0.412, p < 0.016). The preoperative PRL can be used as a diagnostic marker for lack of early biochemical remission in patients with PSPAs with diagnostic accuracy 66.9%.

Conclusions

This study found that primary transsphenoidal surgery is an effective treatment in reaching PRL level control in patients with both micro- and macroprolactinomas. The correct and thorough selection of candidates for surgery is crucial to achieve postoperative serum PRL normalization in the vast majority of patients.

Revealing Sexual Dimorphism in Prolactin Regulation From Early Postnatal Development to Adulthood in Murine Models

Serum prolactin (PRL) levels exhibit a gradual rise both in male and female rats from birth to adulthood, with females consistently displaying higher levels compared to age-matched males. This pattern has traditionally been attributed to the development and maturation of endocrine and neuroendocrine networks responsible for regulating PRL synthesis and secretion. However, the effect of dopamine (DA), which acts as an inhibitory factor on lactotroph function, also increases from birth to puberty, particularly in females. Nonetheless, the secretion of PRL remains higher in females compared to males. On the other hand, the observed sex differences in serum PRL levels during early postnatal development cannot be attributed to the influence of estradiol (E2). While serum E2 levels gradually increase after birth, only after 45 days of life do the disparities in E2 levels between females and males become evident. These observations collectively suggest that neither the maturation of hypothalamic DA regulation nor the rise in E2 levels can account for the progressive and sustained elevation in serum PRL levels and the observed sexual dimorphism during postnatal development. This review highlights the importance of recent discoveries in animal models that shed light on inhibitory mechanisms in the control of PRL secretion within the pituitary gland itself, that is intrapituitary mechanisms, with a specific emphasis on the role of transforming growth factor β1 and activins in PRL secretion.

Is prolactin receptor signaling a target in dopamine-resistant prolactinomas?

The hypothalamic neuroendocrine catecholamine dopamine regulates the lactotroph function, including prolactin (PRL) secretion, proliferation, and apoptosis. The treatment of PRL-secreting tumors, formerly known as prolactinomas, has relied mainly on this physiological characteristic, making dopamine agonists the first therapeutic alternative. Nevertheless, the group of patients that do not respond to this treatment has few therapeutical options. Prolactin is another physiological regulator of lactotroph function, acting as an autocrine/paracrine factor that controls PRL secretion and cellular turnover, inducing apoptosis and decreasing proliferation. Furthermore, the signaling pathways related to these effects, mainly JAK/STAT and PI3K/Akt, and MAPK, have been extensively studied in prolactinomas and other tumors as therapeutic targets. In the present work, the relationship between PRL pathophysiology and prolactinoma development is explored, aiming to comprehend the value of PRL and PRLR-associated pathways as exploratory fields alternative to dopamine-related approaches, which are worth physiological characteristics that might be impaired and can be potentially restored or upregulated to provide more options to the patients.

The efficacy and safety of quinagolide in hyperprolactinemia treatment: A systematic review and meta-analysis

PURPOSE

Three dopamine agonists [bromocriptine, cabergoline, and quinagolide (CV)] have been used for hyperprolactinemia treatment for decades. Several studies have reviewed the efficacy and safety of bromocriptine and cabergoline. However, no systematic review or meta-analysis has discussed the efficacy and safety of CV in hyperprolactinemia and prolactinoma treatment.

METHODS

Five medical databases (PubMed, Web of Science, Embase, Scopus, and Cochrane Library) were searched up to 9 May 2022 to identify studies related to CV and hyperprolactinemia. A meta-analysis was implemented by using a forest plot, funnel plot, sensitivity analysis, meta-regression, and Egger's test via software R 4.0 and STATA 12.

RESULTS

A total of 1,211 studies were retrieved from the five medical databases, and 33 studies consisting of 827 patients were finally included in the analysis. The pooled proportions of patients with prolactin concentration normalization and tumor reduction (>50%) under CV treatment were 69% and 20%, respectively, with 95% confidence intervals of 61%-76% and 15%-28%, respectively. The pooled proportion of adverse effects was 13%, with a 95% confidence interval of 11%-16%.

CONCLUSION

Our study showed that CV is not less effective than cabergoline and bromocriptine in treating hyperprolactinemia, and the side effects were not significant. Hence, this drug could be considered an alternative first-line or rescue treatment in treating hyperprolactinemia in the future.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42022347750.

Neuropsychological Alterations of Prolactinomas' Cognitive Flexibility in Task Switching

Prolactinomas have been reported to impair cognition in broad aspects. However, few studies investigated the influence of prolactinomas on cognitive flexibility never mentioning the underlying neural and electrophysiological mechanism. We recorded scalp electroencephalography (EEG) in a colour-shape switching task. Patients with prolactinomas showed longer reaction time in switch trials and larger switch costs relative to healthy controls (HCs). Compared to HCs who showed stronger frontal theta activity in switch trials, the generally weak frontal theta activity in patients implied that they could not afford the executive control to configure task sets. Meanwhile, machine-learning based classification revealed that patients manifested non-selective brain patterns in response to different task types (colour vs. shape task) and different task states (switch vs. repeat state), which collectively suggested the cognitive dysfunction in preparation for a changing environment. Compared to HCs who showed stronger frontoparietal synchronization in switch trials, this enhanced frontoparietal connectivity was disrupted among patients with severe prolactinomas. This finding implicated greater hyperprolactinemia was linked to a larger decrease in cognitive performance. Taken together, the present study highlighted frontal theta power, and frontoparietal connectivity at theta band as the electrophysiological markers of the impaired cognitive flexibility and task control in patients with prolactinomas.

Transsphenoidal surgery for prolactinomas in male patients: a retrospective study

Male patients with prolactinomas usually present with typical hyperprolactinemia symptoms, including sexual dysfunction and infertility. However, clinical factors related to sexual dysfunction and surgical outcomes in these patients remain unclear. This study aimed to investigate the outcomes of male patients with prolactinomas after transsphenoidal surgery and the risk factors affecting sexual dysfunction. This study was conducted on 58 male patients who underwent transsphenoidal surgery for prolactinomas between May 2014 and December 2020 at the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. We evaluated the sexual function of patients before and after surgery through International Index of Erectile Function-5 scores, libido, and frequency of morning erection. Of the 58 patients, 48 (82.8%) patients had sexual intercourse preoperatively. Among those 48 patients, 41 (85.4%) patients presented with erectile dysfunction. The preoperative International Index of Erectile Function-5 scores in patients with macroprolactinomas were significantly higher than those in patients with giant prolactinomas (17.63 ± 0.91 vs 13.28 ± 1.43; P = 0.01). Postoperatively, the incidence of erectile dysfunction was 47.9%, which was significantly lower than that preoperatively (85.4%; P = 0.01). Twenty-eight (68.3%) patients demonstrated an improvement in erectile dysfunction. Tumor size and invasiveness were significantly correlated with the improvement of erectile dysfunction. Preoperative testosterone <2.3 ng ml^-1 was an independent predictor of improvement in erectile dysfunction. In conclusion, our results indicated that tumor size and invasiveness were important factors affecting the improvement of sexual dysfunction in male patients with prolactinoma. The preoperative testosterone level was an independent predictor related to the improvement of erectile dysfunction.

Oophorectomy improves pituitary activin inhibitory function preventing lactotroph hyperplasia development

Among pituitary adenomas, prolactinomas are the most frequently diagnosed (about 50%). Dopamine agonists are generally effective in the treatment of prolactinomas. However, a subset of about 25% of patients does not respond to these agents. The management of drug-resistant prolactinomas remains a challenge for endocrinologists and new inhibitory treatments are needed. Pituitary activins inhibit lactotroph function. Its expression and action were found reduced in animal models of lactotroph hyperplasia (female mice overexpressing the B subunit of the human chorionic gonadotrophin and female mice knockout for dopamine receptor type 2). In these models, an oophorectomy avoids prolactinoma development. Hormonal replacement with oestradiol and/or progesterone is not enough to reach the tumor size observed in transgenic females. We postulated that the loss of gonadal inhibins after an oophorectomy contributes to prevent hyperplasia development. Here, we demonstrated that an oophorectomy at 2 months age recovers the following in adulthood: (i) pituitary activin expression, (ii) activin receptor expression specifically in lactotroph population, (iii) activin biological activity in lactotrophs with a concomitant reduction of Pit-1 expression. To summarize, when an oophorectomy is performed, inhibins are lost and the inhibitory action of pituitary activins on lactotroph population is recovered, helping to prevent lactotroph hyperplasia development. These results emphasize the importance of the inhibitory action of activins on lactotroph function, positioning activins as a good therapeutic target for the treatment of resistant prolactinomas.

Altered Connectivity of the Frontoparietal Network During Attention Processing in Prolactinomas

Prolactinomas have been reported for the failure of cognitive functions. However, the electrophysiological mechanisms of attention processing in prolactinomas remain unclear. In a visual mission, we monitored the scalp electroencephalography (EEG) of the participants. Compared with the healthy controls (HCs), larger frontoparietal theta and alpha coherence were found in the patients, especially in the right-lateralized hemisphere, which indicated a deficit in attention processing. Moreover, the frontoparietal coherence was positively correlated with altered prolactin (PRL) levels, implying the significance of PRL for adaptive brain compensation in prolactinomas. Taken together, this research showed the variations in attention processing between the HCs and prolactinomas. The coherence between frontal and parietal regions may be one of the possible electrophysiological biomarkers for detecting deficient attention processing in prolactinomas.

Stereotactic radiosurgery for secretory pituitary adenomas: systematic review and International Stereotactic Radiosurgery Society practice recommendations

OBJECTIVE

A systematic review was performed to provide objective evidence on the use of stereotactic radiosurgery (SRS) in the management of secretory pituitary adenomas and develop consensus recommendations.

METHODS

The authors performed a systematic review of the English-language literature up until June 2018 using the PRISMA guidelines. The PubMed (Medline), Embase, and Cochrane databases were searched. A total of 45 articles reporting single-institution outcomes of SRS for acromegaly, Cushing's disease, and prolactinomas were selected and included in the analysis.

RESULTS

For acromegaly, random effects meta-analysis estimates for crude tumor control rate, crude endocrine remission rate, and any new hypopituitarism rates were 97.0% (95% CI 96.0%-98.0%), 44.0% (95% CI 35.0%-53.0%), and 17.0% (95% CI 13.0%-23.0%), respectively. For Cushing's disease, random effects estimates for crude tumor control rate, crude endocrine remission rate, and any new hypopituitarism rate were 92.0% (95% CI 87.0%-95.0%), 48.0% (95% CI 35.0%-61.0%), and 21.0% (95% CI 13.0%-31.0%), respectively. For prolactinomas, random effects estimates for crude tumor control rate, crude endocrine remission rate, and any new hypopituitarism rate were 93.0% (95% CI 90.0%-95.0%), 28.0% (95% CI 19.0%-39.0%), and 12.0% (95% CI 6.0%-24.0%), respectively. Meta-regression analysis did not show a statistically significant association between mean margin dose with crude endocrine remission rate or mean margin dose with development of any new hypopituitarism rate for any of the secretory subtypes.

CONCLUSIONS

SRS offers effective tumor control of hormone-producing pituitary adenomas in the majority of patients but a lower rate of endocrine improvement or remission.

Microglial NLRP3 inflammasome activation-mediated inflammation promotes prolactinoma development

Prolactinomas have harmful effects on human health, and the pathogenesis is still unknown. Furthermore, 25% of prolactinoma patients do not respond to the therapy of dopamine receptor agonist in the clinic. Thus, it is important to reveal the pathogenesis and develop new therapeutic methods for prolactinomas. Herein, two animal models of prolactinomas, namely oestrogen-treated rats and transgenic D2 dopamine receptor-deficient mice, were used. PET/CT imaging detection showed that translocator protein-mediated microglia activation and inflammation significantly increased in the pituitary glands of prolactinomas rats. Messenger RNA microarrays were used to analyze and compare the differential gene and signal pathways of the pituitary glands between control and prolactinomas rats. Statistical results pertaining to gene enrichment showed that the innate immune response genes were upregulated in the pituitary glands of prolactinoma rats. This suggested that the innate immune response was activated. We analyzed the NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inflammasome that is one of the most important members of the innate immune system in mammals and found that the expressions of NLRP3, Caspase-1, apoptosis-associated speck-like, interleukin 1B (IL1B) and IL18 proteins of pituitary glands in prolactinomas rats were increased considerably compared with those in control rats. This suggested the activation of the NLRP3 inflammasome during the emergence and evolution of prolactinomas. Immunohistochemistry results also confirmed that the NLRP3 expression was elevated in human prolactinoma tissues, and the microglia marker-ionised calcium binding adaptor molecule-1 was co-located with the NLRP3 protein in prolactinomas by immunofluorescence assay. Finally, compared with the WT mice, NLRP3-/- mice had smaller pituitary glands (weight/body weight) and diminished prolactin (PRL) expressions and secretions. These findings were associated with a reduction in the caspase-1 activation and maturation of IL1B. Furthermore, MCC950 decreased the PRL expression and secretion following the inhibition of NLRP3 inflammasome activation in GH3 cells stimulated with lipopolysaccharide and nigericin. And MCC950 inhibited the pituitary tumor overgrowth and PRL expression and secretion in prolactinoma rats. These data confirm that the microglial NLRP3 inflammasome activation upregulates the inflammatory cytokines IL1/IL18 in the pituitary glands and induces prolactinomas. Our findings showed that microglial NLRP3 inflammasome activation-mediated IL1B-related inflammation promoted the development of prolactinomas and identified the inflammasome as a new therapeutic target for prolactinomas.

Resistance to Dopamine Agonists in Pituitary Tumors: Molecular Mechanisms

Pituitary neuroendocrine tumors (PitNET) are commonly benign tumors accounting for 10-25% of intracranial tumors. Prolactin-secreting adenomas represent the most predominant type of all PitNET and for this subtype of tumors, the medical therapy relies on the use of dopamine agonists (DAs). DAs yield an excellent therapeutic response in reducing tumor size and hormonal secretion targeting the dopamine receptor type 2 (D2DR) whose higher expression in prolactin-secreting adenomas compared to other PitNET is now well established. Moreover, although DAs therapy does not represent the first-line therapy for other PitNET, off-label use of DAs is considered in PitNET expressing D2DR. Nevertheless, DAs primary or secondary resistance, occurring in a subset of patients, may involve several molecular mechanisms, presently not fully elucidated. Dopamine receptors (DRs) expression is a prerequisite for a proper DA function in PitNET and several molecular events may negatively modify DR membrane expression, through the DRs down-regulation and intracellular trafficking, and DR signal transduction pathway. The current mini-review will summarise the presently known molecular events that underpin the unsuccessful therapy with DAs.

Outcomes of surgical and/or medical treatment in patients with prolactinomas during long-term follow-up: a retrospective single-centre study

OBJECTIVES

Prolactinoma is the most common cause of pituitary tumours. Current medical guidelines recommend dopamine agonists (cabergoline or bromocriptine) as the initial therapy for prolactinoma. However, surgical removal can also be considered in selected cases, such as patients with macroadenomas with local complications (bleeding or optic chiasm pressure) or those not responding to medical treatment.

METHODS

The present retrospective study included patients with prolactinomas (n=43; female, 24; male, 19) who were primarily managed with medical (n=32) or surgical (n=11) treatment.

RESULTS

Macroadenoma (n=29.67%) was commonly detected in both genders (female, 54%; male, 84%). Moreover, the mean pre-treatment prolactin levels were similar in both genders (female, 683.3 ± 1347 ng/mL; male, 685.4 ± 805 ng/mL; p=0.226). Surgically treated patients had a greater reduction in tumour size (27.7 ± 17.9 mm pre-treatment vs. 8.72 ± 14.2 mm post-treatment) than non-surgically treated ones (12.5 ± 7.5 mm pre-treatment vs. 4.1 ± 4.2 mm post-treatment; p=0.00). However, the decrease in prolactin levels was similar between the two patient groups (p=0.108). During the follow-up period (10.6 ± 7.0 years), the average cabergoline dose of the patients was 1.42 ± 1.47 mcg/week.

CONCLUSIONS

Although a surgical approach was considered for selected cases of prolactinoma, the average dose used for medical treatment was highly inadequate for the patients in the present study.

Effects of antiandrogens on prolactin levels among transgender women on estrogen therapy: A systematic review

BACKGROUND

Gender-affirming hormone therapy for transgender women includes estrogen and antiandrogens (cyproterone acetate, spironolactone, or gonadotropin-releasing hormone agonists). Both estrogen and antiandrogens are reported to increase prolactin levels. The objective is to systematically review the evidence of the effects of antiandrogens on prolactin levels, hyperprolactinemia, and prolactinomas among transgender women on estrogen therapy.

METHODS

We searched PubMed, Embase, and PsycInfo up to May 2020. We included studies with at least 3 months follow-up that evaluated the effects of antiandrogens among transgender women and reported on prolactin levels, hyperprolactinemia, or image-confirmed prolactinomas. Two reviewers independently screened studies for eligibility, serially abstracted data, and independently assessed risk of bias and graded strength of evidence.

FINDINGS

We included 17 studies (16 publications): 8 prospective cohorts, 8 retrospective cohorts, and 1 cross-sectional study, each with a moderate to serious risk of bias. Among transgender women on estrogen, prolactin levels increased by over 100% with cyproterone acetate and by up to 45% with spironolactone. However, we were unable to isolate the effects of antiandrogens from estrogen therapy. We were unable to draw conclusions about effects of antiandrogens on hyperprolactinemia and prolactinomas.

INTERPRETATION

Prolactin levels may be increased in transgender women who are taking both estrogens and an antiandrogen. Future research is needed to determine the effects of different antiandrogens on prolactin levels separately from estrogen therapy. Ideally, future studies would be prospective, provide either a comparison of two different antiandrogens or compare combination of estrogen and antiandrogen therapy to estrogen alone, and control for possible confounders.

mPRs represent a novel target for PRL inhibition in experimental prolactinomas

Membrane progesterone receptors are known to mediate rapid nongenomic progesterone effects in different cell types. Recent evidence revealed that mPRα is highly expressed in the rat pituitary, being primarily localized in lactotrophs, acting as an intermediary of P4-inhibitory actions on prolactin secretion. The role of mPRs in prolactinoma development remains unclear. We hypothesize that mPR agonists represent a novel tool for hyperprolactinemia treatment. To this end, pituitary expression of mPRs was studied in three animal models of prolactinoma. Expression of mPRs and nuclear receptor was significantly decreased in tumoral pituitaries compared to normal ones. However, the relative proportion of mPRα and mPRβ was highly increased in prolactinomas. Interestingly, the selective mPR agonist (Org OD 02-0) significantly inhibited PRL release in both normal and tumoral pituitary explants, displaying a more pronounced effect in tumoral tissues. As P4 also regulates PRL secretion indirectly, by acting on dopaminergic neurons, we studied mPR involvement in this effect. We found that the hypothalamus has a high expression of mPRs. Interestingly, both P4 and OrgOD 02-0 increased dopamine release in hypothalamus explants. Moreover, in an in vivo treatment, that allows both, pituitary and hypothalamus actions, the mPR agonist strongly reduced the hyperprolactinemia in transgenic females carrying prolactinoma. Finally, we also found and interesting gender difference: males express higher levels of pituitary mPRα/β, a sex that does not develop prolactinoma in these mice models. Taken together, these findings suggest mPRs activation could represent a novel tool for hyperprolactinemic patients, especially those that present resistance to dopaminergic drugs.

[Cerebrospinal fluid rhinorrhea in primary treatment of large and giant prolactinomas with dopamine agonists]

At present, pharmacological therapy of prolactinomas with dopamine agonists (DAs) is considered the treatment of choice. In most cases, giant prolactinomas respond to treatment with dopamine agonists and decrease in size during the first months of the treatment. One of the rare but dangerous complications of conservative treatment of prolactinomas with invasive growth is cerebrospinal fluid rhinorrhea.

MATERIAL AND METHODS

We present a retrospective analysis of 15 patients with macropropactinomas who underwent surgery for cerebrospinal fluid rhinorrhea developed due to primary therapy with dopamine agonists at the Burdenko Neurosurgical Institute (BNI) in the period between 2005 and 2015. All patients had large and giant tumors (according to the classification adopted at the BNI). When cerebrospinal fluid rhinorrhea was detected, patients were hospitalized to the BNI for examination, detection of a CSF fistula, reconstruction of a defect, and resection (if possible) of the tumor.

RESULTS

In the period between 2005 and 2015, 15 patients (8 males and 7 females) with prolactinomas of a large and giant size at the onset of conservative therapy underwent surgery for cerebrospinal fluid rhinorrhea at the BNI. All patients underwent transnasal reconstruction of a skull base defect, with 13 out of 15 patients undergoing simultaneous resection of the tumor. After tumor resection, reconstruction was performed using auto-fat, fascia, and glue (in 8 cases). In the remaining cases, apart from auto-fat, fascia, and glue, a mucoperiosteal flap and auto-bone were used. Fourteen patients were followe-up. In 13 cases, there was no relapse of cerebrospinal fluid rhinorrhea after skull base reconstruction. In 1 case, there was a relapse of cerebrospinal fluid rhinorrhea.

CONCLUSION

Conservative treatment of patients with giant prolactinomas should be performed under regular control of ENT doctors and neurosurgeons for timely detection and surgical treatment of cerebrospinal fluid rhinorrhea.

Neuropsychiatric and metabolic aspects of dopaminergic therapy: perspectives from an endocrinologist and a psychiatrist

The dopaminergic treatment represents the primary treatment in prolactinomas, which are the most common pituitary adenomas and account for about 40% of all pituitary tumours with an annual incidence of six to ten cases per million population. The dopaminergic treatment includes ergot and non-ergot derivatives with high affinity for the dopamine receptors D1 or/and D2. Through the activation of the dopaminergic pathway on pituitary lactotrophs, the dopamine agonists inhibit the prolactin synthesis and secretion, therefore normalizing the prolactin levels and restoring eugonadism, but they also lead to tumour shrinkage. Treatment with dopamine agonists has been associated - apart from the common side effects such as gastrointestinal symptoms, dizziness and hypotension - with neuropsychiatric side effects such as impulse control disorders (e.g. pathological gambling, compulsive shopping, hypersexuality and binge eating) and also with behavioral changes from low mood, irritability and verbal aggressiveness up to psychotic and manic symptoms and paranoid delusions not only in patients with prolactinomas but also in patients with Parkinson's disease and restless leg syndrome. They usually have de novo onset after initiation of the dopaminergic treatment and have been mainly reported in patients with Parkinson's disease, who are being treated with higher doses of dopamine agonists. Moreover, dopamine and prolactin seem to play an essential role in the metabolic pathway. Patients with hyperprolactinemia tend to have increased body weight and an altered metabolic profile with hyperinsulinemia and increased prevalence of diabetes mellitus in comparison to healthy individuals and patients with non-functioning pituitary adenomas. Treatment with dopamine agonists in these patients in short-term studies seems to lead to weight loss and amelioration of the metabolic changes. Together these observations provide evidence that dopamine and prolactin have a crucial role both in the regard and metabolic system, findings that merit further investigation in long-term studies.

Phosphorylation of kinase insert domain receptor by cyclin-dependent kinase 5 at serine 229 is associated with invasive behavior and poor prognosis in prolactin pituitary adenomas

Pituitary adenomas constitute 15-20% of intracranial neoplasms. Previously we reported that cyclin-dependent kinase 5 (CDK5) is upregulated in pituitary tumors associated with activating protein p35, and plays an essential role in pituitary adenomas progression. Here we explored the mechanisms of CDK5 signaling in prolactin pituitary adenomas. Our data indicate that p35 expression and CDK5 activity are both significantly increased in human invasive prolactin pituitary adenomas as compared to noninvasive forms of pituitary adenomas. Inhibition of CDK5 activity suppressed cell migration and invasive ability in GH3 rat pituitary cells. We identified that CDK5 phosphorylates serine 229 residue (Ser-229) of kinase insert domain receptor (KDR), also known as VEGFR-2, in prolactin pituitary adenomas. Phosphorylation of Ser-229 is required for proper KDR surface localization. Phosphorylated Ser-229 in KDR (pSer-229) levels are significantly higher in noninvasive and invasive prolactin pituitary adenomas compared to normal pituitary tissues. In addition, our data indicated that higher KDR pSer-229 correlates with worse prognosis in patients with prolactin pituitary adenomas. In summary, our results illustrated that CDK5-mediated KDR phosphorylation controls prolactin pituitary adenoma progression and KDR pSer-229 serves as a potential prognostic biomarker for both noninvasive and invasive pituitary adenomas.

Cognitive Function and Serum Hormone Levels Are Associated with Gray Matter Volume Decline in Female Patients with Prolactinomas

Background and objective

Cognitive impairments have been reported in patients with hyperprolactinemia; however, there is a lack of knowledge of brain structure alterations relevant to hyperprolactinemia in prolactinomas. Thus, we aimed to identify changes in brain structure in prolactinomas and to determine whether these changes are related to cognitive performance and clinical characteristics.

Methods

Participants were 32 female patients with prolactinomas and 26 healthy controls (HC) matched for age, sex, education, and handedness. All participants underwent magnetic resonance imaging brain scans, neuropsychological assessments, and clinical evaluations. Voxel-based morphometry analysis was used to identify changes in gray matter volume (GMV). Partial correlation analysis and multiple linear regression were performed to determine the relationship between GMV, cognition, and clinical characteristics.

Results

Compared to HC, patients with prolactinomas demonstrated a decrease in GMV in the left hippocampus, left orbitofrontal cortex, right middle frontal cortex (MFC), and right inferior frontal cortex (IFC). In addition, patients performed worse than controls on tests for verbal memory and executive function, and this was significantly related to the GMV of the left hippocampus and right MFC, respectively. Moreover, in the patients, we found a negative relationship between serum prolactin levels and the GMV of the left hippocampus and right IFC, whereas a positive relationship was found between the GMV of the left hippocampus and serum levels of estradiol and luteinizing hormone.

Conclusion

In patients with prolactinomas, specific brain structure abnormalities have been identified and are associated with cognitive impairments and dysfunctional hormones. This study enhances our understanding of brain structure changes that may occur with prolactinomas and provides novel and fundamental evidence for previous behavioral findings relevant to hyperprolactinemia.

The Mechanism and Pathways of Dopamine and Dopamine Agonists in Prolactinomas

Dopamine agonists such as bromocriptine and cabergoline are the predominant treatment drugs for prolactinoma by inhibiting prolactin secretion and shrinking tumor size. However, the pathways of either dopamine or its agonists that lead to the death of cells are incompletely understood and some are even conflicting conclusions. The main aim of this paper is to review the different pathways of dopamine and its agonists in prolactinomas to help to gain a better understanding of their functions and drug resistance mechanisms.

Role of prolactin/adenoma maximum diameter and prolactin/adenoma volume in the differential diagnosis of prolactinomas and other types of pituitary adenomas

The present study aimed to investigate the function of the prolactin/adenoma maximum diameter (PRL/MD) and the prolactin/adenoma volume (PRL/V) in the differential diagnosis of prolactinomas and other types of pituitary adenomas. A total of 118 patients with pituitary adenoma, hyperprolactinemia and a plasma PRL <250 µg/l were enrolled. Clinical data from these patients were retrospectively analyzed. A receiver operating characteristic curve was plotted. The function of PRL, PRL/MD and PRL/V in the differential diagnosis of prolactinomas and other types of pituitary adenomas was compared. The results revealed that a PRL of 55.65 µg/l was the most accurate [sensitivity (SE), 0.800; specificity (SP), 0.716; positive predictive value (PPV), 0.857; negative predictive value (NPV), 0.933; and Youden index (YI), 0.516]. The PRL/MD with the highest diagnostic value was 4.03 µg/(l × mm) (SE, 0.800; SP, 0.898; PPV, 0.727; NVP, 0.929; and YI, 0.698). The PRL/V with the highest diagnostic value was 54.00 µg/(l × cm³) (SE, 0.900; SP, 0.966; PPV, 0.900; NVP, 0.966; and YI, 0.866). The PRL/MD tended to be of higher diagnostic accuracy than PRL, but this difference was not statistically significant (P=0.097). The differentiation ability of PRL/V was significantly stronger than that of PRL (P=0.028). Thus, serum PRL, PRL/MD and PRL/V levels may be able to differentiate prolactinomas from other types of hyperprolactinemia-causing pituitary adenomas prior to treatment. PRL/V may be better than the PRL level in achieving a differential diagnosis, and the optimal PRL/V ratio for differentiating prolactinomas from other types of hyperprolactinemia-causing pituitary adenomas was 54.00 µg/(l × cm³).

MicroRNA-9 regulates fetal alcohol-induced changes in D2 receptor to promote prolactin production

Fetal alcohol exposure (FAE) is known to increase prolactin (PRL) secretion from the pituitary lactotropes. In this study, we determined whether microRNAs (miRs) are involved in FAE-induced alteration in PRL release. We employed a rat animal model of FAE involving feeding pregnant Fisher 344 rats with a liquid diet containing 6.7% alcohol between gestational days 7-21 (AF). Both cyclic and estradiol-implanted FAE females showed increased levels of plasma PRL and pituitary Prl mRNA but reduced levels of pituitary dopamine D2 receptor (D2r) and its short spliced form (D2s). FAE increased the expression levels of miR-9 and miR-326 and did not produce any significant changes in miR-153 or miR-200a levels in the pituitary. Effects of FAE on miR-9 and miR-326 were associated with reduced levels of D2r and D2s, increased levels of Prl in the pituitary, and in plasma. These effects of FAE on D2r, D2s and Prl were enhanced following estradiol treatment. In PRL-producing MMQ cells, ethanol increased miR-9 but not miR-326, reduced levels of D2r and D2s and increased levels of Prl Treatment of MMQ cells with an anti-miR-9 oligo reduced ethanol effects on miR-9, D2r, D2s and Prl miR-9 mimic oligos reduced the luciferase activity of reporter vector containing D2r 3'UTR, but failed to reduce the mutant luciferase activity. These data suggest that FAE programs the pituitary to produce increased amounts of miR-9 expression that represses the D2r gene and its spliced variant D2s by targeting its 3'UTR leading to an increase in PRL production and secretion.

[Indications for surgical treatment of prolactin-secreting pituitary adenomas]

Prolactinomas account for about 40% of all pituitary adenomas. The main treatment for prolactinomas is undoubtedly therapy with dopamine agonists (DAs). However, prolonged conservative treatment (for many years or even throughout life) that is necessary for permanent control of the disease makes some patients refuse pharmacological treatment for various reasons. In addition, not all prolactinomas respond to DAs therapy. Sometimes, the patient is not able to continue treatment because of the severity of side effects. Along with tumor resistance to therapy and patient intolerance of DAs, complications (liquorrhea, hemorrhage in the tumor) may occur during conservative treatment. In these cases, surgery is necessary. The paper analyzes the modern literature on various treatment options for prolactin-secreting pituitary adenomas and defines the indications for surgical treatment.

Challenges and controversies in the treatment of prolactinomas

Recent studies have reported a higher prevalence of pituitary tumors than previously thought. Among these tumors, prolactinomas occur in up to 66% of cases. Since the mid-1980s, the widespread use of dopamine agonists has facilitated the management of the majority of prolactinomas, allowing biological and tumoral control in most cases. The less frequent cases of resistant prolactinomas remain challenging despite a multimodal therapy approach. The understanding of genetic alterations in familial and aggressive pituitary tumors provides new perspectives in the management of some prolactinomas. Genetic screening should be considered, particularly in familial cases but also in young patients with macroprolactinomas, as some mutations can predict potential aggressiveness.

Crosstalk between tumor blood vessels heterogeneity and hormonal profile of pituitary adenomas: evidence and controversies

AIM

Pituitary adenomas are intracranial tumors with controversial histopathology and heterogeneous clinical behaviour. Angiogenesis and tumor blood vessels' role in pathogenesis, remain one of the great pituitary tumor mysteries. No connection between tumor vessel heterogeneity, hormonal profile and biological behaviour has been reported. We aimed to study pituitary adenomas blood vessels concerning their immature, intermediate or mature phenotype and microvessel density, correlated with immunohistochemical hormonal profile and hormone values in serum and cerebrospinal fluid.

MATERIALS AND METHODS

We classified pituitary adenomas according to hormone profile and we applied a double immunostaining highlighting both endothelial and perivascular cells for a more accurate assessment of blood vessel types.

RESULTS

Overall microvessel density was found to be highest in growth hormone-secreting adenomas (48.51 ± 12.15) and lowest in prolactinomas (29.15 ± 18.78). When we differentially counted tumor blood vessels we observed a predominance of immature and intermediate blood vessels compared to mature ones. A significant correlation was found between immature tumor blood vessels and tissue prolactin expression, as assessed by immunhistochemistry (p=0.044). A partial correlation was found between serum (p=0.036) and cerebrospinal prolactin values (p=0.006) with immature and intermediate blood vessels. Also, a partial correlation has been reported only between mature blood vessels and cerebrospinal fluid prolactin values (p=0.008). No correlation was obtained for other types of pituitary adenomas.

CONCLUSION

Our results suggest a strong involvement of prolactin with a dual role in pituitary adenomas vasculature remodelling by acting both on endothelial and perivascular cells, a finding that could partially explain discrepancies between clinical diagnosis and hormonal profile.

Hyperprolactinemia

Prolactin (PRL) is an anterior pituitary hormone which has its principle physiological action in initiation and maintenance of lactation. In human reproduction, pathological hyperprolactinemia most commonly presents as an ovulatory disorder and is often associated with secondary amenorrhea or oligomenorrhea. Galactorrhea, a typical symptom of hyperprolactinemia, occurs in less than half the cases. Out of the causes of hyperprolactinemia, pituitary tumors may be responsible for almost 50% of cases and need to be investigated especially in the absence of history of drug induced hyperprolactinemia. In women with hyperprolactinemic amenorrhea one important consequence of estrogen deficiency is osteoporosis, which deserves specific therapeutic consideration. Problem in diagnosing and treating hyperprolactinemia is the occurrence of the ‘big big molecule of prolactin’ that is biologically inactive (called macroprolactinemia), but detected by the same radioimmunoassay as the biologically active prolactin. This may explain many cases of very high prolactin levels sometimes found in normally ovulating women and do not require any treatment. Dopamine agonist is the mainstay of treatment. However, presence of a pituitary macroadenoma may require surgical or radiological management.

Improving Quality of Life in Patients with Pituitary Tumours

Evaluation of health-related quality of life (QoL) in people with pituitary tumours has received much attention over the last 10-15 years. Most of them show impaired QoL, but little is known about how to prevent impairment or how to improve QoL. Our aim is to review what is known about QoL in pituitary tumours patients and to highlight the areas worth improving, for the patient's well being. The article has four sections: acromegaly, Cushing's syndrome, prolactinomas and non-functioning adenomas. Control of comorbidities is usually an important factor to prevent QoL impairment; however, each disease has specific characteristics that should be properly addressed in order to obtain full patient recovery after successful therapy.

Pituitary surgery for small prolactinomas as an alternative to treatment with dopamine agonists

Despite the fact that consensus guidelines recommend long-term dopamine agonist (DA) therapy as a first-line approach to the treatment of small prolactinoma, some patients continue to prefer a primary surgical approach. Concerns over potential adverse effects of long-term medical therapy and/or the desire to become pregnant and avoid long-term medication are often mentioned as reasons to pursue surgical removal. In this retrospective study, 34 consecutive patients (30 female, 4 male) preferably underwent primary pituitary surgery without prior DA treatment for small prolactinomas (microprolactinoma 1-10 mm, macroprolactinoma 11-20 mm) at the Department of Neurosurgery, University of Bern, Switzerland. At the time of diagnosis, 31 of 34 patients (91%) presented with symptoms. Patients with microprolactinomas had significantly lower preoperative prolactin (PRL) levels compared to patients with macroprolactinomas (median 143 μg/l vs. 340 μg/l). Ninety percent of symptomatic patients experienced significant improvement of their signs and symptoms upon surgery. The postoperative PRL levels (median 3.45 μg/l) returned to normal in 94% of patients with small prolactinomas. There was no mortality and no major morbidities. One patient suffered from hypogonadotropic hypogonadism after surgery despite postoperative normal PRL levels. Long-term remission was achieved in 22 of 24 patients (91%) with microprolactinomas, and in 8 of 10 patients (80%) with macroprolactinomas after a median follow-up period of 33.5 months. Patients with small prolactinomas can safely consider pituitary surgery in a specialized centre with good chance of long-term remission as an alternative to long-term DA therapy.

Alteration in G proteins and prolactin levels in pituitary after ethanol and estrogen treatment

BACKGROUND

Chronic administration of ethanol increases plasma prolactin levels and enhances estradiol's mitogenic action on the lactotropes of the pituitary gland. The present study was conducted to determine the changes in the pituitary levels of G proteins during the tumor development following alcohol and ethanol treatments.

METHODS

Using ovariectomized Fischer-344 female rats, we have determined ethanol and estradiol actions at 2 and 4 weeks on pituitary weight and pituitary cell contents of prolactin, Gs. Gq11, Gi1, Gi2, and Gi3 proteins. Western blots were employed to measure protein contents.

RESULTS

Ethanol increased basal and estradiol-enhanced wet weight and the prolactin content in the pituitary in a time-dependent manner. Chronic exposure of estradiol increased the levels of Gs protein in the pituitary. Unlike estradiol, ethanol exposure did not show significant effect on the basal level of Gs protein, but moderately increased the estradiol-induced levels of this protein. Estradiol exposure enhanced Gq11 protein levels in the pituitary after 2 and 4 weeks, while ethanol treatment failed to alter these protein levels in the pituitary in control-treated or estradiol-treated ovariectomized rats. In the case of Gi1, estradiol but not ethanol increased the level of this protein at 4 weeks of treatment. However, estradiol and ethanol alone reduced the levels of both Gi2 and Gi3 proteins at 2 and 4 weeks of treatment. Ethanol also significantly reduced the estradiol-induced Gi2 levels at 4 weeks and Gi3 level at 2 and 4 weeks.

CONCLUSIONS

These results confirm ethanol's and estradiol's growth-promoting and prolactin stimulating actions on lactotropes of the pituitary and further provide evidence that ethanol and estradiol may control lactotropic cell functions by altering expression of specific group of G proteins in the pituitary.

[Sex hormone receptors in pituitary prolactinomas]

An attempt was made to interpret the mechanism responsible for the occurrence of pituitary tumors - prolactinoma in persons of different sex. The presence or absence of androgenic receptors in the tumors was studied. Analysis of the concentration of nuclear receptors, estrogen ones in particular, showed their higher concentration in prolactin-positive pituitary adenomas than in inactive pituitary adenomas. Androgen receptors were detected in the gonadotropic and lactotropic cells of the Intact pituitary. Analysis of the concentration of nuclear testosterone receptors in different morphological types of pituitary adenomas revealed no differences in the luteinizing hormone/follicle-stimulating hormone-positive and prolactin-positive tumors.

Potential of gene therapy for the treatment of pituitary tumors

Pituitary adenomas constitute the most frequent neuroendocrine pathology, comprising up to 15% of primary intracranial tumors. Current therapies for pituitary tumors include surgery and radiotherapy, as well as pharmacological approaches for some types. Although all of these approaches have shown a significant degree of success, they are not devoid of unwanted side effects, and in most cases do not offer a permanent cure. Gene therapy-the transfer of genetic material for therapeutic purposes-has undergone an explosive development in the last few years. Within this context, the development of gene therapy approaches for the treatment of pituitary tumors emerges as a promising area of research. We begin by presenting a brief account of the genesis of prolactinomas, with particular emphasis on how estradiol induces prolactinomas in animals. In so doing, we discuss the role of each of the recently discovered growth inhibitory and growth stimulatory substances and their interactions in estrogen action. We also evaluate the cell-cell communication that may govern these growth factor interactions and subsequently promote the growth and survival of prolactinomas. Current research efforts to implement gene therapy in pituitary tumors include the treatment of experimental prolactinomas or somatomammotropic tumors with adenoviral vector-mediated transfer of the suicide gene for the herpes simplex type 1 (HSV1) thymidine kinase, which converts the prodrug ganciclovir into a toxic metabolite. In some cases, the suicide transgene has been placed under the control of pituitary cell-type specific promoters, like the human prolactin or human growth hormone promoters. Also, regulatable adenoviral vector systems are being assessed in gene therapy approaches for experimental pituitary tumors. In a different type of approach, an adenoviral vector, encoding the human retinoblastoma suppressor oncogene, has been successfully used to rescue the phenotype of spontaneous pituitary tumors of the pars intermedia in mice. We close the article by discussing the future of molecular therapies. We point out that although, gene therapy represents a key step in the development of molecular medicine, it has inherent limitations. As a consequence, it is our view that at some point, genetic therapies will have to move from exogenous gene transfer (i.e. gene therapy) to endogenous gene repair. This approach will call for radically new technologies, such as nanotechnology, whose present state of development is outlined.