Risk of Breast Cancer With Prolactin Elevating Antipsychotic Drugs: An Observational Study of US Women (Ages 18-64 Years).

PURPOSE/BACKGROUND: Antipsychotic drugs are well established to alter circulating prolactin levels by blocking dopamine D2 receptors in the pituitary. Prolactin activates many genes important in the development of breast cancer. Prior studies have found an association with antipsychotic use and risk of breast cancer. METHODS/PROCEDURES: The IBM MarketScan Commercial and Medicaid Databases were used to establish a large, observational cohort of women taking antipsychotics drugs compared with anticonvulsants or lithium. A new user design was used that required 12 months of insurance enrollment before the first antipsychotic or anticonvulsant/lithium prescription. Invasive breast cancer was identified using diagnostic codes. Multivariable Cox proportional hazards models were used to evaluate the risk of breast cancer with antipsychotic drug exposure controlling for age and other risk factors. FINDINGS/RESULTS: A total of 914 cases (0.16%) of invasive breast cancer were identified among 540,737 women. Exposure to all antipsychotics was independently associated with a 35% increased risk of breast cancer (aHR [adjusted hazard ratio], 1.35; 95% confidence interval, 1.14-1.61). Category 1 drugs (high prolactin) were associated with a 62% increased risk (aHR, 1.62; 95% CI, 1.30-2.03), category 2 drugs a 54% increased risk (aHR, 1.54; 95% CI, 1.19-1.99), and category 3 drugs were not associated with breast cancer risk. IMPLICATIONS/CONCLUSIONS: In the largest study of antipsychotics taken by US women, a higher risk between antipsychotic drug use and increased risk for breast cancer was observed, with a differential higher association with antipsychotic categories that elevate prolactin. Our study confirms other recent observational studies of increased breast cancer risk with antipsychotics that elevate prolactin.

Prolactin Response to Metformin in Cabergoline-Resistant Prolactinomas: A Pilot Study.

INTRODUCTION: Cabergoline is the treatment of choice for prolactinomas. However, 10-20% of prolactinomas are resistant to cabergoline. Metformin, a biguanide widely used in the treatment of diabetes mellitus, has been shown to reduce prolactin secretion in various pituitary tumor-cell lineages both in vitro and in vivo and in human pituitary adenomas in vitro. The aim of this study is to test the effects of metformin addition to cabergoline treatment on prolactin levels in patients with resistant prolactinomas. SUBJECTS AND METHODS: This is a prospective study performed in an outpatient clinic in a reference center. Ten adult patients (26-61 years) with prolactinomas (7 M), persistent hyperprolactinemia (38-386 ng/mL) under cabergoline treatment (2-7 mg/week) for at least 6 months (6-108 months), features of metabolic syndrome, and not taking metformin were included. Metformin (1.0-2.5 g v.o./day) was given according to patients' tolerance. Cabergoline doses were kept unchanged. Serum prolactin levels were measured before and after short- (30-60 days) and long-term (120-180 days) metformin treatment. RESULTS: Mean prolactin levels did not show any significant changes (148 ± 39 vs. 138 ± 42 vs. 133 ± 39 ng/mL, before, at 30-60 days, and at 120-180 days, respectively, p = 0.196) after metformin (mean dose: 1.25 g/day; range: 1.0-2.0 g/day). No patient reached a normal prolactin level during metformin treatment. Two patients were considered partial responders for exhibiting prolactin decreases ≥50% at a single time point during metformin. CONCLUSION: Metformin addition to ongoing high-dose cabergoline treatment in patients with cabergoline-resistant prolactinomas failed to show a consistent inhibitory effect in serum prolactin levels.

Prolactin signaling modulates stress-induced behavioral responses in a preclinical mouse model of migraine.

OBJECTIVE: The aim of this study was to determine if prolactin signaling modulates stress-induced behavioral responses in a preclinical migraine model. BACKGROUND: Migraine is one of the most complex and prevalent disorders. The involvement of sex-selective hormones in migraine pathology is highly likely as migraine is more common in women and its frequency correlates with reproductive stages. Prolactin has been shown to be a worsening factor for migraine. Normally prolactin levels are low; however levels can surge during stress. Dopamine receptor agonists, which suppress pituitary prolactin release, are an effective migraine treatment in a subset of patients. Previously, we showed that administration of prolactin onto the dura mater induces female-specific behavioral responses, suggesting that prolactin may play a sex-specific role in migraine. METHODS: The effects of prolactin signaling were assessed using a preclinical migraine model we published recently in which behavioral sensitization is induced by repeated stress. Plasma prolactin levels were assessed in naïve and stressed CD-1 mice (n = 3-5/group) and transgenic mice with conditional deletion of the Prlr in Nav1.8-positive sensory neurons (Prlr conditional knock-out [CKO]; n = 3/group). To assess the contribution of prolactin release during stress, naïve or stressed male and female CD-1 mice were treated with the prolactin release inhibitor bromocriptine (2 mg/kg; n = 7-12/group) or vehicle for 5 days (8-12/group) and tested for facial hypersensitivity following stress. Additionally, the contribution of ovarian hormones in regulating the prolactin-induced responses was assessed in ovariectomized female CD-1 mice (n = 6-10/group). Furthermore, the contribution of Prlr activation on Nav1.8-positive sensory neurons was assessed. Naïve or stressed male and female Prlr CKO mice and their control littermates were tested for facial hypersensitivity (n = 8-9/group). Immunohistochemistry was used to confirm loss of Prlr in Nav1.8-positive neurons in Prlr CKO mice. The total sample size is n = 245; the full analysis sample size is n = 221. RESULTS: Stress significantly increased prolactin levels in vehicle-treated female mice (39.70 ± 2.77; p < 0.0001). Bromocriptine significantly reduced serum prolactin levels in stressed female mice compared to vehicle-treated mice (-44.85 ± 3.1; p < 0.0001). Additionally, no difference was detected between female stressed mice that received bromocriptine compared to naïve mice treated with bromocriptine (-0.70 ± 2.9; p = 0.995). Stress also significantly increased serum prolactin levels in male mice, although to a much smaller extent than in females (0.61 ± 0.08; p < 0.001). Bromocriptine significantly reduced serum prolactin levels in stressed males compared to those treated with vehicle (-0.49 ± 0.08; p = 0.002). Furthermore, bromocriptine attenuated stress-induced behavioral responses in female mice compared to those treated with vehicle (maximum effect observed on day 4 post stress [0.21 ± 0.08; p = 0.03]). Bromocriptine did not attenuate stress-induced behavior in males at any timepoint compared to those treated with vehicle. Moreover, loss of ovarian hormones did not affect the ability of bromocriptine to attenuate stress responses compared to vehicle-treated ovariectomy mice that were stressed (maximum effect observed on day 4 post stress [0.29 ± 0.078; p = 0.013]). Similar to CD-1 mice, stress increased serum prolactin levels in both Prlr CKO female mice (27.74 ± 9.96; p = 0.047) and control littermates (28.68 ± 9.9; p = 0.041) compared to their naïve counterparts. There was no significant increase in serum prolactin levels detected in male Prlr CKO mice or control littermates. Finally, conditional deletion of Prlr from Nav1.8-positive sensory neurons led to a female-specific attenuation of stress-induced behavioral responses (maximum effect observed on day 7 post stress [0.32 ± 0.08; p = 0.007]) compared to control littermates. CONCLUSION: These data demonstrate that prolactin plays a female-specific role in stress-induced behavioral responses in this preclinical migraine model through activation of Prlr on sensory neurons. They also support a role for prolactin in migraine mechanisms in females and suggest that modulation of prolactin signaling may be an effective therapeutic strategy in some cases.

Vitamin D status determines the impact of metformin on circulating prolactin levels in premenopausal women.

WHAT IS KNOWN AND OBJECTIVE: Metformin was found to normalize secretory function of overactive pituitary cells. Its effect on circulating thyrotropin levels was more pronounced in women receiving exogenous vitamin D. The aim of the current study was to investigate whether vitamin D status determines the impact of metformin on prolactin levels in premenopausal women with hyperprolactinaemia. METHODS: The study population consisted of three groups of women with prediabetes and elevated prolactin levels: vitamin D-naïve women with vitamin D insufficiency (group 1; n = 19), women receiving vitamin D preparations because of vitamin D deficiency (group 2 n = 20), as well as vitamin D-naïve women with normal vitamin D status (group 3 n = 23). All participants were then treated with metformin (2.55-3 g daily). Circulating levels of glucose, insulin, prolactin, thyrotropin, free thyroid hormones, gonadotropins, estradiol, calcium and 25-hydroxyvitamin were determined at baseline and six months later. RESULTS AND DISCUSSION: At baseline, prolactin levels were higher in group 1 than in the remaining groups of patients. Although metformin decreased glucose levels and improved insulin sensitivity in all treatment groups, this effect was more pronounced in groups 2 and 3. Only in subjects with 25-hydroxyvitamin D levels within the reference range, metformin reduced prolactin levels. The impact on prolactin levels correlated with 25-hydroxyvitamin D levels and with the improvement in insulin sensitivity. The drug produced a neutral effect on circulating levels of thyrotropin, free thyroid hormones, gonadotropins, estradiol, calcium and 25-hydroxyvitamin D. WHAT IS NEW AND THE CONCLUSION: The results of the current study suggest that the impact of metformin on secretory function of overactive lactotropes depends on the vitamin D status of patients.

The impact of metformin on prolactin levels in postmenopausal women.

WHAT IS KNOWN AND OBJECTIVE: Metformin-induced reduction in prolactin levels is more pronounced in users of hormonal contraception than in non-users. The current study was aimed at investigating whether physiological concentrations of estradiol determine the impact of metformin on lactotrope secretory function. METHODS: We studied two matched groups of postmenopausal women with elevated prolactin levels. Twenty-three women were on hormone replacement therapy (group 1), while the remaining ones (group 2, n = 23) did not use sex hormones. Because of coexistent prediabetes, all individuals received metformin (2.55-3 g daily) for the following six months. Circulating levels of total prolactin, monomeric prolactin, thyrotropin, gonadotropins, free thyroid hormones and estradiol were determined at the beginning and at the end of the study. RESULTS AND DISCUSSION: Compared with group 1, group 2 was characterized by higher gonadotropin levels and lower estrogen levels. Although metformin reduced monomeric prolactin levels in both study groups, this effect was more pronounced in group 1 than in group 2. Only in group 1, metformin decreased total prolactin levels, while only in group 2 the drug reduced FSH levels. Metformin treatment did not affect circulating levels of the remaining hormones. The impact of metformin on total and monomeric prolactin levels correlated with baseline prolactin levels and with the degree of improvement in insulin sensitivity. WHAT IS NEW AND CONCLUSION: The obtained results indicate that the impact of metformin on lactotrope secretory function is partially determined by the estrogen status of patients.

Prolactin ordering patterns in psychiatric inpatients and the impact this has on patient management.

OBJECTIVE: Guidelines stipulate that baseline prolactin be ordered prior to commencing antipsychotic treatment to facilitate investigation of any subsequent hyperprolactinaemic symptoms. The aim was to observe when and why prolactin levels are ordered for psychiatry inpatients commencing or continuing antipsychotics and how this alters clinical management. METHODS: Psychiatry inpatients admitted to the Alfred Hospital, Melbourne, Australia, in 2018 with the diagnoses of psychosis, schizophrenia, schizo-affective disorder or bipolar affective disorder were retrospectively analysed. Results and clinical history data were collected in patients in whom prolactin was ordered during or within 12 months of the relevant admission. RESULTS: Of 592 patients admitted during this period, 90 had prolactin ordered. Eight (8.9%) of the 90 tests were for hyperprolactinaemic symptoms, while the remainder were routine blood work. The results altered clinical management in 10 of the 90 (11.1%) patients. Of these 10, 8 were symptomatic. In the six patients with first episode psychosis, only one had prolactin ordered prior to antipsychotic commencement. CONCLUSIONS: Adherence to guideline recommendations of baseline prolactin testing was poor. When established on antipsychotics, measuring prolactin rarely changed management in asymptomatic patients; however, it did in those with hyperprolactinaemic symptoms. Measuring prolactin in asymptomatic patients on antipsychotics appears unhelpful.

Effects of milking frequency and domperidone injections on milk production and prolactin signaling in the mammary gland of dairy cows.

Eleven mid-lactation Holstein cows were milked twice daily during the first 2 experimental weeks. During wk 3 to 10, the cows were differentially milked: right quarters were milked thrice daily (3×) and left quarters were milked once daily (1×). During wk 11 to 14, all quarters were milked twice daily. After 4 wk of differential milking, the cows received daily i.m. injections of the dopamine antagonist domperidone (DOMP; 300 mg; n = 6) or of dimethyl sulfoxide as the control (CTL; n = 5) for 8 wk (wk 7-14). During the differential milking period (wk 3-6), milk production was greater for quarters milked 3× than for those milked 1× but did not differ between DOMP and CTL cows. During the differential milking + injection period (wk 7-10), milk production continued to differ according to milking frequency. However, DOMP injection did not have an effect or interact with milking frequency on milk production. During the injection period (wk 11-14), milk production remained greater in the quarters previously milked 3× and milk production increased in DOMP injected cows but not in CTL cows. Injections of DOMP increased prolactin concentration, which was greater in the serum of DOMP cows than in that of CTL cows during the differential milking + injection and the injection periods. The expression of genes that are directly related to milk synthesis (CSN2, LALBA, and ACACA) was greater in the 3× quarters than in the 1× quarters. In addition, DOMP increased CSN2 expression during the injection period. The expression of both isoforms of the PRLR gene was greater in the 3× quarters during the differential milking + injection and the injection periods. At the protein level, injections of DOMP tended to increase the number of long PRLR isoform during the differential milking + injection period. The number of short PRLR isoform was greater in the 1× quarters than in the 3× quarters during the differential milking, the differential milking + injection, and the injection periods. The total amount of STAT3 protein was greater in the 1× quarters during the differential milking and the differential milking + injection periods. The amount of phosphorylated STAT3 protein was greater in the 1× quarters during the differential milking period. The total amount of phosphorylated STAT5 protein was greater in the 3× quarters during the differential milking and the differential milking + injection periods. The results of this experiment support the hypothesis that the responsiveness of the mammary gland to PRL is modulated by milking frequency, although the underlying mechanism remains to be determined.

Myostatin regulates pituitary development and hepatic IGF1.

Circulating myostatin-attenuating agents are being developed to treat muscle-wasting disease despite their potential to produce serious off-target effects, as myostatin/activin receptors are widely distributed among many nonmuscle tissues. Our studies suggest that the myokine not only inhibits striated muscle growth but also regulates pituitary development and growth hormone (GH) action in the liver. Using a novel myostatin-null label-retaining model (Jekyll mice), we determined that the heterogeneous pool of pituitary stem, transit-amplifying, and progenitor cells in Jekyll mice depletes more rapidly after birth than the pool in wild-type mice. This correlated with increased levels of GH, prolactin, and the cells that secrete these hormones, somatotropes and lactotropes, respectively, in Jekyll pituitaries. Recombinant myostatin also stimulated GH release and gene expression in pituitary cell cultures although inhibiting prolactin release. In primary hepatocytes, recombinant myostatin blocked GH-stimulated expression of two key mediators of growth, insulin-like growth factor (IGF)1 and the acid labile subunit and increased expression of an inhibitor, IGF-binding protein-1. The significance of these findings was demonstrated by smaller muscle fiber size in a model lacking myostatin and liver IGF1 expression (LID-o-Mighty mice) compared with that in myostatin-null (Mighty) mice. These data together suggest that myostatin may regulate pituitary development and function and that its inhibitory actions in muscle may be partly mediated by attenuating GH action in the liver. They also suggest that circulating pharmacological inhibitors of myostatin could produce unintended consequences in these and possibly other tissues.

Submaximal doses of ghrelin do not inhibit gonadotrophin levels but stimulate prolactin secretion in postmenopausal women.

OBJECTIVE: An inhibitory effect of ghrelin on gonadotrophin secretion has been reported in normally menstruating women possibly modulated by endogenous oestrogen. The aim of this study was to examine the effect of ghrelin on gonadotrophin and prolactin (PRL) secretion in oestrogen-deprived postmenopausal women. DESIGN: Prospective intervention study. PATIENTS AND MEASUREMENTS: Ten healthy postmenopausal volunteer women were studied during two 15-days periods of oestrogen treatment (A and B) a month apart. Four experiments (Exp) were performed in total, two on day 1 (Exp 1A and Exp 1B) and two on day 15 (Exp 15A and Exp 15B) of the two periods. The women received in Exp 1A and in Exp 15A two iv injections of ghrelin (0.15 µg/kg at time 0 minute and 0.30 µg/kg at time 90 minutes) and in Exp1B and in Exp 15B normal saline (2 mL), respectively. Blood samples were taken at -15, 0, 30, 60, 90, 120, 150 and 180 minutes. RESULTS: After oestrogen treatment, late follicular phase serum oestradiol levels were attained on day 15 of periods A and B. Ghrelin administration did not affect serum levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), whereas it increased significantly those of growth hormone (GH) and PRL. In Exp 15A, serum PRL increment in response to ghrelin (area under the curve, net increment) was significantly greater than in Exp 1A (P<.05). CONCLUSIONS: This study demonstrates for the first time that in oestrogen-deprived postmenopausal women, ghrelin administration affects neither FSH nor LH levels but stimulates PRL secretion, that is amplified by exogenous oestrogen administration.

Pituitary response profile following metoclopramide administration in women with different forms of hyperprolactinemia.

AIMS: To test the hypothesis that macroprolactinemia is an extra-pituitary phenomenon by showing that the pituitary production of prolactin in patients with hyperprolactinemia due to macroprolactin is comparable to that in normoprolactinemic women and different from that in women with monomeric hyperprolactinemia. METHODS: Twenty-five women were studied: eight with macroprolactin hyperprolactinemia, eight with monomeric hyperprolactinemia, and nine controls. Prolactin levels were measured before and after precipitation with polyethylene glycol at baseline and at 5, 10,15, 30, and 60 min after metoclopramide administration (10 mg i.v.) in the three groups. RESULTS: The response profile of total and monomeric prolactin following the administration of metoclopramide was similar in women with monomeric hyperprolactinemia and normoprolactinemia but different in women with macroprolactinemia. The areas under the curve for total and monomeric prolactin were higher in patients with macroprolactinemia than in the other two groups (p < 0·0001). The maximal concentration of monomeric prolactin was reached before that of total prolactin in macroprolactinemic patients but the differences were not significant. DISCUSSION: Our findings support the hypothesis that prolactin secretion is comparable in women with macroprolactinemia and in normoprolactinemic women. The dynamics of the secretion suggest that the formation of prolactin complexes is an extra-pituitary process.

Differential Effects of Cyproterone Acetate vs Spironolactone on Serum High-Density Lipoprotein and Prolactin Concentrations in the Hormonal Treatment of Transgender Women.

INTRODUCTION: Spironolactone and cyproterone acetate (CPA) are the two main antiandrogen medications used in feminizing hormone therapy in transgender women. Previous studies have suggested that these two agents might have opposite effects on high-density lipoprotein (HDL) level when used in this context, and limited data have suggested CPA increases prolactin more than spironolactone. AIM: To compare the effects of spironolactone and CPA on HDL and prolactin serum concentrations in transgender women. METHODS: A retrospective chart review was conducted at three clinical sites in Toronto, Ontario, Canada. Patients were selected if they (i) identified as a transgender woman, (ii) had newly started spironolactone or CPA with estrogen or restarted spironolactone or CPA after a washout period of at least 6 months, and (iii) had not used other antiandrogens within the previous 6 months. MAIN OUTCOME MEASURES: HDL and prolactin concentrations between the two treatment groups at baseline and at 12 months. RESULTS: Eighty-two patients were included in the spironolactone group and 31 patients were included in the CPA group. Baseline HDL and prolactin levels were not significantly different between the two groups. At 12 months, HDL increased by 0.10 mmol/L (SD = 0.24) in the spironolactone group but decreased by 0.07 mmol/L (SD = 0.21) in the CPA group (P = .002). The difference remained significant after adjusting for baseline HDL, use of lipid-lowering drugs, and age. The change in prolactin was +3.10 µg/L (SD = 5.70) in the spironolactone group and +11.8 µg/L (SD = 8.63) in the CPA group (P < 0.001). This difference also remained significant after adjusting for baseline prolactin level. CONCLUSION: These data suggest that spironolactone use in transgender women increases HDL levels and that CPA has the opposite effect. CPA also is associated with a larger increase in prolactin. These factors should be considered when choosing between these two antiandrogen agents.

Effects of tibolone and its metabolites on prolactin and insulin-like growth factor binding protein-1 expression in human endometrial stromal cells.

The effects of the postmenopausal replacement steroid tibolone and its 3α-, 3ß-OH and Δ-4 tibolone metabolites were evaluated on progesterone receptor-mediated classic decidualization markers insulin-like growth factor binding protein-1 (IGFBP-1) and prolactin expression in human endometrial stromal cells (HESCs). Supernatants of conditioned medium or erxtracted RNA from experimental cell incubations of confluent HESCs were subjected to ELISAs, Western blot analysis and RT/PCR, and results were statisically assesed. Over 21 days, specific ELISAs observed linear increases in secreted IGFBP-1 and prolactin levels elicited by tibolone and its metabolites. Cultured HESCs were refractory to E2 and dexamethasone, whereas tibolone and each metabolite exceeded medroxyprogesterone acetate in significantly elevating IGFBP-1 and prolactin output. Anti-progestins eliminated IGFBP-1 and prolactin induction by tibolone and its metabolites. Immunoblotting and RT/PCR confirmed ELISA results. These observations of IGFBP-1 and prolactin expression: (a) indicate the relevance of cultured HESCs in evaluating the chronic effects of tibolone administration to women; (b) are consistent with PR-mediated endometrial atrophy and protection against endometrial bleeding despite the persistence of circulating ER-binding, but not PR-binding metabolites following tibolone administration to women.

Acute and chronic effects of kisspeptin-54 administration on GH, prolactin and TSH secretion in healthy women.

BACKGROUND: The peptide hormone kisspeptin is essential for human reproduction, acting on the hypothalamus to stimulate gonadotrophin-releasing hormone (GnRH) secretion. Kisspeptin is currently being evaluated as a novel therapeutic for women with infertility. However, some animal studies suggest that kisspeptin may also stimulate growth hormone (GH), prolactin and thyroid-stimulating hormone (TSH) secretion, with implications for its safety; no previous study has investigated whether kisspeptin stimulates these pituitary hormones in humans. AIM: To determine whether kisspeptin-54 modulates GH, prolactin and TSH secretion in healthy women. DESIGN AND PARTICIPANTS: Prospective, single-blinded, placebo-controlled, one-way crossover study. Five healthy women received 7 days of twice-daily subcutaneous bolus vehicle (month 1) or 6·4 nmol/kg kisspeptin-54 (month 2). MEASUREMENTS: Serum samples were analysed post hoc for GH, prolactin and TSH. RESULTS: Mean serum GH, PRL and TSH did not change during the first 4 h following kisspeptin-54 injection when compared with vehicle. The mean frequency or amplitude of GH pulses (which influence GH function) did not change acutely following kisspeptin-54 injection when compared with vehicle. No chronic changes in serum GH, PRL or TSH were observed over the 7-day period of twice-daily kisspeptin-54 injections when compared with vehicle. CONCLUSION: While we cannot exclude any effect of kisspeptin-54 on GH, prolactin or TSH secretion, we observed no significant changes in these hormones at a dose of kisspeptin-54 administration known to stimulate gonadotrophin secretion in a small study of healthy women. These data have important implications for the potential of kisspeptin to treat patients with infertility.

Childhood maltreatment affects the serotonergic system in male alcohol-dependent individuals.

BACKGROUND: Reduced central serotonergic neurotransmission has been demonstrated in individuals with excessive alcohol consumption and/or alcohol dependence. Childhood maltreatment has also been found to have a negative impact on central serotonergic neurotransmission. The aim of this study was to evaluate the impact of childhood maltreatment on central serotonergic dysfunction in alcohol-dependent individuals. METHODS: Adult men with a diagnosis of alcohol dependence (n = 18) were recruited from outpatient treatment units for alcoholism. Central serotonergic neurotransmission was assessed by a neuroendocrine method, that is, the prolactin (PRL) response to the selective 5-HT reuptake inhibitor citalopram. Childhood maltreatment was assessed retrospectively by the Childhood Trauma Questionnaire. RESULTS: Alcohol-dependent individuals with childhood experience of emotional abuse had significantly lower PRL response compared with those without such abuse (3 ± 5 and 64 ± 24 mU/l, respectively; t = 6.51, p < 0.001). Among those who reported childhood emotional abuse, 4 of 7 individuals had flat PRL responses in comparison with none in those with no report of such abuse (p < 0.01). CONCLUSIONS: This is the first study to show that self-reported childhood maltreatment, in particular emotional abuse, in male alcohol-dependent individuals is associated with a quite dramatic (more than 90%) reduction in central serotonergic neurotransmission. It should, however, be noted that the number of individuals is relatively small, and the results should therefore be considered as preliminary.

Short-term effects of high-dose khat on sperm parameters and reproductive hormonal levels in olive baboons (Papio anubis).

The biological effects of khat (Catha edulis) on reproduction and fertility are inadequately investigated and controversial, hence we determined the effects of oral administration of high-dose khat on sperm parameters and male hormonal levels in olive baboons. In this study, 6 male baboons received a high dose of khat (500 g/week) during 1 month. Electroejaculation for sperm studies (concentration, motility and chromatin integrity) and plasma collection for hormonal analysis (testosterone, prolactin and cortisol) were done weekly during 1 month before and 1 month during khat administration as well as 2 weeks after the last dose of khat administration. Administration of khat extract induced a significant reduction in sperm motility (p = 0.008), sperm count (p = 0.041), sperm chromatin integrity (p = 0.0003), testosterone levels (p = 0.035) and prolactin levels (p = 0.0115), but not in cortisol levels and sperm volume (p > 0.05). The results suggest that high-dose khat decreases sperm quality and testosterone and hence may contribute to male infertility.

Potential role of prolactin in antipsychotic-mediated association of schizophrenia and type 2 diabetes.

It remains unclear why atypical antipsychotics confer a risk for hyperglycemia compared to typical antipsychotics. Atypical antipsychotics antagonize dopamine receptors-2 (D(2)) and serotonin (5-HT) receptors-2, while typical antipsychotics antagonize only D(2) receptors. We aimed at elucidating the mechanistic differences between the role of typical and atypical antipsychotics on prolactin levels and glucose regulation. A Medline search was conducted during 2010 using the search terms type 2 diabetes (T2D), typical/atypical antipsychotics, schizophrenia, prolactin, and serotonin. We discuss the effect of typical and atypical antipsychotics on prolactin levels and glucose regulation. Given that prolactin is under negative control by dopamine and positive control by serotonin, typical antipsychotics induce elevations in prolactin, while atypical antipsychotics do not. Research studies show protective effects of prolactin on T2D. We hypothesize that the difference in induction of T2D between typical and atypical antipsychotics is due to the antipsychotic receptor binding mediated effect in changes in prolactin levels.

Serotonergic function and treatment of behavioral and psychological symptoms of frontotemporal dementia.

OBJECTIVES: The purposes of this study were first, to evaluate the effectiveness of citalopram in treating behavioral disturbances in frontotemporal dementia (FTD) subjects and second, to determine whether an association exists between serotonergic function, as determined by a neuroendocrine challenge, and treatment response. DESIGN: Single-dose citalopram (30 mg per os) challenge followed by a 6-week open-label study. SETTING: Outpatients referred to memory clinics. PARTICIPANTS: Fifteen patients suffering from FTD with severe behavioral and psychological symptoms of dementia. INTERVENTION: Following citalopram challenge, all patients were treated with citalopram titrated to a target dose of 40 mg once daily. MEASUREMENTS: Behavioral disturbances, using the Neuropsychiatric Inventory (NPI) (primary outcome) and Frontal Behavioural Inventory (secondary outcome), were assessed. Change in prolactin concentration following citalopram challenge was used as an index of central serotonergic response. RESULTS: Citalopram treatment was effective in treating behavioral symptoms, with significant decreases in NPI total score (F[2, 28] = 6.644, p = 0.004), disinhibition (F[2, 28] = 4.030, p = 0.029), irritability (F[2, 28] = 7.497, p = 0.003) and depression (F[2, 28] = 3.467, p = 0.045) scores over the 6 weeks. Significant improvement in Frontal Behavioural Inventory scores suggested that citalopram was also effective in the treatment ofbehaviors specific to FTD. A lower change score in concentration of prolactin was significantly positively correlated with greater improvement in the total NPI score from baseline to endpoint (r = 0.687, p = 0.005). A blunted response to a citalopram challenge, implying a dysfunctional serotonergic system, predicted a more positive treatment outcome. CONCLUSIONS: The results suggest that despite the endogenous serotonin deficiency of FTD, citalopram treatment may be effective in targeting the behavioral disturbances characteristic of FTD.

Randomized pilot study of cabergoline, a dopamine receptor agonist: effects on body weight and glucose tolerance in obese adults.

AIM: Dopaminergic hypofunction and hyperprolactinaemia have been implicated in the pathogenesis of obesity and glucose intolerance. The aim of this pilot study was to determine the efficacy of cabergoline, a dopamine receptor agonist, on body weight and glucose tolerance in obese non-diabetic persons with normal plasma prolactin levels. METHODS: This 16-week double blind, placebo-controlled pilot study randomized non-diabetic obese adults (body mass index 30-42 kg/m(2) ) to placebo or cabergoline (0.25 mg twice weekly for 4 weeks followed by 0.5 mg twice weekly for the next 12 weeks). Of 40 subjects enrolled, 29 completed 16 weeks: 16 randomized to placebo and 13 to cabergoline. All subjects were counselled on a 500 kcal/day calorie deficit diet. A 75-g oral glucose tolerance test was performed at baseline and at 16 weeks. RESULTS: As expected, prolactin levels decreased after cabergoline (p < 0.001). Weight loss was similar after placebo compared with cabergoline treatment: 1.0 vs. 1.2% body weight, respectively. Fasting glucose levels did not differ between groups after treatment, however, 90-min postprandial glucose and insulin decreased in the cabergoline group only (p = 0.029). HOMA-IR (homeostasis model of assessment) increased by 40% after placebo and 1.5% after cabergoline treatment. CONCLUSIONS: This pilot study suggests that cabergoline therapy may improve glucose tolerance independent of weight loss, however, a larger, longer term study of dopamine receptor agonist therapy in obese individuals is warranted to confirm this finding.

Effect of the antipsychotic agent amisulpride on glucose lowering and insulin secretion.

AIMS: To investigate the effects of the second generation antipsychotic (R/S)-amisulpride, and the chirally purified enantiomers, on glucose homeostasis in diet-induced obese (DIO) mice. METHODS: Normal and DIO mice were treated with pharmacologically relevant doses of amisulpride prior to oral glucose tolerance tests (OGTTs). Blood glucose, insulin, glucagon-like peptide-1, prolactin and amisulpride drug levels were determined. RESULTS: Racemic amisulpride significantly reduced glucose excursions during OGTT in both normal and DIO mice. This potent effect was preserved with the 'off-isomer', R-amisulpride (ED(50) 1 mg/kg). Insulin secretion was significantly increased with R-amisulpride with only a minor increase in prolactin levels. CONCLUSIONS: Amisulpride has antidiabetic actions in DIO mice resulting from increased insulin secretion. This provides some explanation for why amisulpride, unlike other atypical antipsychotics, is not diabetogenic in man. Furthermore, the observation that R-amisulpride is also antidiabetic and has minimal impact on prolactin levels presents the opportunity for development of this isomer as an antidiabetic agent.