Prolactin is a polypeptide hormone which mainly acts on the reproductive system and plays an important role in penile erection and ejaculation. Prolactin receptors have a variety of short forms apart from the classic long form, which are widely expressed in male reproductive glands. High levels of prolactin can induce erectile dysfunction and results in secondary male infertility, which are mainly associated with the inhibition of dopaminergic activity, reduction of the testosterone level, and contraction of the cavernous smooth muscle. Moreover, low levels of prolactin can result in ejaculatory dysfunction. This article updates the views on the expressions of prolactin receptors in the male reproductive system, the effects of prolactin on penile erection and ejaculation, and its action mechanisms.
Ejaculation ; physiology ; Erectile Dysfunction ; Humans ; Infertility, Male ; Male ; Muscle, Smooth ; physiopathology ; Penile Erection ; physiology ; Prolactin ; physiology ; Receptors, Prolactin ; physiology ; Reproduction

The incidence of risperidone-induced amenorrhea has not been well known. Since conven tional antipsyrchotics-induced amenorrhea may be due to the hyperprolactinemia associated with the block of dopamine D2 receptor, it seems justified to expect that risperidone having the affinities far dopamine and serotonin receptor also may induce the hyperprolactinemia and the amenorrhea. We report the case of risperidone-induced amenorrhea in a premenopausal woman with schizophrenia. The amenorrhea of the patient would be related to the hyperprolactinemia. Clinicians should be vigilant to the possible reaction in their female patients with schizophrenia.
Amenorrhea* ; Dopamine ; Female ; Humans ; Hyperprolactinemia ; Incidence ; Prolactin ; Receptors, Dopamine D2 ; Risperidone ; Schizophrenia* ; Serotonin

Blonanserin is a newly developed agent which is approved for the treatment of schizophrenia in Japan and Korea. This agent has high affinity to dopamine D2 receptor and serotonin 5-HT2A receptor. Blonanserin was as effective as risperidone in the treatment of schizophrenia, and showed greater efficacy in negative symptoms than haloperidol. Blonanserin was well tolerated in both the short- and long-term studies, and the frequency and intensity of EPS is generally similar with risperidone. For other side effects, blonanserine seems to have better safety profiles compared with other atypicals, and showed less prolactin elevation than risperidone. These findings suggest that blonanserin is useful in the treatment of schizophrenia.
Haloperidol ; Japan ; Korea ; Piperazines ; Piperidines ; Prolactin ; Receptor, Serotonin, 5-HT2A ; Receptors, Dopamine D2 ; Risperidone ; Schizophrenia ; Serotonin

As comparing to typical antipsychotics, atypical antipsychotics have several characters such as no causing catalepsy in animal models or extrapyramidal side effects in schizophrenia patients, no or transient prolactin elevation (except risperidone, amisulpride), effects on negative symptoms, mood and affective symptoms, and efficacy in refractory schizophrenia. In views of the results of several studies so far achieved, the action at the dopamine D2/3 receptors, is by itself, sufficient to provide the contemporary kind of atypical antipsychotic activity. This review will attempt to address the modulation of dopamine D2 receptors as a basis of atypical antipsychotic action by looking over dopamine receptor occupancy, differential effects at the striatal versus extrastriatal dopamine D2 receptor, D2 receptor affinity and Koff consideration, effects for psychotic symptoms.
Affective Symptoms ; Antipsychotic Agents ; Catalepsy ; Dopamine* ; Humans ; Models, Animal ; Prolactin ; Receptors, Dopamine ; Receptors, Dopamine D2* ; Risperidone ; Schizophrenia

OBJECTIVES: This study was aimed to investigate the association between amisulpride-induced hyperprolactinemia and the Taq1A polymorphism in the D2 dopamine receptor gene (DRD2) in schizophrenic patients. METHODS: The plasma concentrations of prolactin were measured before and after treatment with amisulpride in one hundred and twenty-five schizophrenic patients. The effect of the Taq1A variants of the DRD2 on the risk of amisulpride-induced hyperprolac-tinemia was the main the outcome measure. The genotyping for Taq1A (rs1800497) polymorphism was performed using TaqMan single nucleotide polymorphism (SNP) genotyping assay. RESULTS: There was a significant difference between the prolactin level at baseline and the 6th week after treatment with amisulpride in all the subjects. However, there were no significant correlations between ΔProlactin (the difference between prolactin level at baseline and the 6th week after treatment) and the Taq1A genotypes. CONCLUSIONS: This is the first study to investigate the-correlations between the Taq1A polymorphism and the amisulpride-induced hyperprolactinemia in Korean schizophrenic patients. The current results suggested the further large-scale researches on various SNPs in the DRD2 gene will establish clear goals and provide answers to the unanswered questions described in this study.
Dopamine* ; Genotype ; Humans ; Hyperprolactinemia* ; Outcome Assessment (Health Care) ; Plasma ; Polymorphism, Single Nucleotide ; Prolactin ; Receptors, Dopamine ; Receptors, Dopamine D2* ; Schizophrenia*

BACKGROUND: Hyperprolactinemia has been linked with hyperandrogenism and hirsutism in some women. High plasma Dihydroandrosterone and DHA-S levels were reported in patients with hyperprolactinemia and a dissociation of adrenal androgen and cortisol secretion occurs in normal subjects. The mechanism has not been elucidated, but it has been suggested that pituitary factors other than ACTH modulate adrenal androgen synthesis, One candidate hormone is prolactin. Adrenal tissue has been found to possess prolactin receptors and prolactin has been shown to act synergistically with ACTH and lowers the activity of the enzyme 5a-reductase or 3B-hydroxysteroid dehydrogenase (3B-HSD). The aim of this study was to investigate the secretion of adrenal androgen metabolites in patients with idiopathic hyperprolactinemia and prolactinoma and to deterrnine the relationship with prolactin and androgens. METHODS: We measured 24 hour-urinary DHEA, androstenedione, androsterone, pregnenolone, tetrahydrocorticoid and cortisol in 16 normal controls and 5 patients with idiopathic hyperprolac-tinemia (HP) and 12 patients with prolactonoma in the early follicular phase. RESULTS: Urinary DHEA, AD (androsteredione), and androsterone, the metabolites of adrenal androgen, were significantly higher in both patients with idiopathic HP and prolactinoma compared with those in normal controls (p<0.05), whereas they were not different in both disease groups. Urinary pregnenolone levels, early metabolite of adrenal steroid synthesis, were lower in patients. In contrast, urinary tetrahydorcortisol and cortisol were higher in patients compared to controls. There was no difference in DHEA:androsterone ratio between patients and controls. And there were no correlation between prolactin levels and the levels of androgenic metabolites or clinical symptoms. CONCLUSION: Prolactin has a tropic effct on the secretion of androgens and steroids by the adrenal cortex. But prolactin levels were not correlated with androgen levels or clinical symptoms (amenorrhea), and it might have little effect on lowering the activity of 3B-HSD.
Adrenal Cortex ; Adrenocorticotropic Hormone ; Androgens ; Androstenedione ; Androsterone ; Dehydroepiandrosterone ; Female ; Follicular Phase ; Hirsutism ; Humans ; Hydrocortisone ; Hyperandrogenism ; Hyperprolactinemia* ; Oxidoreductases ; Plasma ; Pregnenolone ; Prolactin ; Prolactinoma ; Receptors, Prolactin ; Steroids

OBJECTIVETo investigate the correlation of prolactin receptor (PRL-R) expression to estrogen receptor (ER) and progesterone receptor (PR) expressions in primary breast cancer.

METHODSFor 130 female patients with breast cancer (median age 46 years), PRL-R expression in the primary tumor was detected by immunohistochemistry, and the correlation between PRL-R and ER/PR expressions was analyzed statistically.

RESULTSPRL-R positivity in the primary tumor was found in 89 of the patients (68.5%), and the positivity rate for PRL-R was positively correlated to ER expression (P<0.05). Further stratification of the patients according to the CerbB-2 status revealed such a correlation only in CerbB-2-positive patients (P<0.05). In the patient cohort, no significant correlation was found in the positivity rate between PRL-R and PR expressions (P>0.05), but in CerbB-2-positive patients, the positivity rate of PRL-R showed a positive correlation to PR expression (P<0.05).

CONCLUSIONThe positive correlations in positivity rate between the PRL-R and ER/PR expressions are found only in CerbB-2 positive patients with breast cancer, and the expressional status of CerbB-2 affects the correlation between PRL-R and ER/PR expression in breast cancer.

Adult ; Aged ; Breast Neoplasms ; metabolism ; Female ; Humans ; Middle Aged ; Receptor, ErbB-2 ; genetics ; metabolism ; Receptors, Estrogen ; metabolism ; Receptors, Progesterone ; metabolism ; Receptors, Prolactin ; metabolism

OBJECTIVETo investigate the effect of acupuncture on progesterone (P4) and prolactin (PRL) in rats of embryo implantation dysfunction (EID).

METHODSOn the first day of pregnancy, 72 female Wistar rats were randomly allocated into the normal group, the EID model group, the acupuncture group and the P4 group (18 in each group). The normal group was injected sesame oil, while the other three groups were given mifepristone to establish the EID model. The acupuncture group and the P4 group were given treatment of acupuncture and P4 injection, respectively. The serum of P4 and PRL were detected by radioimmunoassay, and the mRNA and protein expressions of P4 receptor (PR) and PRL receptor (PRLR) were detected using real-time polymerase chain reaction and immunohistochemical method, respectively.

RESULTSCompared with the normal group, the serum levels of P4 and PRL as well as the mRNA and protein expression levels of PR and PRLR in the EID model group were significantly lowered (P<0.01 or P<0.05). The above indices in the acupuncture group and the P4 group were significantly elevated compared with the EID model group (P<0.01 or P<0.05).

CONCLUSIONAcupuncture can promote embryo implantation effectively, which might be related to the effects of acupuncture on upregulating the P4 and PRL levels in serum and the PR and PRLR expression levels in rats.

Acupuncture Therapy ; Animals ; Embryo Implantation ; Endometrium ; metabolism ; Female ; Gene Expression Regulation ; Immunohistochemistry ; Male ; Pituitary Gland ; metabolism ; Pregnancy ; Progesterone ; blood ; Prolactin ; blood ; RNA, Messenger ; genetics ; metabolism ; Rats, Wistar ; Receptors, Progesterone ; genetics ; metabolism ; Receptors, Prolactin ; genetics ; metabolism

Normal and abnormal follicular growth and steroidogenesis depend on gonadotropins as well as intraovarian peptides, which may mediate or potentiate gonadotropin action. Inhibin also affect follicular development and steroidogenesis and may play a role in dominant follicle selection and follicular atresia. Therefore, we studied the differences of serum inhibin, gonadotropin and androgen levels in the women with only the ultrasound findings and no disorder, and polycystic ovary (PCO) with ovulatory disturbance. We prospectively analysed forty-three women with PCO. The diagnosis of PCO was based on typical appearance of the ovaries on TVS. Twelve women with regular menstrual cycle and normal ovarian morphology were selected as control. Basal levels of inhibin, luteinizing hormone(LH), follicle stimulating hormone(FSH), estradiol(E2), testosterone(T), androstenedione(ADD), dehydroepiandrosterone-sulfate(DS), prolactin and TSH in serum were determined. There were significant differences in basal LH levels and LH/FSH ratio between the control and the women with PCO. The basal levels of inhibin and E2 in the oligo-amenorrheic PCO (N=34) were significantly higher than those in the control. There was higher negative correlation between the inhibin and T levels in the oligo-amenorrheic PCO, but, not in the regular cycling PCO. Also, there was higher positive correlation between the LH and T levels in the oligo-amenorrheic PCO, but not in the regular cycling PCO. These data presume that the initial event of PCO is elevated pituitary LH secretion. Elevated levels of LH may down-regulate LH receptors on granulosa cells and also cause hypertrophy of the thecal layer. High level of androgen secreted by the hypertrophied thermal layer may stimulate inhibin secretion from granulosa cells and can be converted to estrogen by extraovarian tissues and could serve to augment pituitary sensitivity to GnRH with a resultant secretion of more LH follicular development and dominant follicle selection resulted in ovulatory disturbance.
Diagnosis ; Estrogens ; Female ; Follicular Atresia ; Gonadotropin-Releasing Hormone ; Gonadotropins ; Granulosa Cells ; Humans ; Hypertrophy ; Inhibins* ; Lutein ; Menstrual Cycle ; Ovary* ; Peptides ; Prolactin ; Prospective Studies ; Receptors, LH ; Ultrasonography

In our previous study, we demonstrated that immobilization stress blocked estrogen-induced luteinizing hormone(LH) surge possibly by inhibiting the synthesis and release of gonadotropin-releasing hormone (GnRH) at the hypothalamic level and by blocking estrogen-induced prolactin (PRL) surge by increasing the synthesis of dopamine receptor at the pituitary level in ovariectomized rats. The present study was performed to determine whether immobilization stress affects pituitary LH responsiveness to GnRH, and whether endogenous opioid peptide (EOP) and dopamine systems are involved in blocking LH and PRL surges during immobilization stress. Immobilization stress was found to inhibit basal LH release and to completely abolish LH surge. However, the intravenous application of GnRH agonist completely restored immobilization-blocked LH surge and basal LH release. Treatment with naloxone did not exert any effect on immobilization-blocked LH surge but increased basal LH release during immobilization stress. Pimozide did not affect immobilization-blocked LH surge or basal LH release. Naloxone also decreased immobilization-induced basal PRL release, but had no effect on immobilization-blocked PRL surge. Immobilization-increased basal PRL levels were augmented by pimozide treatment and immobilization-blocked PRL surge was dramatically restored by pimozide. We conclude that immobilization stress does not impair pituitary LH response to GnRH, and that the immobilization stress-induced blockage of LH surge is probably not mediated by either the opioidergic or the dopaminergic system. However, immobilization-blockade of PRL surge may be partly mediated by the dopaminergic system.
Animal ; Estradiol/*pharmacology ; Female ; Gonadorelin/*pharmacology ; Immobilization ; Luteinizing Hormone/*secretion ; Naloxone/pharmacology ; Opioid Peptides/physiology ; Ovariectomy ; Prolactin/*secretion ; Rats ; Rats, Sprague-Dawley ; Receptors, Dopamine/physiology ; Stress/*metabolism