The prolactin secretory response to neuroleptic drugs: mechanisms, applications and limitations

Antipsychotics: Mechanisms underlying clinical response and side-effects and novel treatment approaches based on pathophysiology

Antipsychotic drugs are central to the treatment of schizophrenia and other psychotic disorders but are ineffective for some patients and associated with side-effects and nonadherence in others. We review the in vitro, pre-clinical, clinical and molecular imaging evidence on the mode of action of antipsychotics and their side-effects. This identifies the key role of striatal dopamine D2 receptor blockade for clinical response, but also for endocrine and motor side-effects, indicating a therapeutic window for D2 blockade. We consider how partial D2/3 receptor agonists fit within this framework, and the role of off-target effects of antipsychotics, particularly at serotonergic, histaminergic, cholinergic, and adrenergic receptors for efficacy and side-effects such as weight gain, sedation and dysphoria. We review the neurobiology of schizophrenia relevant to the mode of action of antipsychotics, and for the identification of new treatment targets. This shows elevated striatal dopamine synthesis and release capacity in dorsal regions of the striatum underlies the positive symptoms of psychosis and suggests reduced dopamine release in cortical regions contributes to cognitive and negative symptoms. Current drugs act downstream of the major dopamine abnormalities in schizophrenia, and potentially worsen cortical dopamine function. We consider new approaches including targeting dopamine synthesis and storage, autoreceptors, and trace amine receptors, and the cannabinoid, muscarinic, GABAergic and glutamatergic regulation of dopamine neurons, as well as post-synaptic modulation through phosphodiesterase inhibitors. Finally, we consider treatments for cognitive and negative symptoms such dopamine agonists, nicotinic agents and AMPA modulators before discussing immunological approaches which may be disease modifying. This article is part of the issue entitled 'Special Issue on Antipsychotics'.

Drugs and prolactin

Medications commonly cause hyperprolactinemia and their use must be differentiated from pathologic causes. The most common medications to cause hyperprolactinemia are the antipsychotic agents, although some of the newer atypical antipsychotics do not do so. Other medications causing hyperprolactinemia include antidepressants, antihypertensive agents, and drugs which increase bowel motility. Often, the medication-induced hyperprolactinemia is symptomatic, causing galactorrhea, menstrual disturbance, and erectile dysfunction. In the individual patient, it is important differentiate hyperprolactinemia due to a medication from a structural lesion in the hypothalamic-pituitary area. This can be done by stopping the medication temporarily to determine if the prolactin (PRL) levels return to normal, switching to another medication in the same class which does not cause hyperprolactinemia (in consultation with the patient's physician and/or psychiatrist), or by performing an MRI or CT scan. If the hyperprolactinemia is symptomatic, management strategies include switching to an alternative medication which does not cause hyperprolactinemia, using estrogen/testosterone replacement, or cautiously adding a dopamine agonist.

Clinical implications of antipsychotic-induced hyperprolactinemia in patients with schizophrenia spectrum or bipolar spectrum disorders: recent developments and current perspectives

Hyperprolactinemia is increasingly studied as a frequent and potentially important consequence of antipsychotic medication treatment. Some individuals presenting with hyperprolactinemia remain asymptomatic, but others may exhibit a wide range of clinical symptoms resulting from either the direct effects of prolactin on body tissues (galactorrhea, gynecomastia) or endocrine-related secondary effects (sexual and reproductive dysfunction in the short term, and possibly the risk of tumorigenesis and osteoporosis in the longer term). Short-term side effects may negatively impact medication compliance, and long-term effects have the potential for serious health consequences. Antipsychotic medications have differing propensities to cause prolactin elevation. The first-generation antipsychotics, as well as the second-generation antipsychotic risperidone and its active metabolite paliperidone, have been shown to cause marked and sustained elevations in prolactin levels, whereas others of the second-generation antipsychotics appear to have little or no effect on prolactin levels or may decrease prolactin. A comprehensive overview of antipsychotics and hyperprolactinemia is presented together with a review of emerging evidence about the short- and long-term health risks of hyperprolactinemia.

Medication-induced hyperprolactinemia

Medication use is a common cause of hyperprolactinemia, and it is important to differentiate this cause from pathologic causes, such as prolactinomas. To ascertain the frequency of this clinical problem and to develop treatment guidelines, the medical literature was searched by using PubMed and the reference lists of other articles dealing with hyperprolactinemia due to specific types of medications. The medications that most commonly cause hyperprolactinemia are antipsychotic agents; however, some newer atypical antipsychotics do not cause this condition. Other classes of medications that cause hyperprolactinemia include antidepressants, antihypertensive agents, and drugs that increase bowel motility. Hyperprolactinemia caused by medications is commonly symptomatic, causing galactorrhea, menstrual disturbance, and impotence. It is Important to ensure that hyperprolactinemia in an Individual patient is due to medication and not to a structural lesion in the hypothalamic/pituitary area; this can be accomplished by (1) stopping the medication temporarily to determine whether prolactin levels return to normal, (2) switching to a medication that does not cause hyperprolactinemia (in consultation with the patient's psychiatrist for psychoactive medications), or (3) performing magnetic resonance imaging or computed tomography of the hypothalamic/pituitary area. If the patient's hyperprolactinemia is symptomatic, treatment strategies include switching to an alternative medication that does not cause hyperprolactinemia, using estrogen or testosterone replacement, or, rarely, cautiously adding a dopamine agonist.

Diagnosis and management of pituitary tumors: recent advances

In recent years, the medical therapy for prolactinomas and GH-secreting adenomas has greatly improved due to the availability of new, highly effective, long-acting dopamine and somatostatin analogues. Although medical therapy has for some time been the first-line approach to prolactinoma management, the incidence of patients requiring surgery for resistance or intolerance/noncompliance is likely to decrease substantially with these new agents. Increasing efficacy and greater ease of administration of somatostatin analogues for GH, and for rare TSH, adenomas are also anticipated to lead to less reliance on surgery and radiation therapy as the primary therapy in these disorders. Although somewhat unclear at this time, GH antagonists hold promise for alternative or adjunct therapy for acromegaly. Given the significant morbidity and mortality associated with acromegaly, these advances are quite encouraging. Unfortunately, little if any progress has been made toward establishing an effective medical treatment for gonadotropin or nonsecreting tumors. However, new approaches to delivery of radiation therapy may reduce some of the inconvenience and risk of this treatment for patients when surgery alone is inadequate. In all of these disorders, the challenge to physicians and their patients remains one of choosing a rational combination of medical, surgical, and radiation therapy. Fortunately, for most patients, control, if not cure, of their pituitary adenoma is a reasonable expectation.

Correlation of antipsychotic and prolactin concentrations in children and adolescents acutely treated with haloperidol, clozapine, or olanzapine

Patients with a Diagnostic and Statistical Manual of Mental Disorders (third edition, revised) diagnosis of schizophrenia or psychotic disorder not otherwise specified with onset of psychosis before the age of 13 participated in 6- to 8-week open or double-blind trials of haloperidol (n = 15, mean dose 15.4 +/- 8.1 mg/day [0.27 +/- 0.15 mg/kg/day]), clozapine (n = 30, mean dose 269.9 +/- 173.3 mg/day [4.4 +/- 2.6 mg/kg/day]), or olanzapine (n = 12, mean dose 17.5 +/- 2.8 mg/day [0.30 +/- 0.13 mg/kg/day]). Blood samples were obtained at 6 weeks for evaluation of haloperidol, reduced haloperidol, clozapine, desmethylclozapine, and olanzapine plasma concentrations and serum prolactin concentrations. No gender differences were noted for antipsychotic dose or concentration within each treatment group. Correlations between antipsychotic plasma concentration and serum prolactin concentration were significant only for the olanzapine treatment group (r = 0.80, p = 0.002). Separate correlations for gender were significant only for females receiving olanzapine (r = 0.91, p = 0.03); the patient with the highest serum prolactin experienced galactorrhea. Further studies evaluating the prolactin-elevating properties of antipsychotics are warranted in this population.

Plasma prolactin and central D2 receptor occupancy in antipsychotic drug-treated patients

Previous studies of the relationship between plasma prolactin and clinical effects in patients treated with antipsychotic drugs have yielded inconsistent results. A possible explanation may be that most studies have not included subtherapeutic or low doses of antipsychotics. In this exploratory, double-blind study, the relationship between plasma prolactin concentration and central D2 receptor occupancy was examined in 13 schizophrenic patients treated with the experimental antipsychotic drug raclopride (2, 6, or 12 mg daily). D2 receptor occupancy was determined by positron emission tomography and was related to antipsychotic effect as measured by the Brief Psychiatric Rating Scale. Plasma prolactin concentration was increased in eight of nine patients with a D2 receptor occupancy greater than 50%, whereas it was normal among patients with a D2 receptor occupancy less than 50% (p < 0.01). Plasma prolactin concentration measured 4 hours after the morning dose of raclopride correlated significantly with plasma raclopride concentration (r = 0.92, p < 0.01), the degree of D2 receptor occupancy (r = 0.81,p < 0.01), and the antipsychotic effect (r = 0.79, p < 0.01). Further controlled studies that include low doses of antipsychotic drugs may warrant a reconciliation of plasma prolactin as a useful tool in clinical monitoring of antipsychotic drug treatment.

Effects of acute and long-term domperidone treatment on prolactin and gonadal hormone levels and sexual behavior of male and female rats

Domperidone (DOMP), a dopamine D2 blocker that is unable to cross the blood-brain barrier, is an experimental tool used to induce hyperprolactinemia. Acute and long-term DOMP administration was tested in male and female rats for its effects on sexual behavior and plasma gonadal hormone levels. DOMP (4.0 mg/kg) was injected I.P. either acutely or daily for 30 days. Acute treatment failed to modify any behavioral parameter observed. The 5-day treatment stimulated and the 30-day treatment failed to inhibit sexual behavior of male rats. Serum testosterone levels were significantly reduced after 30 days of treatment in male rats. The 30-day treatment also inhibited sexual behavior and enhanced plasma progesterone levels in ovariectomized and intact female rats, respectively. The present results may be due to DOMP-induced long-term hyperprolactinemia. Alternatively, blockade of dopamine peripheral receptors induced by this treatment may also be responsible for the behavioral changes reported here. Moreover, these data suggest that female rats are more susceptible than males to the behavioral effects of long-term hyperprolactinemia.

Plasma concentrations of remoxipride and haloperidol in relation to prolactin and short-term therapeutic outcome in schizophrenic patients

Plasma concentrations of remoxipride and haloperidol as well as prolactin (PRL) were determined in 20 patients with acute symptoms of schizophrenia. Ten patients received remoxipride and ten patients haloperidol for a period of 6 weeks. A significant linear correlation was found between the plasma level of remoxipride and the dosage applied (P less than 0.02) as well as between the corresponding haloperidol dosage and plasma concentration (P less than 0.05). In both patient groups a significant reduction in psychopathology was observed during the trial period (P less than 0.001). In the haloperidol group this was associated with a clearcut elevation of plasma PRL, whereas in the remoxipride group after an initial rise for 4 weeks, the mean PRL level returned to baseline at the end of the study.

Relationship of psychotic symptoms to haloperidol-stimulated prolactin release

Prolactin (PRL) response to a single dose of intravenous haloperidol (0.5 mg) was measured as a marker of tuberoinfundibular dopamine (TIDA) activity in 24 neuroleptic-free, male, psychotic patients. The PRL responses were then correlated with psychotic symptoms measured with Andreasen's Scales for the Assessment of Positive and Negative Symptoms (SAPS, SANS). Correlation analyses revealed a significant inverse relationship between PRL response and the severity of delusional symptoms. There was no significant correlation between the symptoms of hallucinations, formal thought disorder, or global negative symptoms and PRL response to haloperidol, nor were there any significant correlations between basal PRL and symptom severity. These results suggest that among the positive and negative symptoms associated with psychoses, only delusions may be associated with TIDA overactivity.

Basal and haloperidol-stimulated prolactin in neuroleptic-free men with schizophrenia defined by 11 diagnostic systems

Forty-four male, neuroleptic-free, acutely psychotic patients with at least one diagnosis of schizophrenia among 11 diagnostic systems, and 28 healthy controls, underwent measurement of prolactin (PRL) concentrations before and after intravenous administration of haloperidol (0.5 mg). Basal PRL concentrations were lower in the patients with Research Diagnostic Criteria (RDC) DSM-III, Cloninger, and Taylor and Abrams schizophrenias than in controls. Compared with the controls, the PRL response to haloperidol was lower in the patients with schizophrenia defined by all diagnostic systems except those of Schneider and M. Bleuler. Neither basal nor stimulated PRL concentrations were correlated with positive symptoms, but basal PRL was correlated with the Brief Psychiatric Rating Scale (BPRS) depression-related subscore. This study lends further support for the presence of dopaminergic dysfunction in schizophrenia, and demonstrates the advantages and problems in the use of multidiagnostic psychopathological evaluation to categorize a disorder where there is major disagreement among diagnostic systems.

Self-reported neuroendocrine effects of antipsychotics in women: a pilot study

Although neuroendocrine adverse effects (NAEs) of antipsychotic agents in women have been widely reported, it has been generally assumed that either (1) tolerance to these effects develops with chronic use, (2) patients adjust to the effects, or (3) a trial of dopamine-agonist treatment is effective. We have begun to examine the prevalence of chronic adverse effects and their effect on compliance using a pilot study of self-reported NAEs, antipsychotic drugs, and compliance patterns in a naturalistic setting. Twenty chronic psychiatric outpatients who had been continuously prescribed antipsychotic agents for a minimum of six months were interviewed. The major finding is the greater antipsychotic dose exposure among those with self-reported NAEs compared with those without NAEs (781 +/- 606 chlorpromazine-equivalent mg/d vs. 125 +/- 117, p less than 0.001). High-potency agents were prescribed for all of the patients reporting amenorrhea and/or galactorrhea, although the relationship between potency group (high vs. low) and total neuroendocrine effects was not significant. Self-reported compliance was not significantly related to neuroendocrine adverse effects. However, a trend toward the association of self-reported galactorrhea and noncompliance (p = 0.08) is noted. The implications of these findings and a suggested approach for their replication in a more powerful statistical analysis is discussed.

Selective dopamine D2 antagonist and prolactin response in acute schizophrenia--results from remoxipride studies. The Canadian Remoxipride Study Group

1. In a double-blind dose finding study prolactin was assessed at baseline and end of treatment in three groups of acute schizophrenics receiving low, intermediate and high doses of remoxipride as compared to a controlled group that received haloperidol. 2. Remoxipride only in high doses (300-600 mg daily) has produced a modest increase in prolactin levels at endpoint as compared to the much higher increase in prolactin secretion that accompanied haloperidol treatment. 3. The weak effects on prolactin as well as the previously reported low incidence of extrapyramidal side effects confirm the profile of remoxipride as a selective dopamine D2 antagonist with preferential effects on the mesolimbic and mesocortical tracts. 4. Male responders to either remoxipride or haloperidol treatment had significantly higher baseline prolactin levels regardless of dose and drug used. In females, there was no difference in baseline prolactin between responders and nonresponders.

Pharmacokinetics of haloperidol and fluphenazine decanoates in chronic schizophrenia

In a double-blind comparison of haloperidol decanoate and fluphenazine decanoate given 4-weekly for 60 weeks as maintenance therapy in 38 chronic schizophrenic in-patients, plasma haloperidol, fluphenazine and prolactin levels were measured at regular intervals by radioimmunoassay. After the first injection, the mean plasma haloperidol level was highest at week 1 and fell gradually towards week 4. Mean pre-dose haloperidol levels changed little after week 8. Results suggested an absorption half-life of 4 weeks, although, in three cases steady state was only achieved after 11 monthly injections. Steady state levels of both haloperidol and fluphenazine correlated highly with dose. In two sub-groups observed at steady state, both drugs produced a biphasic pattern of plasma drug concentration between injections, a rapid rise on day 1 followed by stable elevated levels and a gradual return to pre-injection concentration by the end of week 4. In the fluphenazine sub-group there was a second peak on day 7 and a steeper decline, so that the mean area-under-curve in week 4 was 64% of that in week 1. Drug injections at steady state induced an increase in prolactin secretion in all of the fluphenazine sub-group and in half of those receiving haloperidol. Plasma prolactin changes resembled those for drug concentrations, but differences in times of peaks on day 1 resulted in weak correlations. Fluphenazine appeared more potent than haloperidol in provoking prolactin secretion.

Seasonal variations in prolactin levels in schizophrenia

As part of an ongoing longitudinal study of drug-free schizophrenic patients, we serially sampled resting early morning prolactin levels in 10 subjects. In a preliminary analysis, these levels were compared to those found in matched normal control subjects over a 4-year period. Both control and schizophrenic subjects showed a marked annual variation in prolactin levels. Six schizophrenic patients sampled in each quarter of the year showed a significant annual rhythm, with prolactin highest in the spring (March-May). In seven schizophrenic patients and nine controls sampled at two seasons in the year, prolactin was significantly higher in spring-summer (March-August) than in fall-winter (September-February), with no difference between patients and control subjects.

Effects of 4 weeks treatment with chlorpromazine and/or trihexyphenidyl on the pituitary-gonadal axis in male paranoid schizophrenics

Serum prolactin (PRL), luteinizing hormone (LH) and testosterone (T) levels were estimated in a group of 30 male paranoid schizophrenics before and after 4 weeks treatment with chlorpromazine and/or trihexyphenidyl, and in a group of 14 healthy male individuals. After treatment with chlorpromazine (100 mg t.i.d., p.o.), 10 patients presented a significant increase in serum PRL values and a significant decrease in serum T values. A significant increase in serum PRL values was also found in 10 patients who were treated with chlorpromazine (100 mg t.i.d., p.o.) plus trihexyphenidyl (5 mg t.i.d., p.o.). No significant difference in any of the investigated endocrine parameters was detected in 10 patients after 4 weeks administration of trihexyphenidyl (5 mg t.i.d., p.o.). Following chlorpromazine treatment with or without concomitant administration of trihexyphenidyl, 20 patients showed a significant increase in serum PRL levels and a significant decrease in serum LH and T levels.

The patterns of prolactin release by ECT and TRH compared

The patterns of prolactin release after bilateral ECT and after 0.4 mg TRH i.v. were studied in 11 female melancholic patients in a 5-min sampling protocol. Mean prolactin peaking times were 10.2 min after ECT and 20.5 min after TRH. The elimination rate coefficients were significantly lower--and the corresponding half-lives longer--for prolactin released by TRH than by ECT. A significant positive correlation of the maximal prolactin responses by the two stimuli was also found.

Prophylactic effects of neuroleptics in symptom-free schizophrenics: roles of dopaminergic and noradrenergic blockers

A clinical trial was undertaken to determine the role of dopaminergic and noradrenergic blockers in the maintenance treatment of remitted schizophrenics. One hundred and six remitted schizophrenic outpatients were treated with one of nine treatments, viz., thioridazine 25 mg or 75 mg, pimozide 2 mg or 6 mg, and their respective combinations, for 1 year in a double-blind controlled study employing a randomized design. The data from a previous study were utilized as a retrospective placebo group. Pimozide prolonged the number of symptom-free days in a dose-dependent manner and did so more markedly than thioridazine. Combined administration of pimozide and thioridazine prolonged the number of symptom-free days to a greater extent than their single administration. However, an inverted U-shaped dose-response curve was obtained with the combined administration of these agents. These data suggest that both the dopaminergic and noradrenergic blocking action of neuroleptics are important in preventing relapse in remitted schizophrenics.

Prolonged inhibition of striatal dopamine receptor sites by isofloxythepin

Using the [3H]spiperone binding technique to measure the residual drug effect of subcutaneously injected isofloxythepin (1 mg/kg, single dose) in the rat, we observed a significant blockade of [3H]spiperone-labeled, high affinity dopamine receptors (D2) in the striatum up to 4 days after drug administration. Higher doses of isofloxythepin (5 or 10 mg/kg) produced a receptor blockade and were associated with an inhibition of apomorphine-induced stereotypy which lasted more than a week. Neither dopaminergic behavior supersensitivity nor striatal D2 receptor up-regulation was observed in isofloxythepin-treated rats, even after the animals were withdrawn from the drug for an extended period of time. Isofloxythepin was shown to decrease the Bmax without altering the KD of [3H]spiperone binding (a non-competitive inhibition), and in vitro its binding was not readily dissociated even when the drug-receptor complex was washed repeatedly with large volumes of drug-free buffer. The IC50 of isofloxythepin for displacing [3H]spiperone binding was 0.8 nM. Isofloxythepin is therefore a potent dopamine receptor antagonist with prolonged pharmacological action and strong binding at D2 receptors.

Specific in vivo binding of 3H-spiperone to individual lobes of the pituitary gland of the rat. Evidence for the labelling of dopamine receptors

The in vivo binding of 3H-spiperone to individual lobes of the pituitary gland was studied after intravenous injections in unanesthetized male rats. The binding was found to be saturable and reversible. The percentage of total binding of 3H-spiperone that was specific binding was highest in the intermediate (approximately equal to 75%) and lowest in the posterior (approximately equal to 35%) lobes. The regional distribution of 3H-spiperone binding 1 hour after injections was the following: intermediate greater than anterior greater than posterior. Pharmacological analysis of the in vivo 3H-spiperone binding showed that dopamine agonists (e.g. bromocriptine, N-n-propylnorapomorphine) and antagonists could prevent the in vivo binding of 3H-spiperone in all three parts of the gland. The substituted benzamide drugs remoxipride and raclopride blocked the in vivo 3H-spiperone binding in the anterior and intermediate lobes but did not reduce the 3H-spiperone binding in the posterior part, except when given in very high doses. Taken together, the present study has shown that 3H-spiperone can be used in studies of the dopamine receptors in the anterior, intermediate and posterior lobes of the pituitary gland, but the proportion of non-specific binding is higher than in the striatum. The use of in vivo 3H-spiperone binding may thus be a useful method to study the regulation and pharmacology of these receptors in situ.

Autoradiographic study of 14C-sulpiride in monkey

Substituted benzamides have been the object of numerous metabolic studies including many by whole body autoradiography of rats and mice. The present study reports autoradiographic data concerning 14C-labelled Sulpiride in monkey. The Study was limited to the brain in order to elucidate the controversial question as to whether the drug can cross the blood-brain barrier. The results showed that in monkey, as in rat and mouse, there is no localization in the brain as can be clearly seen on the autoradiograms. In view of these results and of the undeniable neuroleptic properties of Sulpiride, an indirect mode of action through the release of endogenous mediators is proposed.

The relationship of dopamine receptor blockade to clinical response in schizophrenic patients treated with pimozide or haloperidol

Pimozide and haloperidol were found to be equally effective in the treatment of acute schizophrenia in a double-blind clinical trial involving 22 patients. Drug plasma levels measured by radioimmunoassay (RIA) did not correlate with clinical response following either drug. Nor was there any correlation between clinical response and the dopamine receptor blocking activity of either drug as measured by radio receptor assay (RRA). Following pimozide plasma prolactin (PRL) levels correlated with clinical change, although the time courses of response of PRL and clinical response were dissimilar. There was no correlation between PRL and clinical response to haloperidol. RRA and RIA values correlated highly following pimozide but not haloperidol. Our findings lead us to conclude that the RRA technique reflects the plasma level of a drug rather than its central dopamine blocking activity. We also consider that the clinical response to antipsychotic drugs in schizophrenia may be less directly linked to dopamine receptor blockade than has previously been supposed.

Prolactin response to single and multiple doses of haloperidol in schizophrenic patients

Serum prolactin and blood levels of haloperidol were assessed in schizophrenic patients after single acute oral doses of haloperidol and during fixed dose treatment with this medication. Although significant intrapatient correlations between prolactin responses to different doses of haloperidol were found, no statistically significant interpatient relationship between haloperidol dose and prolactin response emerged. There were statistically significant relationships between steady-state plasma and red cell haloperidol levels (measured by radioreceptor or gas liquid chromatographic techniques) and serum prolactin response, but not between blood levels after the acute haloperidol dose and prolactin response.

The relationship between prolactin levels and clinical ratings in manic patients treated with oral and intravenous test doses of haloperidol

Twelve manic patients were treated for 2 weeks with oral haloperidol; in 6 patients treatment commenced with intravenous haloperidol, and intravenous 'test' doses were given after 1, 3-5 and 14 days of oral medication. From 24 hours to 14 days baseline serum prolactin levels rose towards a plateau, as did the improvement in clinical ratings. After the first intravenous test doses of haloperidol, prolactin levels peaked at 1 hour; however, they fell to a low point at 24 hours, and no response to further test doses was seen for 3-5 days. The response tended to return at 14 days. The mechanisms underlying the changes in prolactin levels, and in clinical state, are discussed.

Prolactin and cortisol in cerebrospinal fluid: sex-related associations with clinical and psychological characteristics of patients with low back pain

Clinical and psychological characteristics of 33 patients with low back pain were correlated with prolactin and cortisol concentrations in cerebrospinal fluid (CSF). A significant sex difference was found in CSF prolactin levels: women secreted more prolactin into the CSF than did men. High CSF cortisol levels were associated with a rhizographically-demonstrable abnormality, suggesting a relationship between cortisol and an 'organic' origin of pain symptoms. Impairment-disability indices also were associated with CSF hormone levels. Moreover, the two hormones had dissociated psychological correlates. Prolactin was related to depression and anxiety, whereas cortisol was related to somatization. Sex differences were observed in the cortisol response to the symptoms of chronic low back pain, especially in the presence of anxiety and somatization. The sex differences in psychoneuroendocrine and emotional responses suggest that male and female pain patients have different coping mechanisms.

Plasma prolactin and growth hormone levels in manic patients treated with pimozide

During two weeks' treatment of 11 manic patients with pimozide there was close correspondence between the timecourse of improvement in clinical ratings and the rise in plasma prolactin between the second and fourteenth day. There were no significant differences in growth hormone levels during the manic episodes compared to recovery. These findings are discussed in relation to the role of dopamine in the release of prolactin and growth hormone, and in the pathogenesis of mania.

Neuroendocrine tests during treatment with neuroleptic drugs I. Plasma prolactin response to haloperidol challenge

The plasma prolactin (PRL) response to haloperidol 2 or 4 mg i.m. was studied in 18 schizophrenic men during their routine treatment with neuroleptic drugs. A substantial rise of the PRL level above the treatment baseline occurred in all but four of the 20 tests showing that the PRL elevation induced by treatment was not maximal. The challenge was ineffective only in patients receiving very high daily doses of medication. The increment was inversely correlated to the daily dose of medication but unrelated to plasma haloperidol concentrations during the test. Chronic schizophrenics who were receiving long term treatment and had low basal PRL levels did not show tolerance to the prolactin stimulating effect of haloperidol. That prolactin rose during the test in patients who had improved during their current treatment indicates that the degree of dopamine receptor blockade required for therapeutic effects is below that which produces a maximal PRL response.

Anterior pituitary hormone levels in the cerebrospinal fluid of patients with pituitary and parasellar tumors

Cerebrospinal fluid (CSF) concentrations of growth hormone, prolactin (PRL), adrenocorticotropin, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, and the glycoprotein hormone alpha subunit were determined in 30 patients with pituitary and parasellar tumors. Although many of the patients had elevated hormone levels, no differentiation between patients with intrasellar tumors and those with pituitary tumors with suprasellar extension or primary suprasellar tumors could be made based upon the absolute CSF hormone concentration. A highly significant correlation between serum and CSF PRL concentrations was found (r = 0.87; P less than 0.001), suggesting that CSF PRL is derived from the serum. No correlation was found between the serum and CSF concentrations of the other anterior pituitary hormones.

Effect of intramuscular chlorpromazine on serum prolactin levels in schizophrenic patients and normal controls

Serum prolactin levels were monitored for 2 hours after injection of chlorpromazine (CPZ) 50 mg intramuscularly (i.m.) in 6 male normal controls and 14 newly admitted male chronic schizophrenics. The increase in serum prolactin levels in the male normal controls was not significantly different from that in patients. Serum prolactin levels were compared in 18 male and 22 female psychotic patients of various psychiatric diagnoses who received 50 mg of CPZ i.m., and 7 male and 6 female patients who received 25 mg CPZ i.m. No significant sex or dose differences were seen in the magnitude of the prolactin response after i.m. CPZ. These results suggest that doses of CPZ 25 or 50 mg i.m. may result in maximal prolactin secretion in most subjects and that lower doses are needed to test the hypothesis that dopamine receptors are supersensitive in schizophrenia or the affective psychoses. In six patients with mixed diagnoses, serum levels of CPZ and other active metabolites were determined by radioreceptor binding assay; peak serum drug levels were highly correlated with peak serum prolactin levels (4 = 0.92) during the first 2 hours following CPZ 50 mg i.m.