Comparison of sertraline and nortriptyline in the treatment of major depressive disorder in late life

OBJECTIVE

This study was designed to evaluate the comparative efficacy and safety of sertraline and nortriptyline for the treatment of major depressive disorder in older adults.

METHOD

A double-blind, parallel group design was used to compare 210 outpatients, 60 years of age and older, who met DSM-III-R criteria for major depressive episode and had a minimum Hamilton Depression Rating Scale score of 18. The patients were randomly assigned to 12 weeks of treatment with either sertraline (50-150 mg/day) or nortriptyline (25-100 mg/day).

RESULTS

The safety profiles of the two treatments were similar except that nortriptyline treatment was associated with a significant increase in pulse rate, whereas sertraline was associated with a nonsignificant decrease. Efficacy of both drugs was similar for both treatments at all time points, with 71.6% (N=53 of 74) of the sertraline-treated patients and 61.4% (N=43 of 70) of the nortriptyline-treated patients achieving responder status by week 12. Time to response was also similar, with more than 75% of the improvement in scores on the Hamilton depression scale having occurred by week 6. Secondary efficacy measures (posttreatment measures of cognitive function, memory, and quality of life) revealed a significant advantage for sertraline treatment.

CONCLUSIONS

Primary efficacy measures showed sertraline and nortriptyline to be similarly effective. With secondary outcome measures there was consistent evidence of an advantage for the sertraline-treated group. The clinical impact of these measures on the long-term well-being of elderly depressed patients should be examined in a study of maintenance treatment.

Cognitive factors and stress-induced changes in catecholamine biochemistry

The purpose of the present research was to determine whether dysfunctional attitudes, a cognitive attribute, predicted changes in catecholamine biochemistry. A cognitive task was used to induce stress in female subjects (n=21), and levels of plasma norepinephrine (NE) and homovanillic acid (HVA) were measured at three time points: at baseline (T1); immediately after stress exposure (T2); and 40 min later (T3). Dysfunctional attitudes were significantly and positively related to levels of plasma NE at T3, controlling for baseline levels. Dysfunctional attitudes were not significantly related to plasma HVA levels at any time point. Our findings provide initial support for the idea that dysfunctional attitudes, an attribute shown to play an important role in some forms of unipolar depression, predict stress-induced alterations in noradrenergic output.

The effect of novel antipsychotics in rat oral dyskinesia

1. The effect of the D1 agonist SKF38393 and the 5HT2C agonist m-CPP on repetitive jaw movements (RJM) was studied in rats. Acute administration of SKF38393 and/or m-CPP induced RJM in a dose dependent manner. In rats treated with both drugs, RJM responses were about equal to the sum of those obtained with each drug alone. 2. The induction of RJM by SKF38393 was somewhat lower in rats pretreated with 5HT2C receptor antagonist, mianserin, whereas mianserin severely reduced RJM induced by m-CPP alone. 3. D1 antagonist SCH23390 inhibited SKF38393 induced RJM but had no effect on m-CPP induced chewing behavior. 4. The present study confirms earlier evidence that D1 agonists used at optimal doses for the induction of RJM do not involve the serotonergic system in a significant way. It does, however, implicate the system in the emergence of drug induced oral behavior in rats. 5. The effect of the atypical antipsychotics, clozapine, olanzapine and risperidone was studied on SKF38393 and m-CPP induced RJM. Pretreatment with the atypical antipsychotics clozapine and olanzapine inhibit SKF38393 and m-CPP induced RJM. Pretreatment with risperidone inhibits m-CPP induced oral behavior in rats while increases dose dependently SKF38393 induced RJM.

Effects of repeated amphetamine treatment on regional GABAA receptor binding

The present study examined the effects of repeated exposure to amphetamine on GABAA receptor binding in cortical and subcortical areas. The goal of the study was to determine whether changes in specific binding were related to behavioral sensitization. Animals were exposed to either saline (0.3 ml, s.c.; n=12) or d-amphetamine (2.5 mg/kg, s.c.; n=12) for 6 consecutive days and sacrificed after a 14-day withdrawal period. Differences in GABAA receptor binding in these two groups of animals were assessed using the GABAA receptor antagonist [3H]SR 95531. To verify that the preceding treatment regimen led to the development of behavioral sensitization, a separate set of animals (n=8/group) was exposed to the same regimen and challenged with d-amphetamine (2.5 mg/kg, s.c.) after the 14-day withdrawal period. As expected, preexposure to amphetamine led to the development of amphetamine sensitization. There were no differences in GABAA receptor binding in animals preexposed to saline and amphetamine in the prefrontal cortex, caudate-putamen, hypothalamus, or cerebellum. These findings do not provide support for the idea that changes in GABAA receptor binding in the medial prefrontal cortex or various subcortical areas are related to the development of behavioral sensitization.

A phosphoinositide-linked dopamine D1 receptor mediates repetitive jaw movements in rats

BACKGROUND

We have demonstrated that rats injected with D1 agonists SKF 38393 or A68930 demonstrate repetitive jaw movements (RJM). These agonist-induced movements in rats are similar in their appearance to those induced in rats by long-term treatment with antipsychotic drugs. Over recent years D-1 receptors were discovered which showed linkage not only to c-AMP but also to PI hydrolysis. We examined the effect of EEDQ inactivation of D1 receptors on D-1 mediated PI hydrolysis and RJM.

METHODS

Twenty four hours following EEDQ or vehicle administration D-1 agonists or vehicle were administered. The number of RJM episodes was assessed in EEDQ and vehicle treated rats. D-1 receptor density and inositol phosphate formation were determined in the striata.

RESULTS

EEDQ administration resulted, 24 hours later, in 70-80% selective depletion of D-1 receptors in the striata but did not modify the rate of RJM induced by D-1 agonists. There was no significant difference in D-1 mediated PI hydrolysis in EEDQ treated rats when compared to vehicle treated group.

CONCLUSIONS

The present data support the earlier demonstration of D-1 agonist induced RJM, an effect mediated by a subpopulation of a D-1 receptor subtype and constitute the first behavioral evidence for the existence of a behavioral response mediated by D-1 like dopamine receptors linked to an alternate second messenger system-PI hydrolysis.

Differential regulation of D2 receptor gene expression by transcription factor AP-1 in cultured cells

The role of the transcription factor AP-1 in regulating D2 receptor transcriptional activity was investigated in D2 receptor expressing neuroblastoma cells, NB41A3, and in non-D2 receptor expressing CHO cells. Deletion of a region containing the putative AP-1 binding site resulted in a significant reduction in the activity in CHO cells; while the activity in NB41A3 cells was increased suggesting that the AP-1 site may differentially regulate D2 gene expression in these distinct cell types. However, both cell lines were found to express significant and similar levels of the transcription factors AP-1. Analysis of phosphorylated proteins in each of the cell lines provided evidence that AP-1 is phosphorylated in NB41A3 cells, but not in CHO cells. This result suggests that differential regulation of D2 gene expression may be related to AP-1 phosphorylation.

Vulnerability to stress: self-criticism and stress-induced changes in biochemistry

It has been hypothesized that individuals who are high on the attribute of self-criticism are particularly vulnerable to failure stress. To test this hypothesis, we examined the relationship between self-criticism and changes in plasma homovanillic acid (HVA; the metabolite of dopamine) and emotion during exposure to an induced-failure task. Participants consisted of 21 women. Plasma HVA and emotion were assessed at three time points: baseline (T1), during stress exposure (T2), and 40 minutes after cessation of the stressor (T3). We found that self-criticism was significantly and positively related to changes in plasma HVA during stress exposure. In addition, the personality attribute was significantly and positively related to subjective ratings of stress and changes in scores on the Confusion-Bewilderment scale of the Profile of Mood States during the task. To our knowledge, this is the first study to report that self-criticism is related to stress-induced changes in biochemistry.

Novelty-associated locomotion: correlation with cortical and sub-cortical GABAA receptor binding

The present study was designed to determine whether variability in GABA (eta-aminobutyric acid)A receptor binding in cortical and subcortical brain regions was correlated with locomotor activity in a novel environment. Twenty four animals were rated for locomotor activity in a novel circular runway. Eight days later, locomotor activity was assessed following 1.5 mg/kg amphetamine sulfate (i.p.). After four to six days, animals were killed and samples were pooled in groups of four animals ranked according to novely locomotor score, and specific binding of the GABAA receptor antagonist [2-(3'-carboxy-2'-propyl)-3-amino-6-p-methoxy phenylpyridazinium bromide] ([3H]SR95531) was determined. Significant negative correlations were seen between specific ([3H]SR95531) binding and novelty induced locomotion in the cingulate and prefrontal cortices, and in the ventral pallidum. A near-significant negative correlation was seen in the striatum. Correlation coefficients between locomotion scores in the novel environment and specific [3H]SR95531 binding were: cingulate cortex, R = -0.91, P = 0.012; prefrontal cortex, R = -0.85, P = 0.032; ventral pallidum, R = -0.85, P = 0.030; striatum, R = -0.73, P = 0.097; and nucleus accumbens, R = -0.09, P = 0.85. The positive correlation between novelty- and amphetamine-induced locomotion was also quite high (R = 0.95, P = 0.004). These results are discussed in terms of their relevance to potential biochemical correlates of drug abuse vulnerability.

Causes of haloperidol discontinuation in patients with Tourette's disorder: management and alternatives

BACKGROUND

Neuroleptics are considered the mainstay of treatment in Tourette's disorder, and haloperidol is deemed the treatment of choice by many. Factors such as treatment efficacy and the side effects that appear in response to neuroleptic administration have been implicated in affecting medication compliance. However, a detailed evaluation of these factors has yet to be undertaken in Tourette's disorder.

METHOD

Of 51 consecutive referrals to a Tourette's disorder clinic, 48 met DSM-III-R criteria for Tourette's disorder. Of these 48, 28 had previously received neuroleptics. In this set of 28 patients, 24 (16 male, 8 female) had initially received treatment with haloperidol, and they made up the present sample; their ages ranged from 10.4 to 47.9 years (mean = 27.1), and age at onset ranged from 2 to 16 years. Each patient completed an evaluation consisting of a Tourette Syndrome Questionnaire and a clinical interview with the patient and involoved family members. Charts were also reviewed to gather information concerning side effects and other factors that led to haloperidol discontinuation and/or noncompliance.

RESULTS

Duration of treatment ranged from 3 days to 14 years (mean = 3.6 years). In this sample, 12.5% (3/24) of the subjects continued medication without interruption (mean +/- SD = 8.4 +/- 5.1 years of medication). Of the 21 patients who discontinued haloperidol, 66.7% (14/21) did so because they experienced intolerable side effects, 9.5% (2/21) because of the fear of experiencing certain side effects, and 14.3% (3/21) because of a combination of these factors. The principal side effects that led to discontinuation included dysphoric reactions, akathisia, nervousness, sedation, dystonic reactions, and cognitive dulling/feeling drugged.

CONCLUSION

Careful monitoring of side effects and efficacy is essential to continued compliance with haloperidol. In addition, psychoeducation about potential consequences of medication administration may help promote compliance in those patients who develop fears of possible adverse reactions.

Repeated inescapable stress produces a neuroleptic-like effect on the conditioned avoidance response

This study tests the hypothesis that the dopaminergic system mediates a restitutive response by decreasing its own activity in the face of events like persistent inescapable stress that threaten to interrupt organized mental activity. It is well established that neuroleptic drugs inhibit the conditioned avoidance response (CAR), but not the escape response, probably via a reduction in subcortical dopaminergic activity. We trained rats to perform the CAR and then subjected them to acute and chronic stress to determine whether this would result in inhibition of the CAR. Rats subjected to twice daily tailshock stress for 8 days showed inhibition of the CAR and a reduction in dopamine (DA) utilization in the nucleus accumbens. These findings are compatible with the hypothesis that an endogenous DA-dependent mechanism exists that mimics neuroleptic effects in the face of repeated stress. In humans this response may serve as a protection against psychotic decompensation from chronic endogenous or exogenous insult.

Alterations in GABAA receptor binding in the prefrontal cortex following exposure to chronic stress

The present study was designed to examine the effects of chronic stress on GABAA receptor binding. Animals were randomly assigned to either a control, acute, or chronic stress condition and changes in specific binding were assessed using the GABAA receptor antagonist [3H]SR 95531. Exposure to chronic restraint stress led to a significant reduction in GABAA receptor binding in the prefrontal cortex. Alterations in specific binding were not observed in the cerebellum, caudate-putamen, hippocampus, or cingulate cortex however, suggesting that the effects of chronic stress may be regionally specific. Exposure to acute restraint did not lead to a significant alteration in [3H]SR 95531 binding in any brain region examined.

Schizophrenia: gender, family risk, and plasma homovanillic acid

Plasma homovanillic acid concentration was assessed in 60 young schizophrenic patients, with and without first-degree relatives with schizophrenia, before treatment, and 3 days after starting haloperidol treatment. The baseline concentration of homovanillic acid in plasma was no different in the two groups before treatment; it was, however, significantly higher in the patients with relatives than in those without relatives diagnosed of schizophrenia after 3 days of haloperidol treatment.

Environmental factors and related fluctuation of symptoms in children and adolescents with Tourette's disorder

The purpose of this paper is to assess how 29 different environmental factors affected Tourette symptomatology in 14 children and adolescents (6.6-14.5 years; mean 10.3) who had never received any medication for their disorder. Assessment was based on patients' responses to the Tourette Syndrome (TS) Questionnaire. Eleven different factors were associated with a decrease in symptoms and included doctor visits, talking to friends, and reading for pleasure. The 10 factors reported to have no impact on Tourette symptomatology included various foods, weather, and living away from home. Seventeen factors associated with an increase in Tourette symptoms included events causing anxiety, emotional trauma, and social gatherings.

Possible genetic factors underlying the pathophysiology of tardive dyskinesia

Rates of spontaneous and drug-induced repetitive jaw movements (RJM) in rats vary widely. Low and high RJM responders were isolated and genetically selected. At each generation mean RJM responses (spontaneous or SKF 38393-induced) of the two types of rats were found to differ significantly, whereas neither apomorphine-induced stereotypic responses nor D1 and D2 receptor numbers and affinities differed. A significant increase in cAMP production was evident in SKF 38393-stimulated striatal homogenates of high RJM responders as compared with low responders. Animals subjected to 8-months exposure to fluphenazine exhibited RJM that were about twice as great as that of controls, 2 months after the last treatment, with a prevalence of about 75%. Similarities between RJM observed in rats and neuroleptic-induced tardive dyskinesia suggest that the two are strongly related.

Persistent Tardive Dyskinesia and Other Neuroleptic-Related Dyskinesias in Tourette's Disorder

ABSTRACT Two new cases are reported of persistent tardive dyskinesia associated with neuroleptic treatment of patients with Tourette's disorder. Previously, 44 cases were described in 8 published reports, including 36 children and adolescents, but diagnostic criteria were infrequently specified. In our review of these cases, using the criteria of Schooler and Kane but modified by Gualtieri's more conservative duration criteria of 16 weeks, only 2 of these cases were consistent with a diagnosis of persistent tardive dyskinesia. The 2 new cases are reported here. A 12-year-old, who was treated with haloperidol 4 mg daily since the age of 8, developed fine vermicular movements of the tongue of moderate severity. Despite discontinuation of the neuroleptic, symptoms of tardive dyskinesia still persisted at age 15 and were associated with difficulty in speech production. A 42-year-old, who was treated with haloperidol 1 mg three times daily for 7 years, developed jaw movements and lip smacking that persisted for more than 2 years. Abnormal involuntary movement scale (AIMS) ratings supported a diagnosis of tardive dyskinesia in both patients with Tourette's disorder. The identification of tardive dyskinesia in the setting of a preexisting movement disorder is discussed. Features that helped distinguish the movements of tardive dyskinesia and Tourette's disorder in these patients included the premonitory urges of Tourette's symptoms and a differential response of the symptoms to distracting voluntary motor tasks. Clinicians should be attentive and thorough in searching for symptoms of tardive dyskinesia following treatment with relatively low doses of haloperidol in patients with Tourette's disorder.

A subpopulation of dopamine D1 receptors mediate repetitive jaw movements in rats

Repetitive jaw movements (RJM) in rats, a potentially useful animal model of tardive dyskinesia, appears to be mediated by the dopamine D1 receptor as evidenced in part by their induction and inhibition with D1 agonists and D1 antagonists, respectively. Selective destruction of 60-90% of D1 receptors by EEDQ, measured in several CNS dopaminergically innervated areas, preceded by protection of D2, 5-HT2, alpha 1 and alpha 2 receptors, however, failed to reduce D1 agonist-augmentable RJM. Further, the affinity of dopamine toward displacement of 3H-SCH-23390 binding from striatal D1 receptors was significantly decreased by administered EEDQ, a counter-intuitive result in relation to D1 responsitivity and RJM. Thus, at present it is suggested that an EEDQ-resistant D1 receptor subpopulation may exist.

A mechanism underlying neuroleptic induced oral dyskinesias in rats

Previously we have found that spontaneous repetitive jaw movements (RJM) in rats can be augmented by dopamine D1 receptor stimulation and attenuated by D2 stimulation or by D1 blockade. We now report that high and low RJM responders can be inbred and that RJM responses in such rats are further augmented during washout from eight months of treatment with fluphenazine, a time when N-propyl-apomorphine induced stereotypy is severely depressed. Moreover, selective D1 receptor inactivation by N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) fails to reduce RJM. Therefore, D2 blockade by neuroleptics is deemed to be the most important mechanism for RJM enhancement. In conclusion, our studies show that oral behaviors are under genetic control, perhaps suggesting that the appearance of tardive dyskinesia in only some patients under neuroleptic therapy is due to a genetic disposition. Furthermore, tardive dyskinesia may be less likely to develop if the neuroleptics used are less potent against D2 receptors, as has been reported for some of the atypical antipsychotic drugs.

Site-directed mutagenesis of tyrosine hydroxylase. Role of serine 40 in catalysis

We have investigated the role of serine 40 (Ser-40) in tyrosine hydroxylase (TH) catalysis of basal and activated enzymes by protein kinase A (PKA)-mediated phosphorylation. Wild type and mutant TH were transiently and stably expressed in AtT-20 cells, and the enzymatic activities of the recombinant enzymes were analyzed. The specific enzymatic activity of transiently expressed TH mutants Ser-40-->leucine or-->tyrosine (Leu-40m or Tyr-40m) was higher than that of the wild type enzyme or of other mutants in which Ser-8, -19, and -31 were replaced by leucine. The kinetic studies carried out with the stably expressed TH show that the Km for the cofactor 6-methyltetrahydropterine is lower and the Ki for dopamine is higher when the enzymatic hydroxylation is catalyzed by the Leu-40m or Tyr-40m than by the wild type enzyme. The kinetic parameters and the pH profile of the enzymatic hydroxylation catalyzed by the Leu-40m or Tyr-40m are similar to the enzyme activated by PKA-mediated phosphorylation. We suggest that Ser-40 in TH exerts an inhibitory influence on the enzymatic activity, and its replacement with another amino acid by site-directed mutagenesis or its modification by phosphorylation leads to a change in conformation with an increased enzymatic activity. The importance of Ser-40 in the activation of TH by PKA-mediated phosphorylation was investigated by comparing the activation of the wild type enzyme with that of Leu-40m or Tyr-40m. The findings that the enzymatic activity is increased by PKA-mediated phosphorylation of the wild type enzyme, but not of the Leu-40m or Tyr-40m, demonstrate that phosphorylation at Ser-40 is essential for activation of TH by PKA. The findings that addition of ATP plus cAMP to homogenates from transfected AtT-20 cells stimulates the recombinant wild type TH activity indicate that these cells contain endogenous cAMP-dependent protein kinase.

Tonic inhibition of striatal dopamine transmission: effects of benzodiazepine and GABAA receptor antagonists on extracellular dopamine levels

At present, it is unclear whether ligands which bind at the benzodiazepine/GABA receptor complex play a tonic modulatory role with regard to striatal dopamine (DA) transmission. The present study was designed to examine the effects of Ro15-1788, a benzodiazepine (BZ) receptor antagonist, and SR 95531, a GABAA receptor antagonist, on striatal extracellular DA (DA[e]) concentrations in anesthetized and awake rats using the technique of in vivo microdialysis. Local administration of Ro15-1788 resulted in a dose-dependent increase in DA[e] in both anesthetized and awake animals. The Ro15-1788-induced increase in DA[e] was blocked by coadministration of the BZ agonist diazepam, as well as GABA. Local administration of SR 95531 also resulted in a dose-dependent alteration in striatal DA levels in both anesthetized and awake animals. The SR 95531-induced increase in DA was blocked by coadministration of GABA. The results suggest that GABA may play a tonic inhibitory role with regard to striatal DA transmission.

Receptor reserve for D2 dopaminergic inhibition of prolactin release in vivo and in vitro

The full dopamine agonist R-(-)-N-n-propylnorapomorphine (NPA) completely suppressed (ED50 0.12 micrograms/kg) serum prolactin (PRL) levels elevated by pretreatment with gamma-butyrolactone (750 mg/kg). Pretreatment with the receptor-inactivating agent N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (1 and 2 x 6 mg/kg) progressively shifted the dose-response curve for NPA to the right, but PRL secretion was still maximally inhibited. Receptor inactivation elicited smaller (2-fold) dextral shifts in the ED50 for the partial agonists (+)- and (-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine. These results are consistent with the presence of a sizable receptor reserve at the D2 receptor regulating PRL release in the anterior pituitary. Analogous results were obtained in vitro utilizing primary cultures of anterior pituitary cells. NPA potently inhibited basal PRL release in culture (ED50 0.06 nM, maximal inhibition 83%). Receptor alkylation with phenoxybenzamine (1 microM, 1 hr) did not affect basal PRL release but right-shifted the ED50 for NPA more than 6-fold and attenuated maximal inhibition (to 68%); both effects were significant (P less than .01). The extracellular accumulation of cyclic AMP (cAMP) stimulated by a combination of forskolin (1 microM) and 3-isobutyl-1-methyl xanthine (100 microM) required higher concentrations of NPA (ED50 0.36 nM), and the maximal effect was much smaller (46%). Phenoxybenzamine treatment did not alter either basal or forskolin-stimulated cAMP accumulation, but it reduced the maximal inhibitory response to NPA (to 13%) without shifting the ED50. Plots of receptor occupancy vs. response demonstrated a 60% receptor reserve for NPA inhibition of PRL release, but none for inhibition of cAMP production.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence of low dopaminergic activity in elderly women with spontaneous orofacial dyskinesia

Evidence of low dopaminergic activity was found in elderly women exhibiting spontaneous orofacial dyskinesias. The dyskinesia was significantly reduced by haloperidol. The results are not compatible with dopamine receptor supersensitivity in this dyskinesia.

Interleukin-1 stimulates the beta-amyloid precursor protein promoter

1. Amyloid plaques found in the brains of Alzheimer's diseased patients are composed of the 42 amino acid beta-amyloid peptide (BAP) which is processed out of the larger amyloid precursor protein (APP). 2. To study the regulation of the APP gene expression, we have isolated the promoter region of this angle of this single-copy gene and produced a reporter gene system to determine if the promoter is responsive to agents that may cause the overproduction of APP leading to the abnormal accumulation of plaques in AD. 3. The promoter contains sequences homologous to heat shock elements, AP-1 binding sites, and phorbol ester-inducible sequences as well as GG-rich regions found in other constitutively expressed genes. 4. We show here that this promoter is inducible in cultured cells by interleukin-1 (IL-1) in a transient assay system and that the HSE and AP-1 binding site are required for this inducibility. 5. This induction of transcription from the APP promoter implies that this gene is responsive to tropic and/or trophic agents which may be present in the diseased brain.

Antihypertensive therapy and quality of life: a comparison of atenolol, captopril, enalapril and propranolol

This randomized, double-blind parallel study compared the effects of atenolol, captopril, enalapril and propranolol in 360 men with mild-to-moderate essential hypertension. Patients were titrated until diastolic blood pressure (Korotkoff phase V) decreased by at least 10 mmHg or to 90 mmHg or less. Quality of life assessments, based on validated psychometric questionnaires and objective measurements of cognitive function, occurred after three study phases: placebo run-in (3-5 weeks), titration (1-4 weeks), and maintenance (4 weeks). After four weeks of maintenance therapy, atenolol, captopril and enalapril generally had equivalent effects on quality of life, as measured by psychometric questionnaires, whereas propranolol consistently evidenced worsening or less improvement. Global scores of distressing psychological symptoms differed as a function of specific treatment (P = 0.01), with improvements significantly better for the atenolol, captopril and enalapril groups as compared with the propranolol group. There were no statistically significant differences among treatments for changes in cognitive function at maintenance. Thus, the quality of life questionnaires differentiated among drugs of the same class, indicating that selection among antihypertensive drugs should be based on their specific qualities, not on general class characteristics.

The effect of hyperthyroidism on opiate receptor binding and pain sensitivity

This study was conducted to determine the effect of thyroid hormone on opiate receptor ligand-binding and pain sensitivity. Specific opiate receptor-binding was performed on brain homogenates of Swiss-Webster mice. There was a significant increase in 3H-naloxone-binding in thyroxine-fed subjects (hyperthyroid). Scatchard analysis revealed that the number of opiate receptors was increased in hyperthyroid mice (Bmax = 0.238 nM for hyperthyroid samples vs. 0.174 nM for controls). Binding affinity was unaffected (Kd = 1.54 nM for hyperthyroid and 1.58 nM for control samples). When mice were subjected to hotplate stimulation, the hyperthyroid mice were noted to be more sensitive as judged by pain aversion response latencies which were half that of control animals. After morphine administration, the hyperthyroid animals demonstrated a shorter duration of analgesia. These findings demonstrate that thyroxine increases opiate receptor number and native pain sensitivity but decreases the duration of analgesia from morphine.

A full repetitive jaw movement response after 70% depletion of caudate D1 receptors

Repetitive jaw movements (RJM in the rat can be produced in a dose-dependent manner with the selective D1 agonist, SKF 38393. Administration of the protein coupling agent, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) to rats pretreated with a D2 receptor blocker resulted in a 70-30% reduction of D1 dopamine receptors, but only a 10% reduction of D2 receptors in the rat caudate. Twenty-four hours following EEDQ, the RJM response to SKF 38393 was assessed. The massive selective reduction of the D1 receptor density was found not to modify the rate of RJM induced by SKF 38393 in that dose response curves in control and EEDQ-treated rats were essentially identical. These data provide evidence to indicate that there is a functional D1 receptor reserve for D1-mediated RJM behavior.

Persistence of cyclicity of the plasma dopamine metabolite, homovanillic acid, in neuroleptic treated schizophrenic patients

The dopamine metabolite, homovanillic acid, decreases in concentration in plasma between 8:30 A.M. and 12:30 P.M. In patients with schizophrenia this cyclic change is attenuated by chronic neuroleptic treatment; however, if the 8 A.M. dose of neuroleptic is omitted, the decrease in level occurs. Presuming that neuroleptics attenuate the decline through a receptor mediated compensatory increase in dopamine release, it would appear that receptors are not fully occupied by neuroleptics even at therapeutically effective doses. The usual morning decrease in plasma cortisol levels was unaffected by neuroleptics.

Effects of prenatal exposure to neuroleptic drugs on children's growth

The effect of prenatal exposure to neuroleptic drugs on height and weight from birth to 7 years was examined in children of psychiatrically normal parents and of parents with a history of psychiatric treatment, using data from the Collaborative Perinatal Project of the National Institute of Neurological Diseases, Communicative Disorders, and Stroke. Analysis of covariance was used to control for potential confounding factors. We found that prenatal exposure to dopamine receptor-blocking neuroleptic drugs was associated with increased height in one or more of our groups at 4 months, 1 year, and 7 years and less consistently with increased weight. Seven-year-old children who had been exposed to these drugs for more than 2 months during gestation were approximately 3 cm taller than unexposed controls (p less than 0.05). Prenatal exposure to dopamine-depleting agents was associated with decreased height at 4 months but not later. Possible mechanisms for these effects, including a permanent decrease in the number of brain dopamine receptors and effects on various hormones, are discussed.

Plasma homovanillic acid as a predictor of response to neuroleptics

Fourteen schizophrenic subjects were evaluated for degree of psychosis before and after treatment with the antipsychotic drug haloperidol and for plasma homovanillic acid concentration after four and 28 days of treatment. A significant correlation was found between an increase in homovanillic acid concentration on day 4 or a decrease from day 4 to day 28 and the degree of improvement after four weeks of treatment. Thus, those patients who had the greatest change in plasma homovanillic acid in response to neuroleptic blockade showed the greatest improvement. These and other observations have led us to propose that the central dopaminergic system, through adaptive changes in activity, serves as a physiologic buffer system protecting against destabilization of mental function from diverse biologic or psychologic insults.

Diminished D2 dopamine receptor function and the emergence of repetitive jaw movements

Oral movements in rats, repetitive jaw movements (RJM), can be induced in a dose dependent manner by a specific D1 agonist, SKF 38393, and decreased by D2 receptor stimulation with a specific D2 agonist, LY 141865. Irreversible D1 receptor inactivation by N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline severely reduced oral responses induced by SKF 38393, whereas such blockade of D2 receptors greatly augmented the D1 mediated behavior. Further, we found that chronic prolonged D2 receptor blockade following administration of fluphenazine decanoate facilitated repetitive jaw movements.

Relationship between receptor occupancy and response at striatal dopamine autoreceptors

The irreversible dopamine (DA) receptor antagonist N-ethoxy-carbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) was used to determine the extent of receptor reserve at DA autoreceptors regulating in vivo tyrosine hydroxylase activity. Rats were treated with vehicle or EEDQ (1 X 0.5-2 X 6 mg/kg, subcutaneously) and, 24 hr later, dose response curves were generated for DA agonist reversal of gamma-butyrolactone-induced striatal L-3,4-dihydroxyphenylalanine (L-DOPA) accumulation. Double reciprocal plots were obtained of equieffective doses of agonist required to elicit response at several levels of effect before and after partial irreversible receptor inactivation. A pseudo-dissociation constant (pseudo-KA, in units of dose) and the fraction of receptors remaining active (q) were determined; these values were then used to calculate the relationship between receptor occupancy and response. The ED50 (1 microgram/kg) for the full DA receptor agonist N-propylnorapomorphine (NPA) was shifted 2.8, 4.8-, and 11.3-fold to the right after partial irreversible receptor blockade which left the fraction of receptors remaining active (q) at 0.37, 0.17 and 0.058, respectively. Corresponding maximal reversal of L-DOPA accumulation was 100, 77, and 58%, indicating a nonlinear relationship between receptor occupancy and response for NPA and the presence of a large receptor reserve; maximal and half-maximal responses were calculated to require occupancy of 30 and 3.8% of the total receptor pool, respectively. Dose response curves were also obtained for the DA autoreceptor-selective agents EMD 23,448 and (+)- and (-)-3-PPP before and after EEDQ treatment. In controls, EMD 23,448 and (+)-3-PPP, like NPA, completely reversed striatal gamma-butyrolactone-induced L-DOPA accumulation, whereas the maximal effect of (-)-3-PPP was 52% reversal. After EEDQ treatment (6 mg/kg), EMD 23,448 and (+)-3-PPP showed relatively small shifts in ED50 values. Furchgott analysis demonstrated that all three atypical agents are partial agonists at the DA autoreceptor with efficacies of 0.19 (EMD 23,448), 0.12 [(+)-3-PPP], and 0.05 [(-)-3-PPP] relative to NPA. The presence of a larger receptor reserve at pre-versus postsynaptic D2 DA receptors and the partial agonist character of drugs such as EMD 23,448 and the enantiomers of 3-PPP may account for their autoreceptor selectivity.

Clinical and treatment effects on 3H-clonidine and 3H-imipramine binding in elderly depressed patients

3H-clonidine and 3H-imipramine binding were measured in depressed patients, 55 years and older. There was no significant difference in either 3H-clonidine or 3H-imipramine binding between depressed patients and age- and sex-matched controls. There was no significant correlation between 3H-clonidine or 3H-imipramine binding and severity of depression before treatment. There was a significant negative correlation between the KD of 3H-imipramine binding sites and Hamilton score over seven weeks of antidepressant treatment. There was no significant difference between receptor data of responders and nonresponders to antidepressant treatment.

Selective dopamine D2 receptor reduction enhances a D1-mediated oral dyskinesia in rats

We have previously shown, through the use of selective D1 and D2 dopamine receptor interactive drugs, that repetitive jaw movements in rats can be produced by activation of the D1 system or blockade of the D2 system. In the present study we have shown that genetic or developmental factors resulting in a lesser number of D2--relative to D1--receptors is associated with repetitive jaw movements. We have found in two strains of rats with different striatal D2 to D1 ratios, the strain with fewer D2 sites had more jaw movements. We also found that experimental reduction of D2 receptors via prenatal intervention resulted in an increase in spontaneous jaw movements, as did aging, which is accompanied by a decrease in the number of D2 receptors. The findings of these studies carried out in rats, parallel, in a number of ways, findings in human oral dyskinesia associated with either aging or neuroleptic treatment.

Receptor reserve at striatal dopamine autoreceptors: implications for selectivity of dopamine agonists

The dose response curve for apomorphine reversal of gamma-butyrolactone (GBL)-induced L-DOPA accumulation in rat striatum was shifted almost 6-fold to the right after partial irreversible blockade (83%) of dopamine (DA) autoreceptors with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ); however, the maximal response was not reduced. In contrast, the major effect of a similar degree of irreversible blockade (86%) on the dose-response curve for the autoreceptor-selective agent EMD 23,448 was a reduction in maximal response (60% of control), indicating that EMD 23,448 is a partial agonist. A large receptor reserve therefore exists at the DA autoreceptor, which may explain in part why many DA agonists are more potent in models pre- than postsynaptic receptor activation.

Prenatal neuroleptic exposure alters postnatal striatal cholinergic activity in the rat

Previous studies in our laboratory have shown that prenatal exposure to a neuroleptic during a critical period of gestation in the rat results in a marked deficit in the number of striatal dopamine-binding sites and in a diminution of dopamine agonist-induced stereotyped behavior. In the present studies, we examined the effect of prenatal neuroleptic exposure on biochemical parameters of cholinergic activity to determine whether the balance between striatal dopaminergic and cholinergic activity might be altered. The number of muscarinic cholinergic-binding sites and the specific activity of choline acetyltransferase were found to be significantly increased by prenatal treatment with the neuroleptics haloperidol or (+)-butaclamol. From the present studies and previous observations made in our laboratory, it is concluded that the ability of a neuroleptic to affect the number of muscarinic cholinergic receptors in postnatal life may be a result of the phenotypically undifferentiated state of the developing dopamine-binding site. Our findings of increased striatal cholinergic activity accompanied by a marked decrease in dopaminergic activity may have implications for an increased vulnerability to extrapyramidal motor disturbances during postnatal development.