sincalide and Schizophrenia

It has been suggested that cholecystokinin (CCK), a gut-brain peptide found in high concentrations in the mammalian brain, might be implicated in the neurobiology of anxiety and panic disorder. The administration of CCK tetrapeptide induced panic attacks analogous to spontaneous ones in patients suffering from panic disorder and to a lesser degree in healthy volunteers. In animal models of anxiety, the pretreatment with CCK agonists and antagonists produced, respectively, anxiogenic- and anxiolytic-like action on the exploratory paradigms. On the other hand, CCK could also play a role in the pathophysiology of schizophrenia. The administration of CCK agonists (caerulein, CCK-8s) to rodents results in behavioural effects analogous to those of antipsychotic drugs. However, CCK agonists lack any activity in rodent behavioural models to reveal antipsychotic drugs. A significant reduction of CCK concentration and CCK receptors has been shown in cortical and limbic structures of patients suffering from schizophrenia. Nevertheless, administration of CCK agonists to these patients does not effect their symptoms. Two major conclusions should be drawn: first, CCK is involved in the neurobiology of anxiety; second, changes in the CCK system in schizophrenia could be linked to a cortical neurodegeneration related to this disease.

Topics: Animals; Anxiety Disorders; Ceruletide; Cholecystokinin; Humans; Neurotransmitter Agents; Receptors, Cholecystokinin; Schizophrenia; Sincalide

Topics: Animals; Antipsychotic Agents; Brain; Diagnostic Imaging; Dopamine; Dopamine Antagonists; Glucose; Humans; Neurons; Receptors, Dopamine; Schizophrenia; Sincalide

Topics: Animals; Cholecystokinin; Dopamine; Electrophysiology; Humans; Mesencephalon; Models, Biological; Nucleus Accumbens; Rats; Schizophrenia; Sincalide; Synapses

Topics: Animals; Behavior, Animal; Cholecystokinin; Clinical Trials as Topic; Dopamine; Humans; Limbic System; Mesencephalon; Schizophrenia; Sincalide

CCK-IR is co-localized with DA in some DA neurons projecting to limbic structures. The extent of the co-localization is species dependent. The co-localization of CCK and DA is of interest in view of the DA hypothesis of schizophrenia and the putative role of limbic dysfunction in the pathophysiology of this disorder. In animals biochemical, electrophysiological and behavioural studies point to an interaction between CCK and DA. Whereas some investigations point to an inhibitory effect on DA function, which would be compatible with a potential antischizophrenic action, others point to an enhancement or no effect. CCK peptides show a neuroleptic-like profile in several screening tests for neuroleptics but not in all studies. In man there is endocrinological evidence for an inhibitory effect of CCK-33 and CCK-8 on DA function. However, alternate explanations are possible. CSF CCK-IR is unchanged or decreased in schizophrenia. Autopsy investigations have shown significant decreases, increases or no change in brain CCK-IR concentrations and a decrease in CCK-33 binding in schizophrenia. Eight of 11 clinical trials with CER, CCK-8 or CCK-33 have shown a therapeutic effect in schizophrenia; only two of these eight trials have been double-blind studies. The three controlled investigations which have shown no effect have used only small patient populations. None of the trials have used an active placebo. It is difficult to reconcile the apparent long duration of antipsychotic activity with the short half-life of the peptides and problems of the peptides in crossing the blood brain barrier. Despite these apparent anomalies information to date is sufficiently impressive to warrant further detailed investigation of CCK-DA-interactions and the evaluation of the clinical effects of a variety of CCK peptides and related compounds, natural and synthetic, which may more easily cross the blood brain barrier and which may show regional selectivity in site of action in brain.

Topics: Antipsychotic Agents; Ceruletide; Cholecystokinin; Dopamine; Humans; Neurotransmitter Agents; Receptors, Dopamine; Schizophrenia; Sincalide

Topics: Animals; Behavior, Animal; Cholecystokinin; Clinical Trials as Topic; Dopamine; Humans; Limbic System; Mesencephalon; Schizophrenia; Sincalide

A group of 14 schizophrenics who remained symptomatic after neuroleptic treatment received either 0.02 mcg/kg CCK-8 or saline placebo intravenously. Thereafter, 13 received the alternative infusion as a crossover treatment. A second group of 16 such patients received 0.04 mcg/kg CCK-8 or saline intravenously and, thereafter, 14 of these received the alternative infusion as a crossover treatment. Psychopathology was rated prior to, 2-3 h post, and on days 3, 5 and 7 after each infusion. Ratings consisted of the BPRS, the Abrams and Taylor Scale for Emotional Blunting, the Hamilton Anxiety Scale and a Schneiderian "Positive" symptom scale abstracted from the President State Examination. Parallel groups and cross over design analyses failed to show efficacy for CCK-8.

Topics: Antipsychotic Agents; Clinical Trials as Topic; Double-Blind Method; Gastrointestinal Diseases; Humans; Placebos; Schizophrenia; Sincalide

Topics: Animals; Ceruletide; Cholecystokinin; Clinical Trials as Topic; Feeding Behavior; Humans; Motor Activity; Parkinson Disease; Receptors, Dopamine; Schizophrenia; Sincalide; Synapses

Antipsychotic properties of cholecystokinin have been suggested both in laboratory studies and in some open clinical trials, mainly in patients suffering from chronic schizophrenia. Eighteen patients (14 males, 4 females) meeting Research Diagnostic Criteria for schizophrenia had been receiving neuroleptics at a dosage that had not changed for 3 months, and to which the patients were at best only partially responsive. The patients were randomized into groups that received weekly intravenous injections of 10 micrograms of CCK-8 or normal saline over 8 weeks. Neuroleptic medication was unchanged for the study. Baseline and weekly assessments were carried out using the Brief Psychiatric Rating Scale (BPRS) and the Schizophrenia Subscale of the Present State Examination (SS-PSE). Analysis of covariance revealed significant differences between CCK-8 and placebo over the study period on the Thought Disturbance Factor and Total Score of the BPRS, and on the Nuclear Syndrome, Total Delusion Factor, and Total Score of the SS-PSE. No important side effects were noted. It is concluded that CCK-8 has definite antipsychotic properties in patients with chronic schizophrenia. Clinical trials in neuroleptic-free patients are warranted.

Topics: Animals; Brief Psychiatric Rating Scale; Chronic Disease; Clinical Trials as Topic; Double-Blind Method; Female; Humans; Male; Schizophrenia; Sincalide

Eight neuroleptic-resistant schizophrenic patients were treated with ceruletide diethylamine, a cholecystokininlike peptide, in a placebo-controlled, double-blind, cross-over study. Ceruletide or placebo was administered intramuscularly twice a day for four consecutive days while patients received a constant dose of fluphenazine hydrochloride. Cholecystokinin octapeptide was also administered to four different schizophrenic patients in a double-blind, cross-over study. Cholecystokinin or placebo was administered as a slow intravenous infusion daily for four days. There were no changes in either the positive or negative symptoms of schizophrenia between the periods of placebo, ceruletide, or cholecystokinin administration. Furthermore, there was no tendency for the patients' conditions to either improve or worsen during the course of ceruletide or cholecystokinin treatment. In contrast to previous reports from uncontrolled studies, cholecystokininlike peptides appear to be devoid of antipsychotic properties when administered parenterally.

Topics: Adult; Ceruletide; Chronic Disease; Clinical Trials as Topic; Double-Blind Method; Female; Humans; Male; Placebos; Psychiatric Status Rating Scales; Schizophrenia; Schizophrenic Psychology; Sincalide

Topics: Adult; Antipsychotic Agents; Female; Humans; Male; Middle Aged; Neurosecretory Systems; Psychiatric Status Rating Scales; Receptors, Dopamine; Schizophrenia; Sincalide

Local microiontophoretic administration of cholecystokinin octapeptide (CCK) increased the firing rates of neurons in the dorsomedial nucleus accumbens (NAc), but exerted little to no effect on lateral NAc neurons. This regionally defined CCK-effect corresponds to the topographical distribution of CCK-like immunoreactive nerve terminal fiber networks and CCK receptors within the NAc. The excitatory effects of CCK were selectively antagonized by the CCK antagonist proglumide. Dopamine (DA) decreased the firing of NAc cells and reversed CCK-induced excitation. These results suggest that CCK and DA may interact to influence the activity of neurons within the dorsomedial NAc.

Topics: Animals; Antipsychotic Agents; Dopamine; Drug Interactions; Glutamates; Glutamic Acid; Humans; Male; Nucleus Accumbens; Proglumide; Rats; Rats, Inbred Strains; Receptors, Cell Surface; Receptors, Cholecystokinin; Schizophrenia; Septal Nuclei; Sincalide