Effects of penfluridol and other drugs on apomorphine-induced stereotyped behavior in monkeys

Molecular rhythm alterations in prefrontal cortex and nucleus accumbens associated with opioid use disorder

Severe and persistent disruptions to sleep and circadian rhythms are common in people with opioid use disorder (OUD). Preclinical evidence suggests altered molecular rhythms in the brain modulate opioid reward and relapse. However, whether molecular rhythms are disrupted in the brains of people with OUD remained an open question, critical to understanding the role of circadian rhythms in opioid addiction. Using subjects' times of death as a marker of time of day, we investigated transcriptional rhythms in the brains of subjects with OUD compared to unaffected comparison subjects. We discovered rhythmic transcripts in both the dorsolateral prefrontal cortex (DLPFC) and nucleus accumbens (NAc), key brain areas involved in OUD, that were largely distinct between OUD and unaffected subjects. Fewer rhythmic transcripts were identified in DLPFC of subjects with OUD compared to unaffected subjects, whereas in the NAc, nearly double the number of rhythmic transcripts was identified in subjects with OUD. In NAc of subjects with OUD, rhythmic transcripts peaked either in the evening or near sunrise, and were associated with an opioid, dopamine, and GABAergic neurotransmission. Associations with altered neurotransmission in NAc were further supported by co-expression network analysis which identified OUD-specific modules enriched for transcripts involved in dopamine, GABA, and glutamatergic synaptic functions. Additionally, rhythmic transcripts in DLPFC and NAc of subjects with OUD were enriched for genomic loci associated with sleep-related GWAS traits, including sleep duration and insomnia. Collectively, our findings connect transcriptional rhythm changes in opioidergic, dopaminergic, GABAergic signaling in the human brain to sleep-related traits in opioid addiction.

Penfluridol as a Candidate of Drug Repurposing for Anticancer Agent

Penfluridol has robust antipsychotic efficacy and is a first-generation diphenylbutylpiperidine. Its effects last for several days after a single oral dose and it can be administered once a week to provide better compliance and symptom control. Recently; strong antitumour effects for penfluridol were discovered in various cancer cell lines; such as breast; pancreatic; glioblastoma; and lung cancer cells via several distinct mechanisms. Therefore; penfluridol has drawn much attention as a potentially novel anti-tumour agent. In addition; the anti-cancer effects of penfluridol have been demonstrated in vivo: results showed slight changes in the volume and weight of organs at doses tested in animals. This paper outlines the potential for penfluridol to be developed as a next-generation anticancer drug.

Differential effects of dopaminergic agonists on food-reinforced operant behavior in the long-tailed macaque (Macaca fascicularis)

Dopaminergic involvement in the regulation of operant behavior was examined by monitoring responding after administration of different dopaminergic agonists. A chain schedule of reinforcement was used to classify the effects of these agonists in long-tailed macaques (Macaca fascicularis). The schedule included the following: (1) a 30-s time-out period; (2) a clock-cued 30-s period of differential reinforcement of zero-response rate; (3) a time-in period whose duration depended on response latency; (4) a 2-s reinforcement period in which applesauce was delivered. This cycling schedule maintained a low operant rate and was sensitive to both inhibition (decreases) and excitation (increases) of responding. IV injection of the dopaminergic agonists resulted in the following two basic effects: (1) d-amphetamine and amfonelic acid disrupted performance by response inhibition, which was shown not to be attributable to anorexia; (2) apomorphine and bromocriptine disrupted performance by response excitation. Both effects were reduced by pretreatment with trifluperidol, a dopaminergic antagonist. The results, indicating that dopaminergic systems mediate disruption of food-reinforced operant behavior by altering the frequency of responding, are interpreted in terms of the known neuropharmacological actions of the agonists.

Antiapomorphine and locomotor effects of neuroleptics in rhesus monkeys

Intramuscular injections of apomorphine (1 mg/kg) cause marked behavioral effects in rhesus monkeys including hyperactivity, repetitive stereotyped movements, chewing, tongue movements, licking, biting and vocalization. These effects occur within minutes of the injection and last 90-100 min. The antiapomorphine and locomotor depressant activity of chlorpromazine, haloperidol, MD 790501, sultopride and thioridazine, injected IM 1 hr before apomorphine, were assessed using a standardized rating procedure. All compounds antagonized the effects of apomorphine but differed in terms of potency and their relative effects on locomotor activity. The experimental compound MD 790501, a new benzamide derivative, was not only the most potent compound tested but, compared with its antagonism of apomorphine, caused the least marked depression of locomotor activity.

Dose-dependent behavioural changes induced by apomorphine in selected members of a primate social colony

The effect of six acute doses of the dopamine receptor agonist apomorphine on non-human primate social and individual behaviour was studied in a social colony of four adult Stumptail macaques. Apomorphine was administered intramuscularly to 2 monkeys/day in doses ranging from 0.05 to 3.00 mg kg-1 15 min bfefore a 1 h observation period. Apomorphine induced hyperactivity, hypervigilance, and stereotyped behaviour at doses of 0.50 mg kg-1 and greater in all 4 monkeys. In addition it also caused a dose-dependent disruption of normal behavioural patterns. Social grooming was eliminated while the submissive gestures were significantly increased. It also induced an increase in vocalizations and suppression of food forage behaviours. The results demonstrate the role of dopamine systems in the mediation of affiliative behaviour as well as motor behaviour in a primate species. Also, since similar behavioural changes are induced in this species during chronic (+)-amphetamine treatment, it is suggested that dopamine systems play a predominant role in amphetamine-induced behaviour in primates.

Interaction of apomorphine and haloperidol: effects on locomotion and other behaviour in the marmoset

The behavioural effects of increasing doses of apomorphine and haloperidol were observed in a group of six marmosets. Behaviour was classified quantitatively into categories: Locomotion, inactivity, checking (small head movements), social interaction and purposeful activities. Statistical analysis revealed that apomorphine had a stimulant effect on checking and locomotion which could be antagonized by haloperidol. Activities and social contact were severly reduced by both apomorphine and haloperidol. Inactivity was increased by the lowest dose of apomorphine in otherwise untreated animals. It is suggested that haloperidol antagonizes the stimulant effects of apomorphine but is synergistic to its suppressant effects, and that the low dose effect of apomorphine on inactivity is mediated by a mechanism which may be different from that acted upon by haloperidol.

Effects of neuroleptics on morphine-induced tail erection in mice

Morphine elicits dose-dependent tail erection in mice. Pretreatment of mice with atropine, phenoxybenzamine, propranolol, diphenhydramine, cyproheptadine or parachlorophenylalanine did not interfere with tail erection induced by morphone. Several neuroleptic drugs which are dopamine receptor blocking agents showed a clear antagonistic effect on morphine-induced tail erection (MITE). Haloperidol and penfluridol blocked MITE at doses which only produced a slight behavioral depression. Pimozide and chlorpromazine were less antagonistic than haloperidol and penfluridol and inhibited MITE only at doses which produced a marked behavioral depression. Results indicated that dopamine might be involved in tail erection induced by morphine. MITE in mice might be a useful model for the evaluation of neuroleptic drugs.

Susceptibility to amphetamine-elicited dyskinesias following chronic methadone treatment in monkeys

Eight rhesus monkeys that had drunk subdependence-producing doses of methadone daily for 10-22 months, and had subsequently been drug-free for 2-17 months, were injected with low doses of methamphetamine (MA). They immediately exhibited oral dyskinesias resembling the symptoms of tardive dyskinesia in humans, a condition resulting from chronic blockade of striatal dopamine receptors by neuroleptics. Eleven control monkeys failed to develop dyskinesias during prolonged MA administration. Control monkeys then received parenteral methadone, chlorpromazine, haloperidol, or saline for 45 days. Upon subsequent retest with MA, the methadone and chlorpromazine monkeys immediately displayed oral dyskinesias. Dopaminergic antagonists blocked MA-elicited dyskinesis, whereas neither a noradrenergic blocker nor sedative doses of phenobarbital and diazepam had any effect on dyskinesias. We suggest that receptor supersensitivity is produced by chronic treatment with methadone or other dopamine receptor blockers. Following treatment, stimulation of hypersensitive striatal receptors by the dopamine released by MA results in oral dyskinesias. The clinical implications for methadone maintenance treatment program patients are discussed.

Dyskinesias in monkeys: interaction of methamphetamine with prior methadone treatment

Rhesus monkeys with a history of drinking methadone, but presently drug-free, were injected with low doses of methamphetamine (MA). They immediately developed oral dyskinesias resembling the symptoms of tardive dyskinesia in humans, a condition resulting from chronic blockade of striatal dopamine receptors by neuroleptics. Nine of 11 control monkeys failed to develop dyskinesias during prolonged MA administration. A stressful stimulus intensified the MA-elicited oral dyskinesias, an effect analogous to exacerbation of tardive dyskinesias by emotional stress. Control monkeys were then injected with methadone, chlorpromazine, haloperidol, or saline for 45 days. Ten days following this chronic treatment, MA immediately elicted oral dyskinesias in the methadone and chlorpromazine monkeys. Acute administration of the dopaminergic blocking agents chlorpromazine, spiroperidol, and clozapine eliminated MA-elicited dyskinesias, whereas the alpha-adrenergic blocker phentolamine was ineffective. Physostigmine blocked the dyskinesias in 1 of 2 cases. Sedative doses of phenobarbital and diazepam had no effect on oral dyskinesias. These data indicate that chronic treatment with methadone or other dopamine receptor blocking agents leads to receptor supersensitivity to the actions of MA.