Depression by morphine of the resting and evoked release of [3H]-acetylcholine from the cat caudate nucleus in vivo

Long-Term Substance Use Can Cause Irreversible Photopic Vision Changes in Substance Use Disorder in Remission

OBJECTIVE

Substance use has such effects on pupil diameter. Although there is knowledge about the acute effects of substances on pupils, studies showing their chronic effects are limited. The aim of the present study was to evaluate the effect of long-term substance use on scotopic, mesopic, and photopic vision.

METHODS

The present study with cross-sectional desgn was conducted at the Adiyaman Training and Research Hospital for Psychiatry in Adiyaman. This study involved 110 substance use disorder (SUD) patients and 46 healthy volunteers as the control. The parameters were measured and recorded automatically by a device.

RESULTS

The mean age was 23.44±5.53 years in the SUD group and 24.26±5.38 years in healthy controls (p=0.420). The mean age of onset of the substance was 17.74±3.89 years and the mean duration of substance use was 3.54±2.9 years. It was determined that the patients had not used any substance for a mean of 121.73±117.49 days. There was no significant difference between patient and control groups in terms of scotopic and mesopic measurements of both eyes (p>0.05). Photopic measurements were significantly higher in the patient group than in the control group (p<0.05). Photopic measurements were significantly higher in the opioid, cannabis, ecstasy, and multiple substance use groups than in the control group (p<0.05).

CONCLUSION

The most important topic of this study is that photopic vision is permanently impaired in patients with a history of chronic substance use. This was attributed to disrupted sympathetic-parasympathetic hierarchy.

Treatment of opioid-induced delirium with acetylcholinesterase inhibitors: a case report

A 55-year-old woman with advanced ovarian cancer and severe pain developed hypoactive delirium after an increase in her opioid dosage. Myoclonus and delirium improved dramatically with the intravenous injection of the acetylcholinesterase inhibitor physostigmine, and this improvement was maintained during the administration of donepezil, an oral medication with similar pharmacodynamic properties. Evidence for a disorder of cholinergic neurotransmission in opioid-induced delirium is discussed, as is the rationale for treatment with acetylcholinesterase inhibitors and other cholinomimetic agents.

Donepezil in the treatment of opioid-induced sedation: report of six cases

Donepezil, an oral acetylcholinesterase inhibitor approved for the treatment of Alzheimer's disease, was given to 6 cancer pain patients having sedation related to the analgesic use of opioids. Each patient was taking more than 200 mg of oral morphine equivalents per day, and several were receiving complex analgesic regimens consisting of multiple adjuvant medications. Sedation improved at least moderately in 5 of the patients and mildly in 1 after they began taking donepezil. Patients reported a decrease in episodes of spontaneous sleeping during the day, fewer myoclonic twitches, improved daily function and greater social interaction. Several also reported improved sleep at night. Analgesia was not compromised by the use of donepezil, and in some cases it appeared improved. Donepezil may be a valuable alternative to psychostimulants in the treatment of opioid-induced sedation. A prospective controlled trial comparing the treatment effects of psychostimulants and donepezil on patients having opioid-induced sedation is underway.

Effect of morphine and morphine-like drugs on carbachol-induced fighting in cats

In the present experiments, morphine, methadone or pethidine was injected into the cerebral ventricle of the unanesthetized cat after fighting was induced with carbachol injected previously. The fighting evoked by carbachol was sensitive to the depressant action of morphine or pethidine but not to the depressant effect of methadone. The most likely explanation of the depressant effects of the former compounds is that they act on the postsynaptic receptors of central cholinergic neurons.

Altered caudate nucleus field potentials following sustained stimulation to different substantia nigra regions

Evoked potential recording techniques were used as a physiological tool for electrode placement into the substantia nigra pars compacta (SNpc). It was found that when the recording electrodes were implanted at the level of the caudate nucleus (CN), typical patterns were obtained only when the stimulation electrode was located in the SNpc. When the stimulation electrode was fixed in the SNpc and four electrodes were simultaneously used to record depth profile from the caudate nucleus and the septum, the typical responses following stimulation were obtained only when electrodes were within the CN head. High frequency stimulation of the SNpc, which is known to alter dopamine content within the CN, caused a reversible diminution of responses in CN for 5-10 min. This observation was discussed in terms of terminal transmitter depletion.

The effects of cholinergic agents on morphine-induced circling behavior in the intact mouse

The effects of morphine on locomotor activity in mice was studied. It was shown that morphine in this species induces circling, a dose-dependent, stereotyped behavior. At high doses of morphine, mice engaged virtually exclusively in circling uninterrupted by other activities. The effect was modified by muscarinic agents. Blockade of muscarinic receptors with atropine potentiated circling while the muscarinic agonist, oxotremorine, attenuated it. The mixed muscarinic/nicotinic cholinergic agonist, physostigmine, had no effect on this behavior.