Opioid self-administration and REM sleep EEG power spectra

Sleep-mediated regulation of reward circuits: implications in substance use disorders

Our modern society suffers from both pervasive sleep loss and substance abuse-what may be the indications for sleep on substance use disorders (SUDs), and could sleep contribute to the individual variations in SUDs? Decades of research in sleep as well as in motivated behaviors have laid the foundation for us to begin to answer these questions. This review is intended to critically summarize the circuit, cellular, and molecular mechanisms by which sleep influences reward function, and to reveal critical challenges for future studies. The review also suggests that improving sleep quality may serve as complementary therapeutics for treating SUDs, and that formulating sleep metrics may be useful for predicting individual susceptibility to SUDs and other reward-associated psychiatric diseases.

Chronic morphine administration in cats: effects on sleep and EEG

Sleep-wakefulness and EEG responses to a chronic morphine treatment (2 mg/kg/day, IP, during 15 days) were studied in 8 cats provided with electrodes for EEG, EMG and EOG records. Results indicated that, in contrast to a resistance of the cats to exhibit overt signs of tolerance in the immediate behavioral and EEG responses to morphine, tolerance developed in sleep since: 1) there was a reduction in its onset latency after the initial insomnia period; 2) despite that the initial insomnia period was present throughout the treatment, compared to the effects of the first MS day, the total amount of both NREM sleep and REM sleep significantly increased in subsequent drug days, the total amount of REM sleep reached similar placebo values from day 5; 3) the restoration in the total amount of both sleep states was due to significant increases that occurred from day 5 after the first 6 hours of the MS injection. During the 19-24 hours after MS injections, increases of NREM and REM also resulted statistically significant compared to placebo values. A biphasic depressed and aroused response occurred during early withdrawal. REM sleep rebound was present after MS discontinuation and in the following week. Similarities with effects of opiate chronic administration in other species are discussed. These results support the potential use of the cat for the study of neural mechanisms involved in sleep chronic effects of opiates.

Opioid self-administration in rats: pharmacodynamics and pharmacokinetics

This article provides comparative data obtained during opioid self-administration in rats, using our EEG-EMG rat model of addiction. This model allows continuous recording of EEG and EMG activities and programming of intravenous drug injections. Comparative data on opioid self-administration patterns are presented. These studies on the association between EEG and behavioral correlates of opioid self-administration have contributed to the delineation of similarities and differences in pharmacodynamic and pharmacokinetic characteristics of opioids.

Power spectral analysis of electroencephalographic activity in kindled rats

Power spectral analysis of the resting EEG activity of amygdala kindled rats revealed a decrease of power in the 1- to 3-Hz band and an increase in the 4- to 6-Hz band compared with 3-Hz-stimulated and operated control animals. This effect was observed only in the stimulated but not the contralateral amygdala. The alteration in power seen shortly after kindling was still evident after a 1-month stimulation-free period.

Behavioural and spectrum power effects of opioid peptides in chicks

The effects of intracerebroventricular administration of beta-endorphin, dermorphin, D-ala2-methionine-enkephalinamide (DALA) and pentazocine, on behaviour, electrocortical activity and ECoG spectrum power in young chicks were studied. Beta-endorphin, dermorphin and DALA produced dose-dependent behavioural sedation and sleep accompanied by electrocortical high voltage slow wave activity and increase in total voltage power with a predominant increase in the lower bands of ECoG spectrum. Dermorphin was found significantly more potent than beta-endorphin and DALA since it was active at much lower doses. Behavioural and ECoG sleep evoked by opioid peptides were rapidly reversed by naloxone showing that these effects are mediated through an activation of specific opioid receptors. Doses of pentazocine equimolar with doses of dermorphin and beta-endorphin producing sleep did not affect behaviour and spectrum power whereas higher doses produced opposite effects, i.e., behavioural stimulation, pecking and increase in locomotor activity.

Spectral analysis of kindled hippocampal afterdischarges in lead-treated rats

Male rats were exposed to lead from parturition through weaning. When subjected to electrical hippocampal kindling as adults, although there were no alterations in the kindling rates, lead-treated animals were found to differ from controls in several other respects. In contrast to controls, lead-treated animals did not show an increase in afterdischarge (AD) duration with kindling, and the power spectrum of the AD did not shift to a higher peak frequency. There was a clear dose-related effect of lead on the spectra of the kindled AD, which in lead-treated groups was characterized by greater power in the low-frequency bands. These data indicate that long-lasting dysfunction can occur following a brief neonatal lead exposure. Power spectral techniques may be useful for future studies in neurotoxicology and epilepsy.

Self-administration of ketocyclazocine and ethylketocyclazocine by the rat

The purpose of the study was to assess possible substitution of either ketocyclazocine or ethylketocyclazocine for morphine in rats maintaining their own dependence by self-administration. Rats were prepared with indwelling IV cannulae, made tolerant to and physically dependent on morphine, then trained to lever press for morphine self-injections on a fixed ratio (FR) schedule of reinforcement. When either ketocyclazocine or ethylketocyclazocine was substituted for morphine, rats self-administered single injections of these kappa opioid agonists at relatively evenly spaced intervals over a 24-hr period. These self-injection patterns continued for up to at least 15 consecutive days. Substitution of saline for the kappa opioid agonists did not result in the emergence of a morphine-like abstinence syndrome. Differences in extent and intensity of withdrawal between morphine and these kappa opioid agonists indicate the involvement of separate receptor populations in the process of dependence on morphine and these kappa opioid agonists.

Electromyographic power spectral changes associated with the sleep-awake cycle and with diazepam treatment in the rat

Power spectral analysis was used to study temporalis muscle EMG activities during the sleep-awake cycle in the rat. EMG spectra derived from EMG during the states of slow-wave sleep. REM sleep and wakefulness demonstrated qualitative and quantitative differences. Diazepam treatment produced reductions in EMG spectral power during wakefulness. Thus, our experimental model allows qualitative and quantitative delineation of EMG activity associated with behavioral changes or drug treatments.

Electrophysiological evidence of concurrent dorsal raphe input to caudate, septum, habenula, thalamus hippocampus, cerebellum and olfactory bulb

Field potentials evoked by electrical stimulation of the dorsal raphe nucleus (DR) were recorded in eight forebrain structures in the rat. The areas were chosen chiefly for their anatomical connections to the DR and included the olfactory bulb (OB), caudate nucleus (CN), lateral septum (Spt), lateral habenula (Hb), parafascicularis (PF), ventral thalamus (VT), hippocampus-CA1 (Hipp), and cerebellum (CB). DR stimulation evoked an initial biphasic positive-negative wave form at similar latencies in each of the eight structures. A later positive-negative-positive wave was evoked in only six structures: CN, Spt, Hb, PF, VT, and Hipp. The amplitudes and latencies of the peaks of the later wave forms varied among structures. A depth profile recording procedure created by moving the DR stimulating electrode showed that the responses in the remote structures occurred only when the stimulating electrode was located in the DR. Bursting the DR at 20 Hz for 5-20 min caused a decrease in all components of the response. The evoked potential amplitude returned to baseline levels 5-30 min after cessation of stimulation. The results indicates that the dorsal raphe has a concurrent input to many areas of the brain receiving 5HT afferents and that DR stimulation can modulate the neuronal activity in these regions.

Self-administration of nalbuphine, butorphanol and pentazocine by morphine post-addict rats

The purpose of the study was to define possible self-administration of nalbuphine, butorphanol and pentazocine by morphine post-addict rats. Rats were prepared with permanent EEG and EMG electrodes and indwelling IV cannulae, made tolerant to and physically dependent on morphine, then trained to lever press for morphine IV self-injections on a fixed ratio (FR) 20 schedule of reinforcement. Rats were then spontaneously withdrawn from morphine. When these morphine post-addict rats were returned to the experimental cages three to four weeks later, they were found to reestablish self-administration of morphine as well as to establish self-administration of nalbuphine, butorphanol and pentazocine. Suppression of REM sleep for at least 30 min was apparent following self-injections of these agents. After the stabilization of self-injection patterns, withdrawal from nalbuphine and pentazocine was found to be associated with intense abstinence symptoms. However, withdrawal from morphine and butorphanol was not. It can be concluded that while drug-seeking behavior for the above narcotics in morphine post-addict rats was analogous as measured by self-administration, nalbuphine and butorphanol appeared to produce lower levels of physical dependence.

Acute heroin abstinence in man: IV. Sleep--waking state contingencies

This study investigated the effect of acute heroin withdrawal on the pattern of sleep--waking state sequences. Subjects included drug-dependent patients using pure heroin and drug-free controls. Electrophysiological data were recorded on a 24-hour per day basis for the first 5 - 7 days of withdrawal. EEG records were scored according to standard criteria. Marked increases in the sequential state changes occurred during withdrawal when progressing from awake-with-alpha, stage I, stage II and rapid eye movement (REM) sleep to the awake state. Heroin withdrawal also caused significant decreases in sequential state changes when proceeding from waking or light sleep states into deeper sleep states or into REM sleep. This study revealed that heroin withdrawal caused more abrupt transitions from quiet awake or sleeping conditions into the awake state and impeded progression into slow wave or REM sleep states.