Dynorphin, Dysphoria, and Dependence: the Stress of Addiction

Opioid system in L-DOPA-induced dyskinesia

L-3, 4-Dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID) is a major clinical complication in the treatment of Parkinson’s disease (PD). This debilitating side effect likely reflects aberrant compensatory responses for a combination of dopaminergic neuron denervation and repeated L-DOPA administration. Abnormal endogenous opioid signal transduction pathways in basal ganglia have been well documented in LID. Opioid receptors have been targeted to alleviate the dyskinesia. However, the exact role of this altered opioid activity is remains under active investigation. In the present review, we discuss the current understanding of opioid signal transduction in the basal ganglia and how the malfunction of opioid signaling contributes to the pathophysiology of LID. Further study of the opioid system in LID may lead to new therapeutic targets and improved treatment of PD patients.

Allostatic Mechanisms of Opioid Tolerance Beyond Desensitization and Downregulation

Mechanisms of opioid tolerance have focused on adaptive modifications within cells containing opioid receptors, defined here as cellular allostasis, emphasizing regulation of the opioid receptor signalosome. We review additional regulatory and opponent processes involved in behavioral tolerance, and include mechanistic differences both between agonists (agonist bias), and between μ- and δ-opioid receptors. In a process we will refer to as pass-forward allostasis, cells modified directly by opioid drugs impute allostatic changes to downstream circuitry. Because of the broad distribution of opioid systems, every brain cell may be touched by pass-forward allostasis in the opioid-dependent/tolerant state. We will implicate neurons and microglia as interactive contributors to the cumulative allostatic processes creating analgesic and hedonic tolerance to opioid drugs.

Self-reported Sleep Improvement in Buprenorphine MAT (Medication Assisted Treatment) Population

This is a prospective, naturalistic study to evaluate patient's report on sleep and depression in early recovery while receiving buprenorphine in Medication Assisted Treatment (MAT). 40 Subjects entering into MAT with buprenorphine/naloxonefor opioid dependence disorder were recruited. No change of concurrent treatment was made. Subjects were administered Sleep Scale from the Medical Outcomes Study (MOS-Sleep), a 5-item Supplemental Sleep Scale (SSS), and the Beck Depression Inventory II (BDI-II). The measures were administered at day 0 (baseline), 30, 60 and 90 days. The result showed that patients reported significant progressive improvements in three MOS-Sleep subscales: sleep disturbance, sleep indices I and II. The mean scores of SLPD4 (Sleep disturbance) at day 0, 30, 60, 90 were 62.4, 53.2, 53.3, and 48.4 respectively (p=0.0029). Similarly, subscores of SLP6 (Sleep Problem Index I) and SLP 9 (Sleep Problem Index II) were also significantly decreased over time (P=0.038 for SLP6 and p=0.007 for SLP9). BDI-II depression scores improved from "Moderate depression" at baseline to "Mild depression". The mean BDI score decreased from 24.2 to 17.0 after 90 days of treatment. Findings suggest that subjects reported improvement in both sleep and depression after initiating MAT with buprenorphine/naloxone.