Joseph A. Kim

The Prevalence of Anxiety and Mood Problems among Children with Autism and Asperger Syndrome

The objective of this study was to report on the prevalence and correlates of anxiety and mood problems among 9- to 14- year-old children with Asperger syndrome (AS) and high-functioning autism. Children who received a diagnosis of autism (n 40) or AS (n 19) on a diagnostic interview when they were 4 to 6 years of age were administered a battery of cognitive and behavioural measures. Families were contacted roughly 6 years later (at mean age of 12 years) and assessed for evidence of psychiatric problems including mood and anxiety disorders. Compared with a sample of 1751 community children, AS and autistic children demonstrated a greater rate of anxiety and depression problems. These problems had a significant impact on their overall adaptation. There were, however, no differences in the number of anxiety and mood problems between the AS and autistic children within this high-functioning cohort. The number of psychiatric problems was not correlated with early autistic symptoms but was predicted to a small extent by early verbal/non-verbal IQ discrepancy scores. These data indicate that high-functioning PDD children are at greater risk for mood and anxiety problems than the general population but the correlates and risk factors for these comorbid problems remain unclear.

Pavlovian psychopharmacology: the associative basis of tolerance.

The Pavlovian conditioning analysis of drug tolerance emphasizes that cues present at the time of drug administration become associated with drug-induced disturbances. These disturbances elicit unconditional responses that compensate for the pharmacological perturbation. The drug-compensatory responses eventually come to be elicited by drug-paired cues. These conditional compensatory responses (CCRs) mediate tolerance by counteracting the drug effect when the drug is administered in the presence of cues previously paired with the drug. If the usual predrug cues are presented in the absence the drug, the unopposed CCRs are evident as withdrawal symptoms. Recent findings elucidate intercellular and intracellular events mediating CCRs and indicate the importance of internal stimuli (pharmacological cues and interoceptive cues inherent in self-administration) to the acquisition of drug tolerance and the expression of withdrawal symptoms.

DRUG-ONSET CUES AS SIGNALS : INTRAADMINISTRATION ASSOCIATIONS AND TOLERANCE

On the basis of a conditioning analysis of drug tolerance, drug-associated cues become associated with the drug effect. These cues elicit conditional compensatory responses and modulate the expression of tolerance. Although there are many findings consistent with the conditioning analysis of tolerance, there also are contrary findings. The results of these experiments suggest that some of the apparently contradictory findings result because interoceptive pharmacological cues, as well as exteroceptive environmental cues, are paired with a drug effect. That is, within each administration, early drug-onset cues may become associated with the later, larger drug effect, and these pharmacological cues may overshadow simultaneously present environmental cues. We demonstrate the contribution of such intraadministration associations to tolerance to the analgesic effect of morphine and to the expression of conditional compensatory hyperalgesia.

Intraadministration Associations: Conditional Hyperalgesia Elicited by Morphine Onset Cues

There is evidence that exteroceptive cues associated with drug administration elicit conditional compensatory responding (e.g., hyperalgesia in organisms with a history of morphine administration). Recently it has become apparent that, within each administration, interoceptive early-drug onset cues (DOCs) may become associated with the later, larger drug effect (intraadministration associations). The present experiments evaluated DOC-elicited conditional hyperalgesia in rats intravenously infused with morphine. The results indicated that DOC-elicited hyperalgesia contributes to tolerance to the analgesic effect of morphine, and such DOC-elicited hyperalgesia is an associative phenomenon, rather than a sensitized response to the opiate. The findings suggest that associative analyses of tolerance should acknowledge the conditional responding elicited by DOCs, and extinction-based addiction treatments should incorporate extinction of DOC-elicited conditional responding.

Increased response to morphine in mice lacking protein kinase C epsilon

The protein kinase C (PKC) family of serine–threonine kinases has been implicated in behavioral responses to opiates, but little is known about the individual PKC isozymes involved. Here, we show that mice lacking PKCɛ have increased sensitivity to the rewarding effects of morphine, revealed as the expression of place preference and intravenous self‐administration at very low doses of morphine that do not evoke place preference or self‐administration in wild‐type mice. The PKCɛ null mice also show prolonged maintenance of morphine place preference in response to repeated testing when compared with wild‐type mice. The supraspinal analgesic effects of morphine are enhanced in PKCɛ null mice, and the development of tolerance to the spinal analgesic effects of morphine is delayed. The density of μ‐opioid receptors and their coupling to G‐proteins are normal. These studies identify PKCɛ as a key regulator of opiate sensitivity in mice.

Biomarkers of morphine tolerance and dependence are prevented by morphine-induced endocytosis of a mutant μ-opioid receptor

Growing evidence shows that trafficking of the μ‐opioid receptor (MOR) is a critical process in functional recovery from desensitization following ac‐ tivation and plays important roles in morphine toler‐ ance and dependence largely because of the failure of morphine to promote such trafficking. However, mor‐ phine tolerance and dependence are believed to be mediated by multiple mechanisms, including well‐doc‐ umented biochemical changes in cAMP activity, N‐ methyl‐D‐aspartate receptors (NMDARs), glucocorti‐ coid receptors (GRs), and c‐fos. Here, we assess the consequences of promoting morphine‐induced endocy‐ tosis on these biochemical changes utilizing a knock‐in mouse model, RMOR, in which MORs undergo mor‐ phine‐induced endocytosis. Chronic morphine treat‐ ment of wild‐type (WT) mice promoted superactivation of adenylyl cyclase, alterations in NMDARs, and up‐ regulation of GR and c‐fos in distinct brain regions. Notably, none of these biochemical changes occurred in the RMOR‐knock‐in mice. Together, these data demonstrate that morphine tolerance and dependence are mediated by multiple biochemical mechanisms and that MOR endocytosis plays a critical role in each of these mechanisms.—He, L., Kim, J. A., Whistler, J. L. Biomarkers of morphine tolerance and dependence are prevented by morphine‐induced endocytosis of a mu‐ tant μ‐opioid receptor. FASEBJ. 23, 4327‐4334 (2009). www.fasebj.org

Methadone antinociception is dependent on peripheral opioid receptors

UNLABELLED Morphine and methadone are both high-affinity, potent mu-opioid peptide (MOP) receptor analgesics. In this report, we compared the antinociceptive potencies of these 2 drugs when administered subcutaneously (s.c.), intrathecally (i.t.), or intracerebroventricularly (i.c.v.) in both rat and mouse, using the tail-flick assay. We found that both morphine and methadone were potently antinociceptive when the drugs were administered s.c., showing comparable AD50 values in both species. However, the antinociception produced by methadone, when it was administered centrally, was much weaker than that produced by centrally administered morphine. Specifically, the AD50 value for methadone antinociception was more than 30-fold higher at both the i.t. and i.c.v. sites in mouse and not measurable in rat. Naloxone methiodide (NLX-M), a peripherally restricted antagonist, was used to further examine the relative contribution of central versus peripheral sites to morphine and methadone antinociception. NLX-M, when administered s.c., blocked the antinociceptive effect of either systemically or centrally administered methadone but had little effect on the antinociception produced by centrally administered morphine. Furthermore, centrally administered NLX-M significantly blocked antinociception produced by centrally administered morphine but not that produced by centrally administered methadone. Together, these results suggest that methadone antinociception is significantly dependent on an action of the drug at peripheral sites and could provide novel insight into the neural mechanisms that distinguish morphine versus methadone antinociception. PERSPECTIVE Methadone is often used as an alternative for pain management. The present study shows that a peripheral action plays a crucial role in methadone antinociception. This finding could have significant clinical relevance for the use of methadone versus morphine for the treatment of certain types of pain.

A Potent Immunomodulatory Compound, (S,R)-3-Phenyl-4,5-dihydro-5-isoxasole Acetic Acid, Prevents Spontaneous and Accelerated Forms of Autoimmune Diabetes in NOD Mice and Inhibits the Immunoinflammatory Diabetes Induced by Multiple Low Doses of Streptozotocin in CBA/H Mice

(S,R)-3-Phenyl-4,5-dihydro-5-isoxasole acetic acid (VGX-1027) is an isoxazole compound that exhibits various immunomodulatory properties. The capacity of VGX-1027 to prevent interleukin (IL)-1β plus interferon-γ-induced pancreatic islet death in vitro prompted us to evaluate its effects on the development of autoimmune diabetes in preclinical models of human type 1 diabetes mellitus (T1D). Administration of VGX-1027 to NOD mice with spontaneous or accelerated forms of diabetes induced either by injection of cyclophosphamide or by transfer of spleen cells from acutely diabetic syngeneic donors markedly reduced the cumulative incidence of diabetes and insulitis. In addition, VGX-1027 given either i.p. or p.o. to CBA/H mice made diabetic with multiple low doses of streptozotocin successfully counteracted the development of destructive insulitis and hyperglycemia. The animals receiving VGX-1027 exhibited reduced production of the proinflammatory mediators tumor necrosis factor-α, IL-1β, macrophage migration inhibitory factor, and inducible nitric-oxide synthase-mediated nitric oxide generation in both pancreatic islets and peripheral compartments. These results indicate that VGX-1027 probably exerts its antidiabetogenic effects by limiting cytokine-mediated immunoinflammatory events, leading to inflammation and destruction of pancreatic islets. VGX-1027 seems worthy of being considered as a candidate drug in the development of new therapeutic strategies for the prevention and early treatment of T1D.

A novel knock-in mouse reveals mechanistically distinct forms of morphine tolerance

The role of μ-opioid receptor (MOR) down-regulation in opioid tolerance remains controversial. In this study, we used a novel knock-in mouse to examine how changing the extent of MOR down-regulation alters the development of morphine tolerance. These mice express a mutant MOR, degrading MOR (DMOR), that differs from the wild-type (WT) MOR in two ways: 1) unlike the recycling WT MOR, the mutant DMOR is targeted for degradation after its internalization, thus facilitating down-regulation; and 2) unlike the WT MOR, DMOR is efficiently internalized in response to morphine activation. We found that both WT MOR and DMOR mice develop tolerance to morphine, but DMOR mice exhibit a more rapid onset of tolerance and show receptor down-regulation. WT MOR mice develop morphine tolerance more slowly but even once profoundly tolerant show no receptor down-regulation. Furthermore, WT mice show significantly more morphine dependence than DMOR mice after long-term treatment as indicated by withdrawal. Taken together these data indicate that tolerance mediated by receptor down-regulation manifests differently both at the behavioral and biochemical level than does the actual morphine tolerance that occurs in WT mice and that loss of receptor function is not a major contributor to morphine tolerance in WT MOR mice.

G-protein coupled receptor kinase (GRK)-5 regulates proliferation of glioblastoma-derived stem cells

Glioblastoma multiforme (GBM) is a grade IV malignant brain tumor with high mortality and has been well known to involve many molecular pathways, including G-protein coupled receptor (GPCR)-mediated signaling (such as epithelial growth factor receptor [EGFR] and platelet derived growth factor receptor [PDGFR]). G protein-coupled receptor kinases (GRK) directly regulate GPCR activity by phosphorylating activated agonist-bound receptors to desensitize signaling and internalize receptors through beta-arrestins. Recent studies in various cancers, including prostate and breast cancer, have highlighted the role of change in GRK expression to oncogenesis and tumor proliferation. In this study, we evaluated the expression of GRK5 in grade II to grade IV glioma specimens using immunohistochemistry and found that GRK5 expression levels are highly correlated with aggressiveness of glioma. We used culture conditions to selectively promote the growth of either glioblastoma cells with stem cell markers (GSC) or differentiated glioblastoma cells (DGC) from fresh GBM specimens. GSC are known to be highly invasive and mobile, and have the capacity to self-renew and are more resistant to chemotherapy and radiation compared to differentiated populations of GBM. We examined the expression of GRK5 in these two sets of culturing conditions for GBM cells and found that GRK5 expression is upregulated in GSC compared to differentiated GBM cells. To better understand the role of GRK5 in GBM-derived stem cells, we created stable GRK5 knockdown and evaluated the proliferation rate. Using an ATP chemiluminescence assay, we show, for the first time, that knocking down the expression of GRK5 decreased the proliferation rate of GSC in contrast to control.