Changes in migraine interictal burden following treatment with galcanezumab: Results from a phase III randomized, placebo-controlled study.

OBJECTIVE: To evaluate changes in interictal burden with galcanezumab versus placebo in patients with episodic (EM) or chronic migraine (CM). BACKGROUND: The disruptive effects of migraine occur both during attacks (ictal period) and between attacks (interictal period), affecting work, school, family, and social life. Migraine clinical trials typically assess ictal burden endpoints, neglecting interictal burden. METHODS: CONQUER was a 3-month, double-blind study that randomized adult patients with EM or CM who had experienced failure of two to four standard-of-care migraine preventive medication categories to receive monthly galcanezumab (n = 232) or placebo (n = 230), followed by 3 months of open-label galcanezumab. The mean change in interictal burden, a secondary objective, was measured using the four-item Migraine Interictal Burden Scale (MIBS-4). The total score for MIBS-4 can range from zero to 12, with scores ≥5 indicating severe interictal burden. Post hoc analyses evaluated shifts in MIBS-4 severity categories and item-level improvement. RESULTS: The MIBS-4 total score indicated severe interictal burden at baseline (mean [SD]: all patients, 5.5 [3.5]; EM, 5.0 [3.4]; CM, 6.2 [3.5]). Reductions in the MIBS-4 score were significantly greater with galcanezumab versus placebo at Month 3 (mean [SE]: all patients -1.9 [0.2] vs. -0.8 [0.2], p < 0.0001; EM, -1.8 [0.3] vs. -1.1 [0.3], p = 0.033; CM, -1.8 [0.4] vs. -0.3 [0.4], p < 0.001), with further improvement at Month 6 after all patients had received galcanezumab (mean [SE]: all patients, -2.4 [0.2] vs. -2.0 [0.2]; EM, -2.3 [0.3] vs. -2.2 [0.3]; CM, -2.1 [0.4] vs. -1.5 [0.4]). The percentage of patients with severe interictal burden decreased substantially for the galcanezumab-treated patients, from 59% (137/232) at baseline to 27% (58/217) at Month 6 (EM from 51% [70/137] to 23% [30/131]; CM from 71% [67/95] to 33% [28/86]). CONCLUSION: In addition to the known efficacy of galcanezumab in the ictal period, these findings suggest treatment with galcanezumab results in a significant reduction in interictal burden.

Fragile X mental retardation protein regulates synaptic and behavioral plasticity to repeated cocaine administration.

Repeated cocaine exposure causes persistent, maladaptive alterations in brain and behavior, and hope for effective therapeutics lies in understanding these processes. We describe here an essential role for fragile X mental retardation protein (FMRP), an RNA-binding protein and regulator of dendritic protein synthesis, in cocaine conditioned place preference, behavioral sensitization, and motor stereotypy. Cocaine reward deficits in FMRP-deficient mice stem from elevated mGluR5 (or GRM5) function, similar to a subset of fragile X symptoms, and do not extend to natural reward. We find that FMRP functions in the adult nucleus accumbens (NAc), a critical addiction-related brain region, to mediate behavioral sensitization but not cocaine reward. FMRP-deficient mice also exhibit several abnormalities in NAc medium spiny neurons, including reduced presynaptic function and premature changes in dendritic morphology and glutamatergic neurotransmission following repeated cocaine treatment. Together, our findings reveal FMRP as a critical mediator of cocaine-induced behavioral and synaptic plasticity.

Repeated methamphetamine administration differentially alters fos expression in caudate-putamen patch and matrix compartments and nucleus accumbens.

BACKGROUND: The repeated administration of psychostimulant drugs produces a persistent and long-lasting increase ("sensitization") in their psychomotor effects, which is thought to be due to changes in the neural circuitry that mediate these behaviors. One index of neuronal activation used to identify brain regions altered by repeated exposure to drugs involves their ability to induce immediate early genes, such as c-fos. Numerous reports have demonstrated that past drug experience alters the ability of drugs to induce c-fos in the striatum, but very few have examined Fos protein expression in the two major compartments in the striatum--the so-called patch/striosome and matrix. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we used immunohistochemistry to investigate the effects of pretreatment with methamphetamine on the ability of a subsequent methamphetamine challenge to induce Fos protein expression in the patch and matrix compartments of the dorsolateral and dorsomedial caudate-putamen and in the ventral striatum (nucleus accumbens). Animals pretreated with methamphetamine developed robust psychomotor sensitization. A methamphetamine challenge increased the number of Fos-positive cells in all areas of the dorsal and ventral striatum. However, methamphetamine challenge induced Fos expression in more cells in the patch than in the matrix compartment in the dorsolateral and dorsomedial caudate-putamen. Furthermore, past experience with methamphetamine increased the number of methamphetamine-induced Fos positive cells in the patch compartment of the dorsal caudate putamen, but not in the matrix or in the core or shell of the nucleus accumbens. CONCLUSIONS/SIGNIFICANCE: These data suggest that drug-induced alterations in the patch compartment of the dorsal caudate-putamen may preferentially contribute to some of the enduring changes in brain activity and behavior produced by repeated treatment with methamphetamine.

Methamphetamine-induced structural plasticity in the dorsal striatum.

Repeated exposure to psychostimulant drugs produces long-lasting changes in dendritic structure, presumably reflecting a reorganization in patterns of synaptic connectivity, in brain regions that mediate the psychomotor activating and incentive motivational effects of these drugs, including the nucleus accumbens and prefrontal cortex. However, repeated exposure to psychostimulant drugs also facilitates a transition in the control of some behaviors from action-outcome associations to behavior controlled by stimulus-response (S-R) habits. This latter effect is thought to be due to increasing engagement and control over behavior by the dorsolateral (but not dorsomedial) striatum. We hypothesized therefore that repeated exposure to methamphetamine would differentially alter the density of dendritic spines on medium spiny neurons (MSNs) in the dorsolateral vs. dorsomedial striatum. Rats were treated with repeated injections of methamphetamine, and 3 months later dendrites were visualized using Sindbis virus-mediated green fluorescent protein (GFP) expression in vivo. We report that prior exposure to methamphetamine produced a significant increase in mushroom and thin spines on MSNs in the dorsolateral striatum, but a significant decrease in mushroom spines in the dorsomedial striatum. This may be due to changes in the glutamatergic innervation of these two subregions of the dorsal striatum. Thus, we speculate that exposure to psychostimulant drugs may facilitate the development of S-R habits because this reorganizes patterns of synaptic connectivity in the dorsal striatum in a way that increases control over behavior by the dorsolateral striatum.

Locomotor sensitization to cocaine is associated with increased Fos expression in the accumbens, but not in the caudate.

Behavioral sensitization following repeated intermittent cocaine administrations is thought to involve alterations in cocaine regulation of neural activity within the accumbens and caudate brain regions. Although Fos immunohistochemistry and c-fos in situ hybridization have frequently been used to assess changes in cocaine-induced neural activity following prior cocaine exposure, these techniques have rarely been used to examine neural activity in the accumbens of behaviorally sensitized animals. In the present experiment, we compared the ability of increasing doses of cocaine to induce Fos in the accumbens and caudate of rats following a treatment procedure (7 once daily injections of 15 mg/kg of cocaine or the saline vehicle) shown to produce robust and persistent (1 week) locomotor sensitization. In sensitized animals, there was a leftward shift in the dose-response curve for cocaine induction of Fos in the accumbens, but not in the caudate. These results provide the first parametric evidence for sensitization of cocaine-induced Fos expression in the accumbens.

Acute administration of cocaine regulates the phosphorylation of serine-19, -31 and -40 in tyrosine hydroxylase.

Acute cocaine can inhibit catecholamine biosynthesis by regulating the enzymatic activity of tyrosine hydroxylase via alterations in the phosphorylation state of the enzyme. The mechanisms underlying acute cocaine-dependent regulation of tyrosine hydroxylase phosphorylation have not been determined. In this study, 0, 15 or 30 mg/kg cocaine was administered intraperitoneally to rats and the phosphorylation state of tyrosine hydroxylase in the brain was examined using antibodies specific for the phosphorylated forms of serine-19, -31 and -40 in tyrosine hydroxylase. In the caudate and nucleus accumbens, cocaine dose-dependently decreased the levels of phosphorylated serine-19, -31 and -40. In the ventral tegmental area, the levels of phosphorylated serine-19, but not serine-31 and -40, were decreased by 15 and 30 mg/kg cocaine. In the amygdala, the levels of phosphorylated serine-19, but not serine-31 or -40, were decreased. The functional effects of these alterations in phosphorylation state were assessed by measuring tyrosine hydroxylase activity in vivo (accumulation of DOPA after administration of the decarboxylase inhibitor NSD-1015). Acute administration of 30 mg/kg cocaine significantly decreased l-DOPA production in caudate and accumbens but not in amygdala. These data suggest that the phosphorylation of serine-31 or -40, but not serine-19, is involved in the regulation of tyrosine hydroxylase activity by acute cocaine.