HTR3B is associated with alcoholism with antisocial behavior and alpha EEG power—an intermediate phenotype for alcoholism and co-morbid behaviors

Alcohol use disorders (AUD) with co-morbid antisocial personality disorder (ASPD) have been associated with serotonin (5-HT) dysfunction. 5-HT3 receptors are potentiated by ethanol and appear to modulate reward. 5-HT3 receptor antagonists may be useful in the treatment of early-onset alcoholics with co-morbid ASPD. Low-voltage alpha electroencephalogram (EEG) power, a highly heritable trait, has been associated with both AUD and ASPD. A recent whole genome linkage scan in one of our samples, Plains American Indians (PI), has shown a suggestive linkage peak for alpha power at the 5-HT3R locus. We tested whether genetic variation within the HTR3A and HTR3B genes influences vulnerability to AUD with comorbid ASPD (AUD + ASPD) and moderates alpha power. Our study included three samples: 284 criminal alcoholic Finnish Caucasians and 234 controls; two independent community-ascertained samples with resting EEG recordings: a predominantly Caucasian sample of 191 individuals (Bethesda) and 306 PI. In the Finns, an intronic HTR3B SNP rs3782025 was associated with AUD + ASPD (P = .004). In the Bethesda sample, the same allele predicted lower alpha power (P = 7.37e⁻⁵). Associations between alpha power and two other HTR3B SNPs were also observed among PI (P = .03). One haplotype in the haplotype block at the 3′ region of the gene that included rs3782025 was associated with AUD + ASPD in the Finns (P = .02) and with reduced alpha power in the Bethesda population (P = .00009). Another haplotype in this block was associated with alpha power among PI (P = .03). No associations were found for HTR3A. Genetic variation within HTR3B may influence vulnerability to develop AUD with comorbid ASPD. 5-HT3R might contribute to the imbalance between excitation and inhibition that characterize the brain of alcoholics.     

Cerebral vascular responsiveness after experimental traumatic brain injury: the beneficial effects of delayed hypothermia combined with superoxide dismutase administration

OBJECT: Traumatic brain injury (TBI) induces cerebral vascular dysfunction reflected in altered responses to vasodilators such as acetylcholine and hypercapnia. It has been demonstrated that the use of either posttraumatic hypothermia or free radical scavengers offered vascular protection when those treatments were delivered early after the injury, losing efficacy when the initiation of either treatment was delayed. Because immediate posttraumatic treatment is not realistic in the clinical setting, the authors undertook this study to investigate whether the combination of delayed hypothermia and the delayed administration of the free radical scavenger superoxide dismutase (SOD) could result in improved vascular protection. METHODS: Male Sprague-Dawley rats were anesthetized and subjected to either an impact-acceleration or sham injury. Animals were treated either with hypothermia (32 degrees C) initiated 60 minutes after TBI, delayed SOD (60 U/ml) applied 90 minutes after TBI, or a combination of delayed hypothermia (32 degrees C) and delayed SOD (60 U/ml) applied 15 minutes prior to the cessation of hypothermia. In this investigation, the diameter of cerebral pial arterioles was measured at rest and then challenged with vasodilator acetylcholine and hypercapnia. Four vessels were assessed per animal prior to injury and then again up to 6 hours after injury. RESULTS: Delayed SOD treatment did not enhance vascular function, while delayed hypothermia treatment only partially preserved pial vascular function. However, the combination of delayed hypothermia and delayed SOD significantly preserved vascular function after the injury. CONCLUSIONS: The results of these studies demonstrate that delayed hypothermia partially preserves vascular function after TBI, while expanding the therapeutic window over which agents such as SOD can now provide enhanced protection.     

Inhibition of 5-HT1A receptor-dependent cell survival by cAMP/protein kinase A: role of protein phosphatase 2A and Bax

Serotonergic 5-HT(1A) receptor signaling leading to nuclear factor-kappaB (NF-kappaB) activation appears to be critical for cell survival. Adenylyl cyclase and protein kinase A (AC/PKA) are effectors of the 5-HT(1A) receptor that are inhibited by Galpha(i) subunits. Conversely, Gbetagamma(i) subunits downstream from the 5-HT(1A) receptor participate in the activation of extracellular signal-regulated kinases (ERK1/2), phosphatidylinositol 3-kinase (PI3K), Akt, and NF-kappaB. To model the contribution of pro- and antiapoptotic signaling cascades downstream of activated 5-HT(1A) receptor in cell survival, Chinese hamster ovarian (CHO) cells were employed that exogenously overexpress 5-HT(1A) receptors. Stimulation with the 5-HT(1A) receptor agonist 8-OH-DPAT and pharmacological agonists of AC induced PKA and protein phosphatase 2A (PP2A) activity, which in turn inhibited: Akt activity, IkappaBalpha degradation, nuclear translocation of NF-kappaB, and expression of X-linked inhibitor of apoptosis protein (XIAP/BIRC4). Pharmacological inhibition of PP2A with calyculin A potentiated Akt activity while attenuating ERK1/2 signaling via increased inhibitory phosphorylation of Raf (pSer259). In contrast, increased cAMP levels enhanced Bax translocation to the mitochondria, resulting in the release of cytochrome c, caspase-3 activation, and apoptosis induction. Our data suggest a central role of cAMP/PKA-dependent PP2A in shifting the homeostasis of intracellular signaling downstream of activated 5-HT(1A) receptor toward cell death in biological systems linked to neuropsychiatric disorders.     

Neurophysiological and genetic distinctions between pure and comorbid anxiety disorders

Anxiety disorders are often comorbid with major depression (MD) and alcohol use disorders (AUD). Two common functional polymorphisms in catechol-O-methyltransferase (COMT Val158Met) and brain-derived neurotrophic factor (BDNF Val66Met) genes have been implicated in the neurobiology of anxiety and depression. We hypothesized that attentional response and working memory (auditory P300 event-related potential and Weschler Adult Intelligence Scale, Revised digit symbol scores) as well as genetic vulnerability would differ between pure anxiety disorders and comorbid anxiety. Our study sample comprised 249 community-ascertained men and women with lifetime DSM-III-R diagnoses. We analyzed groups of participants with pure anxiety disorders, pure MD, pure AUD, comorbid anxiety, and no psychiatric disorder. Participants were well at the time of testing; state anxiety and depressed mood measures were at most only mildly elevated. Individuals with pure anxiety disorders had elevated P300 amplitudes (P=0.0004) and higher digit symbol scores (P<0.0001) compared with all the other groups. Individuals with comorbid anxiety had the greatest proportion of COMT Met158 and BDNF Met66 alleles (P=0.009) as well as higher harm avoidance-neuroticism (P<0.0005) than all other groups. Our results suggest that there may be two vulnerability factors for anxiety disorders with differing genetic susceptibility: (a) heightened attention and better working memory with mildly elevated anxiety-neuroticism, a constellation that may be protective against other psychopathology; and (b) poorer attention and working memory with greater anxiety-neuroticism, a constellation that may also increase vulnerability to AUD and MD. This refinement of the anxiety phenotype may have implications for therapeutic interventions.     

Multilaboratory testing of antifungal combinations against a quality control isolate of Candida krusei

Candida krusei ATCC 6258 was tested by eight laboratories using 96-well plates containing checkerboard pairwise combinations of amphotericin B (AMB), posaconazole (PSC), caspofungin (CSP), and voriconazole (VRC). The methodology led to reproducible results across the laboratories. All drug combinations yielded MICs lower than the MICs of any two drugs tested singly, and combinations of AMB, PSC, CSP, and VRC were indifferent (no antagonism) by summations of fractional inhibitory concentration.     

Endoplasmic reticulum stress and liver injury

Endoplasmic reticulum stress, initiated by protein overload or malfolding, activates a complex network of interacting and parallel responses that dampen the stress. However, when the protective response is insufficient, a set of responses leads to apoptosis. Coupled with the latter are promotion of lipid synthesis and proinflammatory responses. Evidence has been mounting for an important role of the endoplasmic reticulum (ER) stress response in the pathogenesis of chronic viral hepatitis, insulin resistance and nonalcoholic fatty liver disease, ischemia-reperfusion injury, genetic disorders of protein malfolding, and alcoholic liver disease. In the latter, a key candidate for inducing ER stress is hyperhomocysteinemia. Betaine treatment promotes removal of homocysteine and prevents ER stress, fatty liver, and apoptosis in a mouse model of alcohol-induced liver disease. With increasing interest in the potential role of ER stress in liver disease, greater understanding of pathophysiology, prevention, and treatment of liver disease is anticipated.