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Alcohol dependence continues to be an important health concern and animal models are critical to furthering our understanding of this complex disease. A hallmark feature of alcoholism is a significant increase in alcohol drinking over time. While several different animal models of excessive alcohol (ethanol) drinking exist for mice and rats, a growing number of laboratories are using a model that combines chronic ethanol exposure procedures with voluntary ethanol drinking with mice as experimental subjects. In the last years several experimental evidences have shown an involvement of opioid system in alcoholism.

Exposure to repeated cycles of ethanol intoxication and withdrawal triggers long-lasting neural and behavioral plasticity in experimental animals that appear relevant for modeling human alcoholism, such as increased ethanol preference and behavioral sensitivity to stress. Also, ethanol exposure induces tolerance in human and experimental animals, and after repeated administration, behavioral sensitization. Here, we asked whether our experimental paradigm of prolonged intermittent cyclic exposure to ethanol vapor induces long-lasting changes in tolerance and its stimulant properties. Post-dependent and control rats were injected with a hypnotic dose of ethanol (3 g/kg) and the loss of righting refl ex (LORR) was recorded. Blood ethanol levels (BLA) were monitored and elimination rate was calculated. The effect on locomotor activity induced by acute ethanol challenge (0.5 mg/kg) was registered in habituated animals. Furthermore, we studied neuroplasticity in systems related to these behaviors. We find a signifi cant decrease of LORR and increased ethanol-induced locomotion in post-dependent animals, while BLA or ethanol metabolism was not different from controls. These results give further validity to the cyclic exposure paradigm as a model of ethanol dependence and support its value for treatment development.

Development of a HPLC with colulometric detection methodology to measure olanzapine (OLA) and 4-N-desmethylolanzapine (DMO) levels in specific areas of rat brain after a single dose of OLA. Preliminary results are satisfactory in terms of sensitivity and selectivity.

Beta-arrestin 2 is a multifunctional key component of the G-protein coupled receptor complex and is involved in l-opiate and dopamine D2 receptor signalling, both of which are thought to mediate the rewarding effects of ethanol consumption. We identified elevated expression and of the beta-arrestin 2 gene (Arrb2) in the striatum and the hippocampus of ethanol preferring AA rats compared to their non-preferring counterpart ANA line. Differential mRNA expression was accompanied by different levels of Arrb2 protein. The elevated expression was associated with a 7-marker haplotype in complete linkage disequilibrium, which segregated fully between the lines, and was unique to the preferring line. These findings were functionally validated using mice lacking Arrb2, which displayed both reduced voluntary ethanol consumption and ethanol induced psychomotor stimulation. Our results demonstrate that beta-arrestin 2 modulates acute responses to ethanol and is an important mediator of ethanol reward.

Exposure to repeated cycles of ethanol intoxication and withdrawal results in a well characterized persistent post-dependent increase in excessive voluntary ethanol consumption and behavioral sensitivity to stress. We have previously described some molecular neuroadaptations that contribute to these behavioral traits. Formation of new neurons in the adult brain, or adult neurogenesis, is related to stress responsiveness, and previous work has established that it is modulated by ethanol intoxication and withdrawal. Here, we asked whether adult neurogenesis is altered in the post-dependent state, in a manner that could contribute to the functional phenotype observed in this condition. To this end, we studied cell proliferation and neurogenesis in the subgranular zone of the dentate gyrus (SGZ) and in the subventricular zone lining the lateral ventricle (SVZ) in rats over a period of 3 weeks following a previously described 7 week intermittent ethanol vapor exposure to induce dependence, and compared to controls without a history of ethanol exposure. A single dose of 5-bromo-2-deoxyuridine (BrdU, 200 mg/kg, i.p.) was administered 4-5 h prior to euthanasia on day 0, 3, 7 and 21 post induction of dependence (abstinence days). Proliferating precursor cells incorporate the mitotic marker BrdU and were identified using immunohistochemistry in SVZ and SGZ. In agreement with prior work, ethanol exposure decreased density and number of proliferating cells by 70 % in both the SVZ (p

Pharmacological and genetic interference with the renin angiotensin system (RAS) seems to alter voluntary ethanol consumption. Furthermore, increased gene expression of angiotensinogen (Agt) was consistently found in the brain of mouse (HAP) and rat (P, AA) lines selectively bred for high ethanol preference compared to their respective controls. Agt appears to be a node in gene-gene interactions regulating ethanol intake. However, understanding the influence of the RAS on ethanol dependence and its treatment requires modeling the neuroadaptations that occur with prolonged exposure to ethanol. Increased ethanol consumption was induced in rats through repeated cycles of intoxication and withdrawal. Expression of angiotensinogen, angiotensin-converting enzyme, and the angiotensin II receptor, AT1a was examined by quantitative RT-PCR. Increased ethanol consumption following a history of dependence was associated with increased angiotensinogen expression in medial prefrontal cortex, but not in nucleus accumbens or amygdala. Increased angiotensinogen expression also demonstrates that the astroglia is an integral part of the plasticity underlying the development of dependence. The effects of low central RAS activity on increased ethanol consumption were investigated using either spirapril, a blood-brain barrier-penetrating inhibitor of angiotensin-converting enzyme, or transgenic rats (TGR(ASrAOGEN)680) with reduced central angiotensinogen expression. Spirapril reduced ethanol intake in dependent rats compared to controls. After induction of dependence, TGR(ASrAOGEN)680 rats had increased ethanol consumption but to a lesser degree than Wistar rats with the same history of dependence. These data suggest that the central RAS is sensitized in its modulatory control of ethanol consumption in the dependent state, but pharmacological or genetic blockade of the system appears to be insufficient to halt the progression of dependence.

AA and ANA rats are one of the earliest and well established rodent models for ethanol preference. Several candidate genes have been suggested to confer genetic susceptibility for alcoholism in these lines including mitogen-activated protein kinases, Akt/PKB and GSK-3 pathways. The aim of the study was to compare the protein levels and phopshorylation of ERK 1/2, Akt and GSK-3 in AA and ANA rats under basal condition and after acute ethanol challenge. Animals were injected with either ethanol (1.5 g/kg) or saline and killed 20 or 45 minutes after injection. Brains were frozen and dissected, nucleus accumbens (NAcc) and cingulate cortex (CCx) were extracted and subject to immunobloting with total and phosphospecifi c antibodies. Baseline differences in ERK 1/2 phopshorylation were discovered between AA and ANA lines. Intraperitoneal injection of ethanol (1.5 g/kg) induced a rapid and transient decrease in ERK 1/2 phosphorylation in both CCx and NAcc within 20 minutes which was already reverting towards control levels at the 45 minute time point. There was no change in the total ERK levels. Phosphorylation of both GSK-3 and Akt in CCx of AA rats was increased 45 minutes after ethanol injection, however no changes were found in NAcc. In ANA rats there were no statistically signifi cant changes in all structures. Thus, AA rats are more susceptible to acute effects of ethanol involving some of the mitogen-activated protein kinases, Akt/PKB and GSK-3 pathways, and these differences are more prominent in the CCx compared to the NAcc.

Endocannabinoid signaling has recently been implicated in ethanol-seeking behavior. We analyzed the expression of endocannabinoid-related genes in key brain regions of reward and dependence, and compared them between the alcohol-preferring AA (Alko Alcohol) and nonpreferring ANA (Alko Non-Alcohol) rat lines. A decreased expression of fatty acid amidohydrolase (FAAH), the main endocannabinoid-degrading enzyme, was found in prefrontal cortex (PFC) of AA rats, and was accompanied by decreased enzyme activity in this region. Binding of the endocannabinoid-cannabinoid 1 (CB1) receptor ligand 3[H]SR141716A, and [35S]GTPitalic gammaS incorporation stimulated by the CB1 agonist WIN 55,212-2 were downregulated in the same area. Together, this suggests an overactive endocannabinoid transmission in the PFC of AA animals, and a compensatory downregulation of CB1 signaling. The functional role of impaired FAAH function for alcohol self-administration was validated in two independent ways. The CB1 antagonist SR141716A potently and dose-dependently suppressed self-administration in AA rats when given systemically, or locally into the PFC, but not in the striatum. Conversely, intra-PFC injections of the competitive FAAH inhibitor URB597 increased ethanol self-administration in nonselected Wistar rats. These results show for the first time that impaired FAAH function may confer a phenotype of high voluntary alcohol intake, and point to a FAAH both as a potential susceptibility factor and a therapeutic target.

Tolerance to alcohol effects is one of the defining features of clinical alcohol dependence. Here, we hypothesized that the post-dependent state may include tolerance to sedative-hypnotic alcohol actions. To address this question, we used a recently developed animal model in which repeated cycles of alcohol intoxication and withdrawal trigger long-lasting behavioral plasticity. This animal model shares important features with the clinical condition. Animals were exposed to 7 weeks of intermittent alcohol vapor, allowed to recover for 3 weeks, and tested in protracted abstinence to exclude contributions from acute withdrawal. Post-dependent and control rats were injected with a hypnotic dose of alcohol (3 g/kg), and the loss of righting reflex (LORR) was recorded, blood alcohol levels were monitored, and the elimination rate was calculated. Post-dependent animals showed a decrease in LORR. Alcohol metabolism and elimination kinetics did not differ between groups. In conclusion, a history of alcohol dependence induces long-lasting hypnotic tolerance. This process may play an important role in maintaining the dependent state.

Mitogen-activated and extracellular regulated kinase (MEK) and extracellular signal-regulated protein kinase (ERK) pathways may underlie ethanol-induced neuroplasticity. Here, the MEK inhibitor UO126 was used to probe the role of MEK/ERK signaling for the cellular response to an acute ethanol challenge in rats with or without a history of ethanol dependence. Ethanol (1.5 g/kg, i.p.) induced c-fos expression in brain regions associated both with rewarding and stressful ethanol actions. Under non-dependent conditions, alcohol-induced c-fos expression was generally not affected by MEK inhibition, with the exception of medial amygdala (MeA), and a similar pattern in the paraventricular nucleus (PVN). In contrast, following a history of dependence, a markedly suppressed c-fos response to acute ethanol was found in orbitofrontal cortex (OFC) and nucleus accumbens shell (AcbSh), key components of circuitry mediating positive drug reinforcement. The suppressed ethanol response in these regions was returned to normal by pre-treatment with UO126, demonstrating a recruitment of an ERK mediated inhibitory regulation in the post-dependent state. Conversely, in brain areas involved in stress responses (MeA, PVN), a MEK/ERK mediated cellular activation by acute ethanol was lost following a history of dependence. These data reveal highly region-specifi c neuroadaptations encompassing the MEK/ERK pathway in ethanol dependence. Recruitment of MEK/ERK mediated suppression of the ethanol response in OFC and AcbSh may refl ect devaluation of ethanol as a reinforcer, while loss of a MEK/ERK mediated response in MeA and PVN may reflect tolerance to its aversive actions. These two neuroadaptations could act in concert to facilitate progression into ethanol dependence.

With rising rates of alcohol consumption acute and chronic damage from alcohol is expected to increase all over the world. Habitual excessive alcohol consumption is associated with pathological effects on bone. The aim of the present in vitro study was to investigate comparatively the proliferation and synthetic activity of osteoblasts (OB) isolated from the trabecular bone of rats previously exposed to 7-week intermittent exposure to ethanol vapor, sham-aged rats and long-term estrogen deficient rats. Cell proliferation (WST1) and synthesis of alkaline phosphatase (ALP), osteocalcin (OC), collagen I (CICP), transforming growth factor beta1 (TGF-beta1), interleukin-6 (IL-6), tumor necrosis factor alfa (TNFalpha) were measured at 3, 7 and 14 days of culture. Osteoblast proliferation rate and TGF-beta1, IL-6 and TNFalpha syntheses were significantly affected by alcohol exposure. Estrogen deficiency and alcohol consumption share many common pathophysiological mechanisms of damage to bone, but alcohol affects OB proliferation and TNFalpha synthesis significantly more than menopause does. Therefore, these in vitro data suggest that alcohol has even more deleterious effects on bone than estrogen deficiency does.

BACKGROUND: A history of alcohol dependence recruits increased voluntary alcohol intake and sensitivity to stress. Corticotropin-releasing hormone (CRH) has been implicated in this transition, but underlying molecular mechanisms remain unclear. METHODS: A postdependent state was induced using intermittent alcohol exposure. Experiments were carried out following >/=3 weeks of recovery to eliminate contributions of acute withdrawal. Voluntary alcohol consumption was assessed in a two-bottle, free choice procedure. Behavioral sensitivity to stress was examined using fear suppression of behavior in a punished drinking (Vogel) conflict test. Effects of forced swim stress on voluntary alcohol intake were examined as a function of exposure history. Expression of Crh, Crhr1, and Crhr2 transcripts was analyzed by in situ hybridization histochemistry. RESULTS: Alcohol drinking was upregulated long-term following a history of dependence. Fear suppression of behavior was selectively potentiated in postdependent animals. This persisted 3 months after alcohol exposure and was reversed by the selective CRH-R1 antagonist 3-(4-Chloro-2-morpholin-4-yl-thiazol-5-yl)-8-(1-ethylpropyl)-2,6-dimethyl-imidazo [1,2-b]pyridazine (MTIP) (10 mg/kg). Forced swim stress increased alcohol intake in postdependent animals but not in control animals. Behavioral changes were paralleled by an upregulation of Crhr1 transcript expression within basolateral (BLA) and medial (MeA) amygdala and Crh messenger RNA (mRNA) in central amygdala (CeA). In contrast, Crhr2 expression was down in the BLA. CONCLUSIONS: Neuroadaptations encompassing amygdala CRH signaling contribute to the behavioral phenotype of postdependent animals.

The present study was performed to validate a spatial working memory task using pharmacological manipulations. The water escape T-maze combines the advantages of the Morris water maze and the T-maze while minimizing the disadvantages. Scopolamine (1mg/kg), a drug that affects cognitive function in spatial working memory tasks, significantly decreased the rats' performance in the present delayed alternation task. Glutamate neurotransmission plays an important role in the maintenance of working memory; rats treated with dizocilpine (MK-801; 0.125-0.25mg/kg), a N-methyl-d-aspartate (NMDA) receptor antagonist, were impaired in this task. In agreement with evidence showing a functional interaction between ionotropic and metabotropic glutamatergic receptors, 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a mGlu(5) receptor antagonist, at a dose (1mg/kg) which by itself had no significant effects, enhanced MK-801-induced impairments of spatial working memory. These evidences suggest that the water escape T-maze might be a valid method to assess spatial working memory, sensitive to pharmacological manipulations.

It is widely believed that the opiate system is involved in the development of alcoholism. Beta arrestin 2 (Arrb2) is a crucial modulator of this system; suggesting that Arrb2 is important for drug reward behaviors. In this study we further elucidated the putative role of Arrb2 in ethanol consumption. We fi rst compared Arrb2 brain expression levels between alcohol-preferring AA and nonpreferring ANA rats by in situ hybridization. We found differential expression levels in ventral and dorsal striatum, as well as hippocampus. Sequence analysis of Arrb2 showed a novel haplotype variant that completely discriminates between the lines. We then characterized the impact of this gene on ethanol related behaviors using Arrb2 null-mutant mice. Compared to wild type animals, Arrb2 mutant and heterozygote mice demonstrate reduced voluntary ethanol consumption and reduced ethanol induced locomotion. Mutant mice also show a decreased sensitivity to ethanol-induced sedation. Our data support a role for Arrb2 in mediating the rewarding effects of ethanol.

It is increasingly recognized that anti-reward systems are progressively recruited during the development of ethanol dependence, and may constitute a key component in maintaining the dependent phenotype. We recently demonstrated that in rodents, repeated cycles of ethanol intoxication and withdrawal for a prolonged period of time induces a phenotype of long-lasting increased ethanol drinking that models several facets of human alcoholism. Here, we found that elevated stress sensitivity parallels the high ethanol preference in this model, and contributes to the propensity to consume increased amounts of ethanol. After 7 weeks of daily cycles of intoxication and withdrawal rats were allowed to recover for 3 weeks without access to ethanol. In the first experiment we subjected rats to a punished drinking test (Vogel) w/o antagonist pretreatment with a corticotropin releasing hormone receptor 1 (CRH1R). Dependent rats showed a more pronounced behavioral suppression during the punished drinking period than controls. This suppression was alleviated by the CRH1R antagonist.exposed rats and controls were subjected to a 2-bottle freechoice, continuous access drinking paradigm. We then tested the effect of theantagonist on drinking behavior in a 2-bottle free choice, 1 hr-limited accessparadigm. No effect of the drug on ethanol consumption was found. In a second setof rats we asked whether the increased sensitivity to stress affects home cage drinking. As expected, previously exposed rats consumemarkedly higher amounts ofethanol than controls. Rats were than subjected for 3 consecutive days to sessions ofinescapable stress (forced swimming in cold water). During the week after thestressor rats with a history of dependence showed a sustained increase in drinkingfrom their previous base line, while control rats did not. A third group of animals wasanalyzed for CRH1R receptor expression and density. In conclusion, we provideevidence for an overactive CRH system in rats with a history of dependence causing hyper-emotionality and thereby contributing to relapse behavior.

It is increasingly recognized that anti-reward systems (i.e. negative reinforcement through stress and fear systems) are progressively recruited during the development of alcoholism, and may constitute a key component in maintaining the dependent phenotype. Extra-hypothalamic CRH (corticotrophin releasing hormone) signaling is thought to be of crucial importance in this process. However, understanding the impact of the CRH mediated neurotransmission in ethanol dependence and its potential value as a candidate target for treatment of ethanol use disorders requires modeling the neuroadaptations which occur with prolonged exposure of the brain to ethanol. To this end we have recently developed an animal model, which based on repeated cycles of intoxication and withdrawal, mimics the natural history of alcoholism and triggers long lasting plasticity. Methods: Male Wistar rats were exposed to either 4 or 7 weeks of daily cycles of ethanol vapor intoxication and withdrawal followed by 3 weeks of abstinence. Animals were then assigned to 3 separate experiments to investigate: 1) voluntary home cage ethanol consumption in a 2-bottle, free choice drinking paradigm; 2) fear-induced suppression of behavior in a punished drinking paradigm with or without pretreatment with a CRH receptor 1 antagonist; and 3) sacrificed for the study CRH and its receptors in the medial prefrontal cortex and the extended amygdala by in situ hybridization and receptor autoradiography. Results: Only 7-weeks exposed animals show signs of withdrawal at the end of the exposure cycle and consume significantly more ethanol after the 3 weeks resting period (p < 0.05, 7-weeks exposed vs. control). Associated with the drinking phenotype was an increased fear response in the conflict test (p < 0.01), increased expression of CRH in the central amygdala (p < 0.05) and its receptor CRH-R1 in central (p < 0.05), medial (p < 0.01) as well as basolateral amygdala (p < 0.001) in 7-weeks exposed animals compared to non-exposed controls. There was a trend to significant increased fear- suppression also in animals with a history of only 4 weeks cyclic intoxication and withdrawal, but no alterations in CRH signaling. Furthermore, heightened fear response was still visible fourteen weeks after the induction of the high-drinking phenotype and was completely abolished by a specific, highly brain-penetrant CRH-R1 antagonist. Discussion: Enhanced fear suppression seems to be an early onset and long-lasting phenotype in the development of ethanol dependence and is accompanied by long-term upregulation of CRH circuits in the amygdala. Together, these data support the hypothesis of an early recruitment of anti-reward systems in the descent into alcoholism and emphasize the potential of the CRH-R1 receptor as a treatment target for this disorder.

Evidence from genetically modified mice suggests a role for NPY in regulation of ethanol intake, but results of pharmacological studies have been more variable. We have previously shown that potentiation of NPY signaling through antagonism at NPY-Y2 receptors decreases operant responding for ethanol in Wistar rats without a history of dependence. Here, we examined the effects of Y2-antagonism in animals with a history of dependence induced by long-term intermittent exposure to ethanol vapor. The Y2-receptor antagonist BIIE0246 suppressed operant responding for ethanol (approximately 50%, p = 0.01), at a dose (0.5 nmol i.c.v.) which was ineffective in subjects without a history of dependence. Responding for the ethanol-free control solution was unaffected. These data confirm that antagonism at central NPY-Y2 receptors selectively suppresses motivation to self-administer ethanol, and indicate that the NPY system is sensitized in animals with a history of dependence. This may render the NPY system, and Y2 receptors in particular, an attractive target for treatment of alcohol dependence.

Chronic treatment with cannabinoid agonists leads to tolerance. One possible mechanism for this is receptor internalization, but tolerance has also been reported with compounds that only cause internalization to a low degree. Furthermore, cannabinoid antagonist administration precipitates a characteristic withdrawal syndrome in tolerant subjects, accompanied by neuronal activation and enhanced release of corticotropin-releasing hormone (CRH) in the central amygdala. The underlying molecular mechanisms are unknown. We examined the role of cannabinoid tolerance and withdrawal for the expression of the cannabinoid 1 (CB1) receptor and of CRH in rats. Tolerance was first established functionally. An acute dose (100 mug/kg) of the CB1 agonist HU-210 suppressed locomotor activity, and had an anxiogenic-like effect on the elevated plus-maze. Both effects were absent following daily treatment with the same agonist or a lower (40 mug/kg) dose for 14 days. Next, withdrawal was reliably precipitated by a single dose (3 mg/kg) of the CB1 antagonist SR141716A in rats treated subchronically with 14-day HU-210. Using in situ hybridization, a robust suppression of CB1 mRNA expression was found in the caudate-putamen, indicating a downregulation of CB1 expression levels as one mechanism for tolerance to the locomotor suppressant effects of HU-210. The CRH transcript was upregulated in the central amygdala in precipitated withdrawal compared to nonwithdrawn tolerant subjects, suggesting that increased gene expression contributes to the previously reported CRH release in withdrawal. Most importantly, this increase occurred from a suppressed level in tolerant subjects, and behavioral signs of withdrawal, presumably mediated by CRH, were seen at the CRH expression that had only returned to normal nontolerant levels. This suggests the possibility of an allostatic shift, as previously proposed on theoretical grounds. The expression of CRH-R1, CRH-R2a, NPY, and its Y1 receptor mRNA was analyzed in search of neural substrates for the allostatic shift observed, but did not seem to contribute to the dysregulated state.

In Alzheimer’s disease (AD) patients, apopoliprotein (APOE) polymorphism is the main genetic factor associated with more aggressive clinical course. However, the interaction between cerebrospinal fluid (CSF) tau protein levels and APOE genotype has been scarcely investigated. A possible key mechanism invokes the dysfunction of synaptic plasticity. We investigated how CSF tau interacts with APOE genotype in AD patients. We firstly explored whether CSF tau levels and APOE genotype influence disease progression and long-term potentiation (LTP)-like cortical plasticity as measured by transcranial magnetic stimulation (TMS) in AD patients. Then, we incubated normal human astrocytes (NHAs) with CSF collected from sub-groups of AD patients to determine whether APOE genotype and CSF biomarkers influence astrocytes survival. LTP-like cortical plasticity differed between AD patients with apolipoprotein E4 (APOE4) and apolipoprotein E3 (APOE3) genotype. Higher CSF tau levels were associated with more impaired LTP-like cortical plasticity and faster disease progression in AD patients with APOE4 but not APOE3 genotype. Apoptotic activity was higher when cells were incubated with CSF from AD patients with APOE4 and high tau levels. CSF tau is detrimental on cortical plasticity, disease progression and astrocyte survival only when associated with APOE4 genotype. This is relevant for new therapeutic approaches targeting tau.

Intellectual disability is the unavoidable hallmark of Down syndrome (DS), with a heavy impact on public health. Reduced neurogenesis and impaired neuron maturation are considered major determinants of altered brain function in DS. Since the DS brain starts at a disadvantage, attempts to rescue neurogenesis and neuron maturation should take place as soon as possible. The brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a key role in brain development by specifically binding to tropomyosin-related kinase receptor B (TrkB). Systemic BDNF administration is impracticable because BDNF has a poor blood-brain barrier penetration. Recent screening of a chemical library has identified a flavone derivative, 7,8-dihydroxyflavone (7,8-DHF), a small-molecule that crosses the blood-brain barrier and binds with high affinity and specificity to the TrkB receptor. The therapeutic potential of TrkB agonists for neurogenesis improvement in DS has never been examined. The goal of our study was to establish whether it is possible to restore brain development in the Ts65Dn mouse model of DS by targeting the TrkB receptor with 7,8-DHF. Ts65Dn mice subcutaneously injected with 7,8-DHF in the neonatal period P3-P15 exhibited a large increase in the number of neural precursor cells in the dentate gyrus and restoration of granule cell number, density of dendritic spines and levels of the presynaptic protein synaptophysin. In order to establish the functional outcome of treatment, mice were treated with 7,8-DHF from P3 to adolescence (P45-50) and were tested with the Morris Water Maze. Treated Ts65Dn mice exhibited improvement of learning and memory, indicating that the recovery of the hippocampal anatomy translated into a functional rescue. Our study in a mouse model of DS provides novel evidence that treatment with 7,8-DHF during the early postnatal period restores the major trisomy-linked neurodevelopmental defects, suggesting that therapy with 7,8-DHF may represent a possible breakthrough for Down syndrome.

Fabry disease is a X-linked lysosomal storage disorder caused by deficient function of the alpha-galactosidase A (α-GalA) enzyme. α-GalA deficiency leads to multisystemic clinical manifestations caused by the preferential accumulation of globotriaosylceramide (Gb3) in the endothelium and vascular smooth muscles. A hallmark symptom of Fabry disease patients is neuropathic pain that appears in the early stage of the disease as a result of peripheral small fiber damage. The α-GalA gene null mouse model (α-GalA(-/0)) has provided molecular evidence for the molecular alterations in small type-C nociceptors in Fabry disease that may underlie their hyperexcitability, although the specific mechanism remains elusive. Here, we have addressed this question and report that small type-C nociceptors from α-GalA(-/0) mice exhibit a significant increase in the expression and function of the TRPV1 channel, a thermoTRP channel implicated in painful heat sensation. Notably, male α-GalA(-/0) mice displayed a ≈2-fold higher heat sensitivity than wild-type animals, consistent with the augmented expression levels and activity of TRPV1 in α-GalA(-/0) nociceptors. Intriguingly, blockade of neuronal exocytosis with peptide DD04107, a process that inhibits among others the algesic membrane recruitment of TRPV1 channels in peptidergic nociceptors, virtually eliminated the enhanced heat nociception of α-GalA(-/0) mice. Together, these findings suggest that the augmented expression of TRPV1 in α-GalA(-/0) nociceptors may underly at least in part their increased heat sensitivity, and imply that blockade of peripheral neuronal exocytosis may be a valuable pharmacological strategy to reduce pain in Fabry disease patients, increasing their quality of life.