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Scientific interest in serotonergic psychedelics (e.g., psilocybin and LSD; 5-HT receptor agonists) has dramatically increased within the last decade. Clinical studies administering psychedelics with psychotherapy have shown preliminary evidence of robust efficacy in treating anxiety and depression, as well as addiction to tobacco and alcohol. Moreover, recent research has suggested that these compounds have potential efficacy against inflammatory diseases through novel mechanisms, with potential advantages over existing antiinflammatory agents. We propose that psychedelics exert therapeutic effects for psychiatric disorders by acutely destabilizing local brain network hubs and global network connectivity via amplification of neuronal avalanches, providing the occasion for brain network "resetting" after the acute effects have resolved. Antiinflammatory effects may hold promise for efficacy in treatment of inflammation-related nonpsychiatric as well as potentially for psychiatric disorders. Serotonergic psychedelics operate through unique mechanisms that show promising effects for a variety of intractable, debilitating, and lethal disorders, and should be rigorously researched.

Drosophila melanogaster, the fruit fly, has been used to study molecular mechanisms of a wide range of human diseases such as cancer, cardiovascular disease and various neurological diseases 1 . We have optimized simple and robust behavioral assays for determining larval locomotion, adult climbing ability (RING assay), and courtship behaviors of Drosophila. These behavioral assays are widely applicable for studying the role of genetic and environmental factors on fly behavior. Larval crawling ability can be reliably used for determining early stage changes in the crawling abilities of Drosophila larvae and also for examining effect of drugs or human disease genes (in transgenic flies) on their locomotion. The larval crawling assay becomes more applicable if expression or abolition of a gene causes lethality in pupal or adult stages, as these flies do not survive to adulthood where they otherwise could be assessed. This basic assay can also be used in conjunction with bright light or stress to examine additional behavioral responses in Drosophila larvae. Courtship behavior has been widely used to investigate genetic basis of sexual behavior, and can also be used to examine activity and coordination, as well as learning and memory. Drosophila courtship behavior involves the exchange of various sensory stimuli including visual, auditory, and chemosensory signals between males and females that lead to a complex series of well characterized motor behaviors culminating in successful copulation. Traditional adult climbing assays (negative geotaxis) are tedious, labor intensive, and time consuming, with significant variation between different trials [2][3][4] . The rapid iterative negative geotaxis (RING) assay 5 has many advantages over more widely employed protocols, providing a reproducible, sensitive, and high throughput approach to quantify adult locomotor and negative geotaxis behaviors. In the RING assay, several genotypes or drug treatments can be tested simultaneously using large number of animals, with the high-throughput approach making it more amenable for screening experiments. Video LinkThe 3. Incubate bottle for 3-4 days, or until third instar larvae are visible. 4. Add 50 -100 ml of 20% sucrose to the bottle with larvae and let sit for 20 minutes. Larvae will float to the top. 5. Collect larvae using a 25 ml serological pipette with the tip cut off, and place into a mesh basket. 6. Wash larvae in the mesh basket two times with deionized H 2 O. Larvae are now ready for the experiments. To treat larvae with drug1. Use a brush to transport the desired number of larvae to a 5 ml beaker containing a solution 5% sucrose + drug. 2. Let larvae feed for at least 15 minutes. 3. Pour drug-treated larvae into a mesh basket and rinse. They are now ready to use. Locomotor Assay (measuring total distance travelled or body wall contractions)1. Use a brush to transport individual larva to a: 1. 15 cm Petri dish containing 2% agarose (previously poured and allowed to harden) over graph paper with a 0.2 cm 2 grid.

Amyotrophic lateral sclerosis (ALS) is an uncommon neurodegenerative disease caused by degeneration of upper and lower motor neurons. Several genes, including SOD1, TDP-43, FUS, Ubiquilin 2, C9orf72 and Profilin 1, have been linked with the sporadic and familiar forms of ALS. FUS is a DNA/RNA-binding protein (RBP) that forms cytoplasmic inclusions in ALS and frontotemporal lobular degeneration (FTLD) patients' brains and spinal cords. However, it is unknown whether the RNA-binding ability of FUS is required for causing ALS pathogenesis. Here, we exploited a Drosophila model of ALS and neuronal cell lines to elucidate the role of the RNA-binding ability of FUS in regulating FUS-mediated toxicity, cytoplasmic mislocalization and incorporation into stress granules (SGs). To determine the role of the RNA-binding ability of FUS in ALS, we mutated FUS RNA-binding sites (F305L, F341L, F359L, F368L) and generated RNA-binding-incompetent FUS mutants with and without ALS-causing mutations (R518K or R521C). We found that mutating the aforementioned four phenylalanine (F) amino acids to leucines (L) (4F-L) eliminates FUS RNA binding. We observed that these RNA-binding mutations block neurodegenerative phenotypes seen in the fly brains, eyes and motor neurons compared with the expression of RNA-binding-competent FUS carrying ALS-causing mutations. Interestingly, RNA-binding-deficient FUS strongly localized to the nucleus of Drosophila motor neurons and mammalian neuronal cells, whereas FUS carrying ALS-linked mutations was distributed to the nucleus and cytoplasm. Importantly, we determined that incorporation of mutant FUS into the SG compartment is dependent on the RNA-binding ability of FUS. In summary, we demonstrate that the RNA-binding ability of FUS is essential for the neurodegenerative phenotype in vivo of mutant FUS (either through direct contact with RNA or through interactions with other RBPs).

Aggressive behavior is widespread throughout the animal kingdom, and is a complex social behavior influenced by both genetics and environment. Animals typically fight over resources that include food, territory, and sexual partners. Of all the neurotransmitters, serotonin has been the most implicated in modulating aggressive behaviors in mammalian systems. In the fruit fly, Drosophila melanogaster, the involvement of serotonin itself in aggressive behaviors has been recently established, however, the underlying mechanisms have largely remained elusive. Here we describe the influence of different serotonin receptor subtypes on aggressive behaviors in Drosophila. Drosophila express homologs of three mammalian serotonin receptors: the 5-HT 1A , 5-HT 2 , and 5-HT 7 receptors. Significantly, these receptors mediate important behaviors in mammalian systems ranging from feeding, aggression, and sleep, to cognition. To examine the role of the 5-HT 2 Dro receptor, we utilized the selective 5-HT 2 receptor agonist (R)-1-[2,5-dimethoxy-4-iodophenyl]-2-aminopropane (DOI), and the 5-HT 2 receptor antagonist, ketanserin. To examine the role of 5-HT 1A -like receptors we used the 5-HT 1A receptor agonist 8-hydroxy-2-dipropylaminotetralin hydrobromide (8-OH-DPAT), and the 5-HT 1A receptor antagonist WAY100635. We find that activation of 5-HT 2 receptors with (R)-DOI appears to decrease overall aggression, whereas activation of 5-HT 1A -like receptors with 8-OH-DPAT increases overall aggression. Furthermore, the different serotonin receptor circuitries appear to mediate different aspects of aggression: 5-HT 2 receptor manipulation primarily alters lunging and boxing, whereas 5-HT 1A -like receptor manipulation primarily affects wing threats and fencing. Elucidating the effects of serotonergic systems on aggression in the fly is a significant advancement not only in establishing the fly as a system to study aggression, but as a system relevant to elucidating molecular mechanisms underlying aggression in mammals, including humans. KeywordsAggression; neuropharmacology; 5-HT; DOI; 8-OH-DPAT The study of aggression in flies has a long history (Jacobs, 1960(Jacobs, , 1978; Drosophila exhibits aggressive behavior in the acquisition of food, territory, and mates, and these behaviors can differ among fly strains (Jacobs, 1960, Dow and Schilcher, 1975, Jacobs, 1978 Corresponding Author: Charles D. Nichols, Ph.D., Dept. of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St., New Orleans, LA 70112, (504) 568-2957, (504) 568-2361 (fax), cnich1@lsuhsc.edu. Section Editor: Dr. Geoffrey M. Schoenbaum Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process e...

The G protein-coupled serotonin 5-hydroxytryptamine (5-HT) 2A receptor is primarily recognized for its role in brain neurotransmission, where it mediates a wide variety of functions, including certain aspects of cognition. However, there is significant expression of this receptor in peripheral tissues, where its importance is largely unknown. We have now discovered that activation of 5-HT 2A receptors in primary aortic smooth muscle cells provides a previously unknown and extremely potent inhibition of tumor necrosis factor (TNF)-␣-mediated inflammation. 5-HT 2A receptor stimulation with the agonist (R)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [(R)-DOI] rapidly inhibits a variety of TNF-␣-mediated proinflammatory markers, including intracellular adhesion molecule 1 (ICAM-1), vascular adhesion molecule 1 (VCAM-1), and interleukin (IL)-6 gene expression, nitric-oxide synthase activity, and nuclear translocation of nuclear factor B, with IC 50 values of only 10 to 20 pM.It is significant that proinflammatory markers can also be inhibited by (R)-DOI hours after treatment with TNF-␣. With the exception of a few natural toxins, no current drugs or small molecule therapeutics demonstrate a comparable potency for any physiological effect. TNF-␣-mediated inflammatory pathways have been strongly implicated in a number of diseases, including atherosclerosis, rheumatoid arthritis, psoriasis, type II diabetes, depression, schizophrenia, and Alzheimer's disease. Our results indicate that activation of 5-HT 2A receptors represents a novel, and extraordinarily potent, potential therapeutic avenue for the treatment of disorders involving TNF-␣-mediated inflammation. Note that because (R)-DOI can significantly inhibit the effects of TNF-␣ many hours after the administration of TNF-␣, potential therapies could be aimed not only at preventing inflammation but also treating inflammatory injury that has already occurred or is ongoing.Serotonin, 5-hydroxytryptamine (5-HT), is a small monoamine molecule primarily known for its role as a neurotransmitter. Within the brain, it modulates a variety of behaviors including cognition, mood, aggression, mating, feeding, and sleep . These behaviors are mediated through interactions at seven different receptor families (5-HT 1-7 ) comprised of 14 distinct subtypes . Each of these are G protein-coupled receptors, with the exception of the 5-HT 3 receptor, which is a ligandgated ion channel. Of all the serotonin receptors, the 5-HT 2A receptor, which is known to primarily couple to the G␣q effector pathway (Roth et al., 1986), has been the one most closely linked to complex behaviors. There is a high level of expression within the frontal cortex, with significant localization to the apical dendrites of cortical pyramidal cells (Willins et al., 1997), and further expression at lower levels PKC, protein kinase C; Gö 6976, 5,6,7,pyrrolo [3,4-c]carbazole-12-propanenitrile; PMA, phorbol 12-myristate 13-acetate; F-22, fragment 6 -22; LA-SS-Az, (2ЈS,4ЈS)-(ϩ)-9,10-didehydro-6-methylergoli...

Serotonin (5-hydroxytryptamine, 5-HT) receptor agonists have recently emerged as promising new treatment options for a variety of disorders. The recent success of these agonists, also known as psychedelics, like psilocybin for the treatment of anxiety, depression, obsessive-compulsive disorder (OCD), and addiction, has ushered in a renaissance in the way these compounds are perceived in the medical community and populace at large. One emerging therapeutic area that holds significant promise is their use as anti-inflammatory agents. Activation of 5-HT receptors produces potent anti-inflammatory effects in animal models of human inflammatory disorders at sub-behavioural levels. This review discusses the role of the 5-HT receptor in the inflammatory response, as well as highlight studies using the 5-HT agonist (R)-2,5-dimethoxy-4-iodoamphetamine [(R)-DOI] to treat inflammation in cellular and animal models. It also examines potential mechanisms by which 5-HT agonists produce their therapeutic effects. Overall, psychedelics regulate inflammatory pathways via novel mechanisms, and may represent a new and exciting treatment strategy for several inflammatory disorders.