A major obstacle for developing new antidepressants has been limited knowledge of the structure and function of a central target, the serotonin transporter (SERT). Established SERT inhibitors (SSRIs) were docked to an in silico SERT model to identify likely binding pocket amino acid residues. When mutated singly, no one of five implicated residues was critical for high affinity in vitro binding of SSRIs or cocaine. The in silico SERT model was used in ligand virtual screening (VS) of a small molecule structural library. Selected VS "hit" compounds were procured and tested in vitro; encouragingly, two compounds with novel structural scaffolds bound SERT with modest affinity. The combination of computational modeling, site-directed mutagenesis and pharmacologic characterization can accelerate binding site elucidation and the search for novel lead compounds. Such compounds may be tailored for improved serotonin receptor selectivity and reduced affinity for extraneous targets, providing superior antidepressants with fewer adverse effects. / Mylan School of Pharmacy and the Graduate School of Pharmaceutical Sciences; / Pharmacology / MS; / Thesis;

No description available.

Depression and anxiety are two of the most common psychiatric disorders and leading causes of disability. Antidepressants and anxiolytics, though revolutionary, do not treat all those suffering from these diseases satisfactorily. Psychedelics are currently under investigation as remedies for several ailments, including depression and anxiety. One classical psychedelic, Ayahuasca, is a concoction of the plants Banisteriopsis caapi and Psychotria viridis and has historically been used by Amazonian natives for therapeutic and ritual purposes. The brew contains monoamine oxidase-A inhibitors (MAOI) and N,N-dimethyltryptamine (DMT), producing an altered state of consciousness characterized by visions and introspection. In this systematic review, I aimed to determine the antidepressant and anxiolytic effects of Ayahuasca. Sixteen articles out of 687 hits on electronic databases (Web of Science, Scopus, and PubMed) were finally included after closer examination. The studies range in quality and are performed on healthy volunteers and volunteers with self-reported depression or anxiety and patients suffering from treatment-resistant and major depression. Ayahuasca seems to be well tolerated and safe to administer and consistently produce antidepressant and anxiolytic effects in the studies. However, the description of the sometimes arbitrary results vary, and higher-quality research is needed before we can be certain of Ayahuasca as a remedy.

Depression is an extremely common, devastating psychiatric syndrome with profound effects on the structure of neurons and the proteins that they express. However, the pathophysiology of depression remains unclear despite decades of extensive research efforts, and this lack of understanding makes it difficult to develop effective treatments. It is extremely problematic that conventional antidepressant drugs do not work for many patients, and those that do respond require weeks to months of continuous treatment before adequate therapeutic improvement is achieved. Therefore, there is a clear unmet need to develop mechanistically novel antidepressant compounds that are well-tolerated, more effective, and faster acting. Subjecting rats to repeated-corticosterone (CORT; stress hormone analogous to cortisol for humans) injections produces a depressive-like phenotype that can be used to make inferences about the human condition and screen compounds for antidepressant properties. Our laboratory has previously found that stress downregulates hippocampal reelin in a similar manner to that seen in depression patients, and that drugs with antidepressant actions recover this deficit. This provided a rationale to administer reelin directly into the hippocampus, which rescued behavioral and neurochemical deficits, but intrahippocampal infusions are not clinically viable. Reelin is expressed in the periphery and blood as well as the brain, so the aims of the collection of studies described here are to evaluate the antidepressant-like properties of peripheral intravenous (i.v.) reelin. In the first experiment, the antidepressant-like effects of several dosages of reelin (3/5μg given every 5/10 days) were evaluated in rats that were exposed to 3-weeks of daily CORT (40mg/kg) injections. I found that all the dosages of reelin attenuated CORT-induced despair-like behavior in the forced-swim test (FST) and normalized alterations in serotonin (5-HT) transporter (SERT) membrane protein clustering (MPC) in blood lymphocytes. Reelin treatment also increased reelin-immunoreactive (IR) cell counts in the hippocampal dentate gyrus (DG) subgranular zone (SGZ), but it had less of an effect on neurogenesis as measured by the number and maturation rate of doublecortin (DCX)-IR cells. Interestingly, the lowest dosage used also rescued the number of reelin-IR cells in the hypothalamic paraventricular nucleus (PVN). This suggested that the restoration of SGZ-reelin plays a pivotal role in attenuating depressive-like behavior and that 3μg every 10 days was the most effective dosage that was tested. Using the lowest dosage that showed to be effective in the first experiment, I then evaluated if male and female rats responded similarly to i.v. reelin using a larger battery of behavioral tests. Post-mortem tissue analyses focused on reelin and receptors that bind gamma-aminobutyric acid (GABA) and glutamate in the SGZ, which have been implicated in psychiatric disorders and the mediation of fast-acting antidepressant responses. I found that reelin rescued the FST- behavioral and neurochemical alterations induced by CORT similarly in both sexes, indicating that it may have therapeutic effects by normalizing inhibitory/excitatory transmission. I also evaluated the effect of i.v. reelin on neurogenesis in females and found that, akin to males, the regulation of adult-born cells by peripheral reelin is unlikely to mediate the antidepressant-like effects. The goal of the third experiment was to examine whether the antidepressant-like effects of peripheral reelin are achieved in a rapid manner. I found that a single 3μg injection after 3 weeks of CORT significantly decreased behavioral deficits in the FST 24 hours later in both sexes. Reelin also partially rescued cognitive deficits and expression levels of reelin, GluN2B, and mitochondrial-related pro-apoptotic factors bcl-2 associated X protein (BAX) and cytochrome C (CytC) in the DG. In addition, a single injection of reelin fully recovered the number of GluA1-expressing cells and partially recovered SERT cluster size in males, whereas reelin partially recovered GluA1-IR cell counts and fully recovered SERT cluster sizes in females. Reelin had modest effects on DCX-IR cells in both sexes. The final chapter summarizes and discusses my findings, which suggest that the antidepressant-like effects of peripheral reelin are associated with the recovery of neurochemical deficits that strengthen neurotransmission, at least in the hippocampus. Therefore, developing reelin-based therapeutics with antidepressant activity would be a fruitful area of research, although additional mechanistic, pharmacokinetic, and pharmacodynamic studies are essential. / Graduate

Neuropathic pain is a common problem in clinical practice, affecting patients physically, emotionally, financially, and socially. Current treatment includes antidepressants, antiepileptics, and opioid analgesics. Bupropion is a specific inhibitor of neuronal noradrenaline reuptake and a weak inhibitor of dopamine reuptake, which shows some promise in the treatment of neuropathic pain.

Depression has been associated with a low-grade chronic inflammatory state, suggesting a potential therapeutic role for anti-inflammatory agents. Fisetin is a naturally occurring flavonoid in strawberries that has anti-inflammatory activities, but whether fisetin has antidepressant effects is unknown. In this study, we exposed mice to spatial restraint for 2 weeks with or without treatment with fisetin. Immobility time in the forced swimming and tail suspension test after this restraint increased in the untreated group, but this increase did not occur in the fisetin group. We administered fisetin to Abelson helper integration site-1 (Ahi1) knockout mice, which have depressive phenotypes. We found that fisetin attenuated the depressive phenotype of these Ahi1 knockout mice. We further investigated the potential mechanism of fisetin's antidepressant effects. Because TrkB is a critical signaling pathway in the mechanisms of depression, we examined whether phosphorylated TrkB was involved in the antidepressant effects of fisetin. We found that fisetin increased phosphorylated TrkB level without altering total TrkB; this increase was attenuated by K252a, a specific TrkB inhibitor. Taken together, our results demonstrated that fisetin may have therapeutic potential for treating depression and that this antidepressant effect may be mediated by the activation of the TrkB signaling pathway. (Figure presented.).

Tricyclic antidepressants have been shown to alter thyroid function in man and laboratory animals, but have not been evaluated in the dog. The effect of administration of clomipramine on canine thyroid function was studied in a prospective protocol in which 14 mature, healthy dogs were administered clomipramine (3 mg/kg PO q12h) for 112 days. Thyroid-stimulating hormone (TSH), total thyroxine (T4), total 3,5,3' triiodothyronine (T3), free thyroxine (fT4), and 3,3',5' triiodothyronine (reverse T3; rT3) concentrations were measured on selected days. Thyrotropin-releasing hormone (TRH) response tests were performed concurrently. Repeated measures analysis of variance was applied to test for effects of day of treatment; when significance (p < 0.05) was noted, it was further investigated using orthogonal polynomial trends. Significant decreases were found in serum T4 (26 ± 1.2 to 17 ± 0.5 nmol/L, p < 0.001), fT4, (29 ± 2.4 to 19 ± 1.3 pmol/L, p < 0.0002), and rT3 (1.2 ± 0.1 to 0.83 ± 0.08 nmol/L, p < 0.0001) concentrations. The effect of time on serum T3 concentration was also significant (p < 0.0001), but no consistent trend could be identified. No significant effect of time was noted in either pre- or post-TRH TSH concentrations. The results of this study indicate that significant and substantial decreases in T4 (35%), fT4 (38%), and rT3 can occur during clomipramine administration. Long-term administration of clomipramine may result in a misdiagnosis of hypothyroidism if a dog is tested while taking this medication and, since decreased serum fT4 occurs, hypothyroidism may result. / Master of Science

Antidepressants are associated with sexual side effects (Clayton, Keller, & McGarvey, 2006). Sexual side effects are associated with non-compliance or discontinuance of antidepressants (Werneke, Northey, & Bhugra, 2006). Despite this, there are few empirically supported treatments for antidepressant side effects. However, in laboratory studies, exercise immediately before sexual stimuli improved sexual arousal of women taking antidepressants (Lorenz & Meston, 2012). I evaluated if exercise improves sexual functioning in women experiencing antidepressant-induced sexual side effects. Fifty-two women reporting antidepressant sexual side effects were followed for 3 weeks of sexual activity only. They were randomized to complete either three weeks of exercise immediately before sexual activity (3x/week) or 3 weeks of exercise separate from sexual activity (3x/week). At the end of the first exercise arm, participants crossed to the other. I measured sexual functioning, sexual satisfaction, depression and physical health. Completers showed modest improvements in sexual functioning and satisfaction. For women taking selective serotonin and norepinephrine reuptake inhibitors, exercising immediately before sexual activity was superior to exercise in general. As well as known effects in improved physical and psychological health, exercise may help improve sexual health and pleasure in women taking antidepressants. These findings have important implications for public health, as exercise is accessible, cheap, and does not add to burden of care. / text

Background: Mindfulness-based cognitive therapy (MBCT) is a promising new alternative to anti-depressant medication (Kuyken et al., 2015) and whilst some qualitative studies have explored participants' experiences of MBCT, none yet have explored experiences of participants who are considering coming off their antidepressant medication alongside MBCT or how patients experience change in relationships with self, others and illness. Aim: To examine MBCT participants' experience of change across 24 months, particularly in relation to change in views of their self and their illness over time. Method: Thematic analysis of in-depth retrospective interviews with 42 participants, two years after attending an 8 week MBCT group with an invitation to taper their antidepressant medication (ADM). Each participant took part in one retrospective interview which was semi-structured and focused on experiences of MBCT and ADM over the previous two years since attending an MBCT group and how these have impacted on a change in self and experience of illness. Findings and conclusion: Four over-arching themes were found: taking control, relationships (with self, other and illness), rebuilding the self and shifts in perspective. The findings in the current study are very similar to those found in transformation in the physical chronic illness literature (e.g. Paterson et al., 1999). Perhaps MBCT could be the challenge which lead patients suffering from chronic depression towards change and creates a context in which patients can consider self and identity.

Major depressive disorder (MDD) is a growing health problem. Current treatment options are not always effective and take several weeks of regular administration before an improvement can be seen in symptoms. Sub-anaesthetic doses of ketamine have been found to have antidepressant effects in previously treatment-resistant MDD after just one dose. However, ketamine also produces short term psychosis-like side effects which are undesirable for MDD patients. Ketamine is known to be an NMDA receptor antagonist, binding within the channel pore to block ion flow, however the molecular mechanism(s) underlying its antidepressant and psychosis-like effects are still unclear. In this thesis several genetically modified mouse lines were used to probe the molecular events involved in ketamine's actions. Firstly, a mouse line in which the c-terminal domain (CTD) of the NMDAR subtype GluN2B had been replaced with that of GluN2A, and a second line in which the opposite replacement had taken place, were used to investigate the role of the CTD in the NMDAR response to ketamine. It was found that the GluN2B CTD is required for the short-term psychosis-like response to a sub-anaesthetic dose of ketamine. This is interesting as the channel pore region, containing the binding site for ketamine, is unaltered in these mutants. Therefore, this finding implicates GluN2B CTD specific intracellular signalling molecules in this action of ketamine and raises the question of whether the CTD itself is able to respond to ketamine binding within the pore to induce signalling changes, perhaps via a conformational change. Secondly, a mouse line, in which the activity-regulated synaptic protein Arc has been tagged with a fluorescent marker, was used to investigate the response of synapses to both anaesthetic and sub-anaesthetic doses of ketamine. In this experiment tagged Arc protein was visible as punctate accumulations at synapses. A novel method termed 'synaptome mapping' was used to image these accumulations across entire coronal sections and to quantify their number, size and intensity. Using this method alterations to the Arc synaptome map were detected 1h, 6h and 24h following ketamine administration. The two doses used produced different changes to this map, with the sub-anaesthetic antidepressant dose inducing increases in Arc puncta number across many brain regions, whereas the anaesthetic dose induced short term (1h) increases followed by longer term decreases in Arc puncta number. This finding links long-term increases in Arc at the synapse with an antidepressant response to ketamine.