The Kappa Opioid Receptor Agonist 16-Bromo Salvinorin A Has Anti-Cocaine Effects without Significant Effects on Locomotion, Food Reward, Learning and Memory, or Anxiety and Depressive-like Behaviors.

Kappa opioid receptor (KOR) agonists have preclinical antipsychostimulant effects; however, adverse side effects have limited their therapeutic development. In this preclinical study, conducted in Sprague Dawley rats, B6-SJL mice, and non-human primates (NHPs), we evaluated the G-protein-biased analogue of salvinorin A (SalA), 16-bromo salvinorin A (16-BrSalA), for its anticocaine effects, side effects, and activation of cellular signaling pathways. 16-BrSalA dose-dependently decreased the cocaine-primed reinstatement of drug-seeking behavior in a KOR-dependent manner. It also decreased cocaine-induced hyperactivity, but had no effect on responding for cocaine on a progressive ratio schedule. Compared to SalA, 16-BrSalA had an improved side effect profile, with no significant effects in the elevated plus maze, light-dark test, forced swim test, sucrose self-administration, or novel object recognition; however, it did exhibit conditioned aversive effects. 16-BrSalA increased dopamine transporter (DAT) activity in HEK-293 cells coexpressing DAT and KOR, as well as in rat nucleus accumbens and dorsal striatal tissue. 16-BrSalA also increased the early phase activation of extracellular-signal-regulated kinases 1 and 2, as well as p38 in a KOR-dependent manner. In NHPs, 16-BrSalA caused dose-dependent increases in the neuroendocrine biomarker prolactin, similar to other KOR agonists, at doses without robust sedative effects. These findings highlight that G-protein-biased structural analogues of SalA can have improved pharmacokinetic profiles and fewer side effects while maintaining their anticocaine effects.

Infection and persistence of erythrovirus B19 in benign and cancerous thyroid tissues.

Human erythrovirus B19 (EVB19) is a small, pathogenic DNA virus that has been associated with a wide range of illnesses. The primary site of replication is in bone marrow-derived erythroid progenitor cells, but EVB19 DNA has been detected in a wide range of organs. Recently, studies have linked EVB19 to thyroid cancers and other thyroid diseases. Previous studies from multiple laboratories have detected EVB19 capsid proteins in Graves' disease, Hashimoto's thyroiditis, and thyroid cancer tissues. Data on viral gene expression and mechanism of infection in the thyroid are lacking. To investigate EVB19 infection and persistence in the thyroid, previously archived adult and pediatric tissue sections were examined for EVB19 DNA, RNA, and capsid proteins, as well as EVB19 receptor P-antigen and co-receptor α5ß1 integrin. EVB19 DNA and protein were detected in a majority of tissues examined (87% and 68%, respectively). Detection was similar in adult and pediatric samples. Quantification of viral genomes revealed no significant difference in the amount of viral DNA in benign, cancerous, or metastatic thyroid tissues. EVB19 capsid RNA was detected in 67% of the tissues examined, confirming at least low-level viral gene expression. Immunohistochemical staining for P-antigen and α5ß1 detected the receptor and co-receptor most frequently on normal thyroid epithelial cells. EVB19 capsid staining could be detected in tumors lacking viral receptors. These results suggest that normal thyroid epithelial cells are the initial target for EVB19 infection in the thyroid and allow for continued persistence in both normal and cancerous thyroid tissues.

Screen Failures in Clinical Trials in Retina.

PURPOSE: Disparities in clinical trials are a major problem because of significant underrepresentation of certain gender, racial, and ethnic groups. Several factors including stringent eligibility criteria and recruitment strategies hinder our understanding of retinal disease. Thus, we aimed to study the various reasons of screen failures and specific patient and study characteristics among screen failures. DESIGN: This is a cross-sectional retrospective study. METHODS: Screening data of 87 trials from 6 centers were analyzed. Study characteristics (disease studied, phase of trial, and route of drug administration) and patient demographics (age, gender, race, ethnicity, and employment status) were compared among different causes of screen failures. Screen failures were broadly classified into 6 categories: exclusion because of vision-based criteria, exclusion because of imaging findings, exclusion because of other factors, patient-related criteria, physician-related criteria, and miscellaneous. Descriptive statistics, Pearson chi-square test, and analysis of variance were used for statistical analysis. MAIN OUTCOME MEASURES: Prevalence of various reasons for screen failures in multiple trials and its trend among different study and patient characteristics. RESULTS: Among 87 trials and 962 patients, 465 (48.2%) patients were successfully randomized and 497 (51.8%) patients were classified as screen failures. The trials were conducted for various retinal diseases. Mean age was 76.50 ±10.45 years and 59.4% were females. Predominantly White patients (93.4%) and unemployed/retired patients (66.6%) were screened. Of the 497 screen failures, most were because of patients not meeting inclusion criteria of imaging findings (n = 221 [44.5%]) followed by inclusion of vision-based criteria (n = 73 [14.7%]), exclusion because of other factors (n = 75 [15.1%]), patient-related (n = 34 [6.8%]), physician-related (n = 28 [5.6%]), and miscellaneous reasons (n = 39 [7.8%]). Reason for screen failure was not available for 27 (5.4%) patients. A higher proportion of patients screened for surgical trials (15%) declined to participate in the study compared with noninvasive trials involving topical drugs and photobiomodulation (0%) (P = 0.02). CONCLUSIONS: Patients not meeting the imaging and vision-cased criteria were the most common reasons for screen failures. White patients and unemployed patients predominantly participated in clinical trials. Patients are more inclined to continue participation in noninvasive clinical trials compared with surgical trials. Better recruitment strategies and careful consideration of study criteria can aid in decreasing the rate of screen failures.

Quantifying burden of intravitreal injections: questionnaire assessment of life impact of treatment by intravitreal injections (QUALITII).

AIM: To quantify the areas of burden experienced by patients requiring repeated intravitreal injections (IVI) in the management of exudative retinal diseases. METHODS: The validated Questionnaire to Assess Life Impact of Treatment by Intravitreal Injections survey was administered to patients at four retina clinical practices across four US states. The primary outcome measure was Treatment Burden Score (TBS), a single score assessing overall burden. RESULTS: Of 1416 (n=657 age-related macular degeneration; n=360 diabetic macular oedema/diabetic retinopathy; n=221 retinal vein occlusion; n=178 other/uncertain) patients, 55% were women with an average age of 70 years. Patients most frequently reported receiving IVI every 4-5 weeks (40%). The mean TBS was 16.1±9.2 (range 1-48; scale of 1-54), and the TBS was higher in patients with diabetic macular oedema and/or diabetic retinopathy (DMO/DR) (17.1) compared with those with age-related macular degeneration (15.5) or retinal venous occlusive (15.3) (p=0.028). Though the mean level of discomfort was quite low (1.86) (scale 0-6), 50% of patients reported experiencing side effects more than half of the visits. Patients having received fewer than 5 IVI reported higher mean anxiety levels before (p=0.026), during (p=0.050) and after (p=0.016) treatment compared with patients having received more than 50 IVI. After the procedure, 42% of patients reported restrictions from usual activities due to discomfort. Patients reported a high mean satisfaction rating of 5.46 (scale 0-6) with the care of their diseases. CONCLUSIONS: The mean TBS was moderate and highest among patients with DMO/DR. Patients with more total injections reported lower levels of discomfort and anxiety but higher disruption to daily life. Despite the challenges related to IVI, the overall satisfaction with treatment remained high.

The C-2 derivatives of salvinorin A, ethoxymethyl ether Sal B and ß-tetrahydropyran Sal B, have anti-cocaine properties with minimal side effects.

RATIONALE: Kappa-opioid receptor (KOPr) agonists have pre-clinical anti-cocaine and analgesic effects. However, side effects including sedation, dysphoria, aversion, anxiety and depression limit their therapeutic development. The unique structure of salvinorin A has been used to develop longer acting KOPr agonists. OBJECTIVES: We evaluate two novel C-2 analogues of salvinorin A, ethoxymethyl ether Sal B (EOM Sal B) and ß-tetrahydropyran Sal B (ß-THP Sal B) alongside U50,488 for their ability to modulate cocaine-induced behaviours and side effects, pre-clinically. METHODS: Anti-cocaine properties of EOM Sal B were evaluated using the reinstatement model of drug seeking in self-administering rats. EOM Sal B and ß-THP Sal B were evaluated for effects on cocaine-induced hyperactivity, spontaneous locomotor activity and sucrose self-administration. EOM Sal B and ß-THP Sal B were evaluated for aversive, anxiogenic and depressive-like effects using conditioned place aversion (CPA), elevated plus maze (EPM) and forced swim tests (FSTs), respectively. RESULTS: EOM Sal B (0.1, 0.3 mg/kg, intraperitoneally (i.p.)) dose dependently attenuated drug seeking, and EOM Sal B (0.1 mg/kg, i.p.) and ß-THP Sal B (1 mg/kg, i.p.) attenuated cocaine-induced hyperactivity. No effects on locomotor activity, open arm times (EPM) or swimming behaviours (FST) were seen with EOM (0.1 or 0.3 mg/kg, i.p.) or ß-THP Sal B (1 or 2 mg/kg, i.p.). However, ß-THP Sal B decreased time spent in the drug-paired chamber. CONCLUSION: EOM Sal B is more potent than Sal A and ß-THP Sal B in reducing drug-seeking behaviour with fewer side effects. EOM Sal B showed no effects on sucrose self-administration (0.1 mg/kg), locomotor, depressive-like, aversive-like or anxiolytic effects.

Salvinorin A analogs and other κ-opioid receptor compounds as treatments for cocaine abuse.

Acute activation of kappa-opioid receptors produces anti-addictive effects by regulating dopamine levels in the brain. Unfortunately, classic kappa-opioid agonists have undesired side effects such as sedation, aversion, and depression, which restrict their clinical use. Salvinorin A (Sal A), a novel kappa-opioid receptor agonist extracted from the plant Salvia divinorum, has been identified as a potential therapy for drug abuse and addiction. Here, we review the preclinical effects of Sal A in comparison with traditional kappa-opioid agonists and several new analogs. Sal A retains the anti-addictive properties of traditional kappa-opioid receptor agonists with several improvements including reduced side effects. However, the rapid metabolism of Sal A makes it undesirable for clinical development. In an effort to improve the pharmacokinetics and tolerability of this compound, kappa-opioid receptor agonists based on the structure of Sal A have been synthesized. While work in this field is still in progress, several analogs with improved pharmacokinetic profiles have been shown to have anti-addictive effects. While in its infancy, it is clear that these compounds hold promise for the future development of anti-addictive therapeutics.

Synthesis and κ-opioid receptor activity of furan-substituted salvinorin A analogues.

The neoclerodane diterpene salvinorin A, found in the leaves of Salvia divinorum, is a potent κ-opioid receptor agonist, making it an attractive scaffold for development into a treatment for substance abuse. Although several successful semisynthetic studies have been performed to elucidate structure-activity relationships, the lack of analogues with substitutions to the furan ring of salvinorin A has prevented a thorough understanding of its role in binding to the κ-opioid receptor. Herein we report the synthesis of several salvinorin A derivatives with modified furan rings. Evaluation of these compounds in a functional assay indicated that sterically less demanding substitutions are preferred, suggesting the furan ring is bound in a congested portion of the binding pocket. The most potent of the analogues successfully reduced drug-seeking behavior in an animal model of drug-relapse without producing the sedation observed with other κ-opioid agonists.

Salvinorin A regulates dopamine transporter function via a kappa opioid receptor and ERK1/2-dependent mechanism.

Salvinorin A (SalA), a selective κ-opioid receptor (KOR) agonist, produces dysphoria and pro-depressant like effects. These actions have been attributed to inhibition of striatal dopamine release. The dopamine transporter (DAT) regulates dopamine transmission via uptake of released neurotransmitter. KORs are apposed to DAT in dopamine nerve terminals suggesting an additional target by which SalA modulates dopamine transmission. SalA produced a concentration-dependent, nor-binaltorphimine (BNI)- and pertussis toxin-sensitive increase of ASP(+) accumulation in EM4 cells coexpressing myc-KOR and YFP-DAT, using live cell imaging and the fluorescent monoamine transporter substrate, trans 4-(4-(dimethylamino)-styryl)-N-methylpyridinium) (ASP(+)). Other KOR agonists also increased DAT activity that was abolished by BNI pretreatment. While SalA increased DAT activity, SalA treatment decreased serotonin transporter (SERT) activity and had no effect on norepinephrine transporter (NET) activity. In striatum, SalA increased the Vmax for DAT mediated DA transport and DAT surface expression. SalA up-regulation of DAT function is mediated by KOR activation and the KOR-linked extracellular signal regulated kinase-½ (ERK1/2) pathway. Co-immunoprecipitation and BRET studies revealed that DAT and KOR exist in a complex. In live cells, DAT and KOR exhibited robust FRET signals under basal conditions. SalA exposure caused a rapid and significant increase of the FRET signal. This suggests that the formation of KOR and DAT complexes is promoted in response to KOR activation. Together, these data suggest that enhanced DA transport and decreased DA release resulting in decreased dopamine signalling may contribute to the dysphoric and pro-depressant like effects of SalA and other KOR agonists.

The 2-methoxy methyl analogue of salvinorin A attenuates cocaine-induced drug seeking and sucrose reinforcements in rats.

κ Opioid receptor activation by traditional arylacetamide agonists and the novel neoclerodane diterpene κ opioid receptor agonist Salvinorin A (Sal A) results in attenuation of cocaine-seeking behavior in pre-clinical models of addiction. However, adverse effects such as sedation, depression and aversion limit their clinical utility. The Sal A analogue, 2-methoxy-methyl salvinorin B (MOM Sal B) is a longer acting Sal A analogue with high affinity for κ opioid receptors. In this study, we tested MOM Sal B for its ability to modulate cocaine-seeking behavior in rats. MOM Sal B (0.3mg/kg) successfully attenuated cocaine-seeking but also attenuated sucrose reinforcement. No change in activity was observed in either cocaine-induced hyperactivity or spontaneous open field activity tests but increased immobility and decreased swimming times in the forced swim test were observed. This study indicates that κ opioid receptor activation by more potent Sal A analogues modulates cocaine-seeking behavior non-selectively without causing sedation, suggesting an improved side effects profile. However, pro-depressive effects are seen, which may limit the therapeutic potential of this compound. Future studies with Sal A analogues having affinities at other opioid receptors are warranted as they have the potential to identify compounds having effective anti-addiction properties.