Diverse therapeutic developments for post-traumatic stress disorder (PTSD) indicate common mechanisms of memory modulation.

Post-traumatic stress disorder (PTSD), characterized by abnormally persistent and distressing memories, is a chronic debilitating condition in need of new treatment options. Current treatment guidelines recommend psychotherapy as first line management with only two drugs, sertraline and paroxetine, approved by U.S. Food and Drug Administration (FDA) for treatment of PTSD. These drugs have limited efficacy as they only reduce symptoms related to depression and anxiety without producing permanent remission. PTSD remains a significant public health problem with high morbidity and mortality requiring major advances in therapeutics. Early evidence has emerged for the beneficial effects of psychedelics particularly in combination with psychotherapy for management of PTSD, including psilocybin, MDMA, LSD, cannabinoids, ayahuasca and ketamine. MDMA and psilocybin reduce barrier to therapy by increasing trust between therapist and patient, thus allowing for modification of trauma related memories. Furthermore, research into the memory reconsolidation mechanisms has allowed for identification of various pharmacological targets to disrupt abnormally persistent memories. A number of pre-clinical and clinical studies have investigated novel and re-purposed pharmacological agents to disrupt fear memory in PTSD. Novel therapeutic approaches like neuropeptide Y, oxytocin, cannabinoids and neuroactive steroids have also shown potential for PTSD treatment. Here, we focus on the role of fear memory in the pathophysiology of PTSD and propose that many of these new therapeutic strategies produce benefits through the effect on fear memory. Evaluation of recent research findings suggests that while a number of drugs have shown promising results in preclinical studies and pilot clinical trials, the evidence from large scale clinical trials would be needed for these drugs to be incorporated in clinical practice.

Effects of propranolol on the modification of trauma memory reconsolidation in PTSD patients: A systematic review and meta-analysis.

Post-traumatic stress disorder (PTSD) develops after an exposure to a life-threatening event and is characterized by intrusive memories. According to memory reconsolidation theory retrieval of memory under certain conditions leads to its labilization and subsequent re-storage which could be disrupted by drugs. Propranolol has been the most commonly investigated drug for memory reconsolidation therapy in clinical trials. Intervention with propranolol have shown mixed results in PTSD patients with some studies showing improvement in symptoms while other failing to replicate these findings. We conducted a systematic review and meta-analysis to determine the efficacy of trauma memory disruption by propranolol on PTSD symptoms and physiological responses in PTSD patients. 3224 publications were assessed for eligibility. Seven studies on effects of propranolol on PTSD symptoms and 3 studies on effects of propranolol on physiological responses were incorporated in the meta-analyses. Overall, results indicate that propranolol did not show a beneficial effect on PTSD symptoms (standardized mean difference: 1.29; 95% CI = -2.16 - 0.17). Similarly, propranolol did not influence skin conductance (standardized mean difference: 0.77; 95% CI = -1.85 - 0.31) or EMG response (standardized mean difference: 0.16; 95% CI = -0.65 - 0.33). However, propranolol significantly reduced heart rate after trauma memory recall compared to placebo (standardized mean difference: 0.67; 95% CI = -1.27 to -0.07). This study finds a lack of evidence for the efficacy of propranolol on traumatic memory disruption, in PTSD patients, to recommend its routine clinical use. However, a high level of heterogeneity, variation in propranolol dosage and inadequate sample sizes mean that these findings require cautious interpretation.

Effect of Jyotismati seed oil on spatial and fear memory using scopolamine induced amnesia in mice.

BACKGROUND: Treatment of memory impairment associated with dementia such as Alzheimer's disease is still inadequate and requires development of new drugs. OBJECTIVE: The objective was to evaluate the memory enhancing effect of Celastrus paniculatus seed oil. MATERIALS AND METHODS: C. paniculatus seed oil was mixed with equal amount of pure ghee and administered orally to mice in the dose of 200 mg/kg/day. Piracetam was used as a standard nootropic. Elevated plus maze and passive avoidance tests were used as a models to test spatial and fear memory respectively. Scopolamine (3 mg/kg, i.p.), was used as an amnestic agent. RESULTS: Mice receiving C. paniculatus showed significant memory enhancement as compared to scopolamine group. The effect of C. paniculatus and combination of C. paniculatus with piracetam was comparable to that with piracetam alone. CONCLUSION: The present study demonstrates that C. paniculatus seed oil has memory enhancing effect and hence can be developed as a potential drug in the treatment of dementia.

Evaluation of the estrogenic activity of Indian medicinal plants in immature rats.

INTRODUCTION: The objective of the study was to evaluate the estrogenic activity of four Indian medicinal plants Saraca indica (Si), Symplocos racemosa (Sr), Cyperus rotundus (Cr), Terminalia arjuna (Ta), a marketed preparation of Si (Asokarista) and a combination of Si + Sr using an experimental model of estrogenicity. MATERIALS AND METHODS: After approval of the institutional animal ethics committee, 22 day old female rats (n = 54) were randomly allocated to 9 groups - Group 1 and Group 2: Vehicle controls, Group 3: Ethinyl estradiol, Group 4: Si (270 mg/kg), Group 5: Sr (270 mg/kg), Group 6: Cr (540 mg/kg), Group 7: Ta (270 mg/kg), Group 8: Ashokarishta (4 ml/kg), Group 9: Si + Sr (135 mg/kg). Variables studied were: Body weight, uterine weight, relative uterine weight, presence of vaginal opening, histomorphology of the uterus and total uterine glycogen content. Parametric data were analyzed using one-way ANOVA and the categorical data were analyzed using Chi-square test. RESULTS: All animals in the ethinyl estradiol group showed a significant change in all the variables. None of the individual test drugs, neither the marketed preparation produced change in any of the variables. The plant drug combination also did not produce a change in any of the variables studied except in histomorphology wherein it caused a slight increase in the height of the luminal epithelium of the uterus (P < 0.05 vs. Group 1). CONCLUSION: The plant drugs Si, Sr, Cr, Ta and Asokarista did not demonstrate estrogenic activity in the immature rat model. The plant drug combination Si + Sr showed questionable estrogenic activity which needs to be evaluated in further studies.

Role of dopamine--D2 receptor in spatial memory retention and retrieval determined using Hebb-Williams complex maze.

Effects of bromocriptine and sulpiride were observed on encoding and retrieval of spatial memory in Wistar rats using Hebb-Williams complex maze. Rat was placed in entry chamber and allowed to reach reward chamber. Ten trials were given each day per rat for 3 consecutive days. Within-day encoding score indicative of learning and between-day retrieval score indicative of memory were calculated. Effects of bromocriptine and sulpiride were observed on encoding and retrieval of spatial memory. General learning index was calculated to compare the effect on spatial memory between groups. Bromocriptine increased while sulpiride decreased within-day encoding index but had no effect on retrieval index. In general learning index, sulpiride group showed more errors whereas bromocriptine group did not show any difference as compared to control. These results suggest that dopamine D2 receptors are involved in memory encoding but not retrieval. Also general learning is under positive modulation by D2 receptors.

Effect of combination of Phyllanthus emblica, Tinospora cordifolia, and Ocimum sanctum on spatial learning and memory in rats.

BACKGROUND: There has been a steady rise in number of patients suffering from dementia including dementia associated with Alzheimer's disease. Effective treatment of Alzheimer's disease dementia is an unmet medical need. OBJECTIVE: To evaluate effects of formulation containing combination of Phyllanthus emblica (Pe) and Tinospora cordifolia (Tc) with and without Ocimum sanctum (Os) on learning and memory performance of normal and memory impaired rats in complex maze and compare with effects of Tinospora cordifolia and Phyllanthus emblica alone. MATERIALS AND METHODS: Wistar rats; either sex (100-150 g) were divided in seven groups Control, Piracetam, Rivastigmine, Tc, Pe, Formulation 1 (Tc + Pe), and Formulation 2 (Tc + Pe + Os). The study was divided in four parts: In part 1 memory enhancement was tested in normal rats. In part 2, 3, and 4 the effects of drugs were tested in Scopolamine-, Diazepam-, and Cyclosporine-induced amnesia. Hebb-Williams maze was used to test for learning and memory. Time required to trace food and number of errors in maze were noted. RESULTS: In normal rats, all test drugs showed significant reduction in time required to trace the food and number of errors after 24 h compared with vehicle control. Formulations 1 and 2 reduced the time required to trace food and number of errors and the results were comparable with positive control groups and comparators Tc and Pe. Formulations 1 and 2 reversed amnesia produced by Scopolamine, Diazepam, and Cyclosporine when compared with vehicle control and showed comparable results with those of positive control groups and comparators Tc and Pe. CONCLUSION: Formulations 1 and 2 demonstrated nootropic activity and both the formulations showed comparable nootropic activity with that of Tc and Pe alone.

An evaluation of the effects of nonselective and cardioselective ß-blockers on wound healing in Sprague Dawley rats.

OBJECTIVES: To investigate the effect of a nonselective ß-blocker (propranolol) and cardioselective ß-blocker (metoprolol) on wound healing in rats using incision and excision wound models and to compare the effect of these drugs on wound healing. MATERIALS AND METHODS: Propranolol and metoprolol were given orally. Sprague Dawley rats of either sex were used. Incision and excision wound models were used to evaluate the wound-healing activity. Effects of metoprolol and propranolol on tensile strength, period of epithelialization, and hydroxyproline content were observed. Histological analysis was done to see collagen deposition and inflammatory infiltrate. STATISTICAL ANALYSIS USED: The data was subjected to analysis of variance (ANOVA) followed by Scheffe's test. P < 0.05 was considered to be statistically significant. Statistical analysis was done using SPSS software version 15.0. RESULTS: Administration of propranolol or metoprolol was shown to decrease tensile strength, delay wound contraction and re-epithelialization, increase inflammatory infiltrate, and reduce collagen density and hydroxyproline levels. CONCLUSIONS: The results suggest that nonselective and cardioselective ß-blockers delay wound healing and these effects are mediated by ß1-receptors.

Evaluation of anti-ulcer effect of amlodipine in gastric ulcer models in rats.

AIMS: To study anti-ulcer effect of Amlodipine and compared it with ranitidine in indomethacin, alcohol and pyloric ligation-induced gastric ulcers in wistar rats. MATERIALS AND METHODS: Gastric ulcers were induced in Wistar albino rats by oral administration of indomethacin (200 mg/kg), alcohol (80%, 1 ml/100 gm) and by pyloric ligation. Antiulcer activity of amlodipine (0.5 mg/kg, i.p.) was observed either alone or in combination with ranitidine (15 mg/kg, i.p.), on ulcer index, gastric pH and gastric volume. Statistical analysis was done by ANOVA and unpaired one tailed 't' test. P<0.05 was considered statistically significant. RESULTS: Amlodipine produced significant (P<0.05) decrease in ulcer index and gastric pH as compared to control. It also produced significant (P<0.05) increase in gastric volume as compared to ranitidine. The anti-ulcer effects of ranitidine were significantly higher than that of amlodipine. Combination of amlodipine and ranitidine did not show significant increase in anti-ulcer activity as compared with ranitidine alone. CONCLUSIONS: Amlodipine produced significant anti-ulcer effects in all 3 experimental models. Amlodipine increased the volume of gastric secretions as compared to ranitidine.