Pre-exposure prophylactic mucoadhesive sodium alginate microsphere laden pessaries for intravaginal delivery of tenofovir disoproxil fumarate

The research aimed to develop novel bioadhesive sodium alginate (Na-Alg) microspheres laden pessaries for intravaginal delivery of tenofovir disoproxil fumarate (TDF), to overcome limitations of conventional dosage forms. Twelve batches of microspheres formulated by emulsification gelation method indicated that drug-polymer ratios and polymer type affected particle size, drug release, and entrapment efficiency (%EE). Microspheres of batch EH-8 with drug: polymer ratio of 1:4 containing equal amounts of Na-Alg and HPMC K100M displayed optimal %EE (62.09 ± 1.34 %) and controlled drug release (97.02 ± 4.54 % in 12 h). Particle size analysis in Matersizer indicated that microspheres (EH-8) displayed a surface-mean diameter of 11.06 ± 0.18 μm. Ex-vivo mucoadhesion studies on rabbit mucosa indicated that microspheres (EH-8) adhered well for 12 h. Microspheres integrated into pessaries displayed a sustained release profile (95.31 ± 1.37 % in 12 h) in simulated vaginal fluid. In vivo studies in rabbits indicated that pessaries displayed a significantly higher Cmax (41.18 ± 3.57 ng/mL) (P < 0.005) and reduced Tmax (1.00 ± 0.01 h) (P < 0.0001) of TDF concentrations in vaginal fluid compared to oral tablets. The microparticulate pessaries with the ability to elicit higher vaginal fluid levels in the crucial initial hours of insertion demonstrates a potential novel platform to offer better self-protection to HIV-negative women against HIV during sexual intercourse.

Neuroprotective effect of Celastrus paniculatus on chronic stress-induced cognitive impairment

Objective:

Several studies report that chronic stress results in impaired spatial learning and working memory and enhanced anxiety-like behavior. However, not many studies have looked into the possible ways of reversing stress-induced deficits. Celastrus paniculatus (CP), a traditional ayurvedic herbal medicine, was used to treat cognitive deficits in mentally retarded children. CP oil has been reported to have neuroprotective and antioxidant activities. However, the effects of CP oil on chronic stress-induced cognitive deficits are unclear. In the present study, we intended to analyze the neuroprotective effects of CP oil on stress-associated cognitive dysfunctions.

Materials and Methods:

Chronic stress was induced by subjecting rats to restrainers for 6 h a day for 21 days. CP oil (400, 600 mg/kg) or vehicle was administered intraperitoneally (i.p.) after stress protocol once a day over the next 14 days. Groups used in the present study: normal control, stress, stress + vehicle, stress + CP oil at 2 different doses (400 and 600 mg/kg, i.p.). After the drug treatment, open field and elevated plus maze (EPM) were used to analyze anxiety-like behavior, and partially baited radial arm maze (RAM) and T-maze were used to evaluate spatial learning and memory capabilities. Analysis has been done using two-way ANOVA followed by Bonferroni's post hoc test and one-way ANOVA followed by Tukey's post hoc test.

Results:

Stressed rats showed enhanced anxiety-like behavior in EPM (P < 0.001) and impaired performance in RAM (P < 0.001) and T-maze tasks (P < 0.001) compared to normal animals. In contrast, CP oil treatment to these rats improved their performance in both RAM (P < 0.001) and T-maze (P < 0.001). In addition, CP oil significantly reduced stress-induced anxiety behavior (P < 0.001).

Conclusion:

Chronic treatment with CP oil is to improve cognitive abilities in chronically stressed rats. The current study provides a novel perspective on beneficial effect of herbal therapy on stress-induced cognitive dysfunctions.

Environmental enrichment ameliorates chronic immobilisation stress-induced spatial learning deficits and restores the expression of BDNF, VEGF, GFAP and glucocorticoid receptors

Severe and prolonged stress is the main environmental factor that precipitates depression, anxiety and cognitive dysfunctions. On the other hand, exposure to environmental enrichment (EE) has been shown to induce progressive plasticity in the brain and improve learning and memory in various neurological and psychiatric disorders. It is not known whether exposure to enriched environment could ameliorate chronic immobilisation stress-induced cognitive deficits and altered molecular markers. Hence, in the present study we aimed to evaluate the effect of enriched environment on chronic immobilisation stress (CIS) associated changes in spatial learning and memory, behavioural measures of anxiety, depression and molecular markers as well as structural alterations. Male Wistar rats were subjected to chronic immobilisation stress for 2h/day/10days followed by 2weeks of exposure to EE. CIS resulted in weight loss, anhedonia, increased immobility, spatial learning and memory impairment, enhanced anxiety, and reduced expression of BDNF, VEGF, GFAP and glucocorticoid receptors (GR) in discrete brain regions. Interestingly, stressed rats exposed to enrichment ameliorated behavioural depression, spatial learning and memory impairment and reduced anxiety behaviour. In addition, EE restored BDNF, VEGF, GFAP and GR expression and normalized hypotrophy of dentate gyrus and hippocampus in CIS rats. In contrast, EE did not restore hypertrophy of the amygdalar complex. Thus, EE ameliorates stress-induced cognitive deficits by modulating the neurotrophic factors, astrocytes and glucocorticoid receptors in the hippocampus, frontal cortex and amygdala.

Enriched environment restores hippocampal cell proliferation and ameliorates cognitive deficits in chronically stressed rats

Adult neurogenesis, particularly in the subgranular zone, is thought to be linked with learning and memory. Chronic stress inhibits adult hippocampal neurogenesis and also impairs learning and memory. On the other hand, exposure to enriched environment (EE) is reported to enhance the survival of new neurons and improve cognition. Accordingly, in the present study, we examined whether short-term EE after stress could ameliorate the stress-induced decrease in hippocampal cell proliferation and impairment in radial arm maze learning. After restraint stress (6 hr/day, 21 days) adult rats were exposed to EE (6 hr/day, 10 days). We observed that chronic restraint stress severely affected formation of new cells and learning. Stressed rats showed a significant decrease (70%) in the number of BrdU (5-bromo-2'-deoxyuridine)-immunoreactive cells and impairment in the performance of the partially baited radial arm maze task. Interestingly, EE after stress completely restored the hippocampal cell proliferation. On par with the restoration of hippocampal cytogenesis, short-term EE after stress resulted in a significant increase in percentage correct choices and a decrease in the number of reference memory errors compared with the stressed animals. Also, EE per se significantly increased the cell proliferation compared with controls. Furthermore, stress significantly reduced the hippocampal volume that was reversed after EE. Our observations demonstrate that short-term EE completely ameliorates the stress-induced decrease in cell proliferation and learning deficit, thus demonstrating the efficiency of rehabilitation in reversal of stress-induced deficits and suggesting a probable role of newly formed cells in the effects of EE.

Neonatal clomipramine induced endogenous depression in rats is associated with learning impairment in adulthood

Clinical studies show cognitive impairment in depression. However, the neural substrates underlying these remain elusive. Hence, we have examined the effect of neonatal clomipramine treatment on cognition in adulthood. The neonatal clomipramine treated rats displayed a profound impairment in partially baited 8-arm radial maze task. This work provides a novel perspective into neural basis of depression associated cognitive changes and help in development of therapeutic strategies to treat depression related memory dysfunctions.