Evaluation of Acute and Subacute Oral Toxicity of the Ethanol Extract from Antidesma Acidum Retz

Toxicity tests of 95% ethanol extract of the root of Antidesma acidum were studied in male and female rats. The oral acute toxicity test at 5,000 mg/kg revealed that the ethanol extract did not produce toxic effects on signs, general behavious, mortality and gross appearance of internal organs of rats. Furthermore, the oral sub-acute toxicity test at the dose of 1,000 mg/kg/day displayed no significant changes in body and internal organs’ weights, normal hematological and clinical blood chemistry values. Histological examination also showed normal architecture of all internal organs. In conclusion, the ethanol extract of Antidesma acidum did not produce any toxicity in oral acute and suba-cute toxicity studies

Effect of pre- and post-treatment with Bacopa monnieri (Brahmi) on phencyclidine-induced disruptions in object recognition memory and cerebral calbindin, parvalbumin, and calretinin immunoreactivity in rats

P Piyabhan,1 P Tingpej,2 N Duansak11Division of Physiology, Department of Preclinical Science, Faculty of Medicine, Thammasat University, KlongLuang, Pathumthani, Thailand; 2Division of Microbiology, Department of Preclinical Science, Faculty of Medicine, Thammasat University, KlongLuang, Pathumthani, ThailandBackground: Decreased gamma-aminobutyric acid (GABA)-ergic neurons in the brain of both schizophrenic patients and animal models indicates that impairment of GABAergic function is implicated in pathophysiology of the disorder. Decreased GABAergic neurotransmission might be also involved in cognitive impairment, which is developed in schizophrenia. Brahmi (Bacopa monnieri) could be a new treatment and prevention for this cognitive deficit in schizophrenia by increasing GABAergic neurons to a normal level.Aim: The authors aimed to study cognitive-enhancement- and neuroprotective-effects of Brahmi on novel object recognition memory and GABAergic neuronal density, defined by the presence of calcium binding proteins (CBPs; calbindin (CB), parvalbumin (PV), and calretinin (CR)) in a sub-chronic (2 mg/kg, Bid, ip) phencyclidine (PCP) rat model of schizophrenia.Materials and methods: In the cognitive-enhancement-effect study rats were assigned to three groups; Group-1: Control, Group-2: PCP-administration, and Group-3: PCP+Brahmi. In the neuroprotective-effect study rats were assigned to three groups; Group-1: Control, Group-2: PCP-administration, and Group-3: Brahmi+PCP. A discrimination ratio (DR) representing cognitive ability was obtained from the novel object recognition task. CB, PV, and CR immunodensity were measured in the prefrontal cortex, striatum, and cornuammonis fields 1–3 (CA1–3) using immunohistochemistry.Results: Reduced DR was found in the PCP group, which occurred alongside reduced CB, PV, and CR in all brain regions except for CR in the striatum and CA1–3 in the cognitive-enhancement-effect study. PCP+Brahmi showed a higher DR score with increased CB in the prefrontal cortex and striatum, increased PV in the prefrontal cortex and CA1–3, and increased CR in the prefrontal cortex. The Brahmi+PCP group showed higher DR score with increased CB in all areas, increased PV in the striatum, and increased CR in the prefrontal cortex and striatum.Conclusion: The present study demonstrated the effects, both partial restoration of cognitive deficit and neuroprotection, of Brahmi, and elucidated its underlying mechanism of actions via increasing GABAergic neurons in a PCP-induced schizophrenic-like model.Keywords: schizophrenia, cognitive impairment, Bacopa monnieri, calbindin, parvalbumin, calretini

Lentiviral Delivery of a Vesicular Glutamate Transporter 1 (VGLUT1)-Targeting Short Hairpin RNA Vector Into the Mouse Hippocampus Impairs Cognition

Glutamate is the principle excitatory neurotransmitter in the mammalian brain, and dysregulation of glutamatergic neurotransmission is implicated in the pathophysiology of several psychiatric and neurological diseases. This study utilized novel lentiviral short hairpin RNA (shRNA) vectors to target expression of the vesicular glutamate transporter 1 (VGLUT1) following injection into the dorsal hippocampus of adult mice, as partial reductions in VGLUT1 expression should attenuate glutamatergic signaling and similar reductions have been reported in schizophrenia. The VGLUT1-targeting vector attenuated tonic glutamate release in the dorsal hippocampus without affecting GABA, and selectively impaired novel object discrimination (NOD) and retention (but not acquisition) in the Morris water maze, without influencing contextual fear-motivated learning or causing any adverse locomotor or central immune effects. This pattern of cognitive impairment is consistent with the accumulating evidence for functional differentiation along the dorsoventral axis of the hippocampus, and supports the involvement of dorsal hippocampal glutamatergic neurotransmission in both spatial and nonspatial memory. Future use of this nonpharmacological VGLUT1 knockdown mouse model could improve our understanding of glutamatergic neurobiology and aid assessment of novel therapies for cognitive deficits such as those seen in schizophrenia