Cognitive enhancement effects of Bacopa monnieri (Brahmi) on novel object recognition and NMDA receptor immunodensity in the prefrontal cortex and hippocampus of sub-chronic phencyclidine rat model of schizophrenia.
BACKGROUND
Cognitive impairment is a common characteristic in schizophrenia that cannot be attenuated by antipsychotics. Brahmi, popularly known as a cognitive enhancer might be a new frontier of cognitive deficit treatment in schizophrenia.


OBJECTIVE
To study effects of Brahmi on attenuation at cognitive deficit and cerebral glutamate/N-methyl-D-aspartate (NMDA) receptor density in sub-chronic phencyclidine (PCP) rat model of schizophrenia.


METHODS
Rats were administered PCP or vehicle. Half of the PCP-group was treated with Brahmi. Discrimination ratio (DR) representing cognitive ability was obtained from novel object recognition task. NMDA immunodensity was measured in prefrontal cortex, striatum, cornu ammonis fields 1 to 3 of hippocampus (CA1-3), and dentate gyrus (DG) using immunohistochemistry.


RESULTS
DR in PCP-group was significantly decreased compared with control. This occurred alongside NMDA up-regulation in prefrontal cortex and CA1-3, but not in striatum and DG. PCP with Brahmi showed a significant increase in DR score compared with PCP alone. This occurred alongside significant decrease in NMDA immunodensity in prefrontal cortex and CA1-3. No significant difference in cerebral NMDA immunodensity was observed between PCP with Brahmi and control.


CONCLUSIONS
Cognitive deficit observed in PCP-administered rats was mediated by NMDA up-regulation in prefrontal cortex and CA1-3. Interestingly, Brahmi could recover this cognitive deficit by decreasing NMDA density in these brain areas to normal.
Department of Preclinical Science, Faculty of Medicine, Thammasat University, Rangsit Campus, Pathumthani, Thailand. taipritsana@yahoo.com
Pritsana
P
Piyabhan
Thanitsara
T
Wetchateng
Seewaboon
S
Sireeratawong
D000818:Animals; D034681:Bacopa; D003071:Cognition; D003072:Cognition Disorders / Q000188:drug therapy*; D004195:Disease Models, Animal; D006213:Hallucinogens / Q000009:adverse effects; D006624:Hippocampus / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008297:Male; D018697:Nootropic Agents / Q000494:pharmacology*; D010622:Phencyclidine / Q000009:adverse effects; D008517:Phytotherapy; D017397:Prefrontal Cortex / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate; D012559:Schizophrenia / Q000139:chemically induced
D006213:Hallucinogens; D018697:Nootropic Agents; D016194:Receptors, N-Methyl-D-Aspartate; D010622:Phencyclidine