Proapoptotic and prepulse inhibition (PPI) disrupting effects of Hypericum perforatum in rats.
ABSTRACT St. John's wort extract is commonly used as a wound healing, anti-inflammatory, anxiolytic, diuretic, antibiotic, antiviral and cancer chemoprotective agent. It also has nootropic and/or antiamnestic effects.
Prepulse inhibition (PPI) of startle response is a valuable paradigm for sensorimotor gating processes. A previous study indicated that single administration of St. John's wort extract (500 mg/kg) caused PPI disruption in rats. The effect of antiamnestic doses of the extract on PPI has not been investigated despite the coexistence of impaired memory and PPI deficit in some neurological disorders.
The effects of acute (500 mg/kg) and chronic (200mg/kg for 3 days) administration of St. John's wort extract were investigated for its antiamnestic activity. The effects of administration of the antiamnestic dose of the extract and hyperforin, its main active component, were tested on PPI of an acoustic startle response in rats. This study also investigated the proapoptotic effect of hyperforin in animals, demonstrating PPI deficit, by electrophoresis of DNA isolated from selected brain areas.
Disruption of PPI resulted after treatment of rats with an antiamnestic dose of the extract (200mg/kg for 3 days) and with hyperforin. Gel electrophoresis showed DNA fragmentation of the cortices of hyperforin-treated animals exhibiting PPI deficit.
The exacerbating effect of St. John's wort extract on PPI deficit may provide a limitation for using the extract to manage cognitive disturbance in psychotic and Huntington's disease patients manifesting PPI deficit.
- European Neuropsychopharmacology 09/2011; 21. DOI:10.1016/S0924-977X(11)70456-4 · 5.40 Impact Factor
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ABSTRACT: Deterioration in attention and related processes is an early sign in schizophrenia predictive of disease development. Amongst the various translational paradigms for assessing attention in rodents, it is not known if they are equivalent in detecting individual differences. Answers here are pertinent to their use in the general human population for identifying individuals at high risk of developing schizophrenia. The present study employed a within-subject approach to examine in mice two common paradigms for assessing attention that differ markedly in their implementation. An operant-based two-choice visual discrimination task (2-CVDT) that depends on effortful attention to brief visual cues was contrasted with prepulse inhibition (PPI) of the acoustic startle reflex, a well-established test of pre-attentive gating whereby processing of a startle-eliciting stimulus is inhibited by a preceding weak prepulse stimulus. Here, we revealed a correlation showing that individual mice with low PPI tended to perform poorly in the 2-CVDT in terms of choice accuracy but not response speed. This specific positive correlation suggests that the two readouts might be regulated via common attentional mechanisms, which might be critically dependent on normal muscarinic and N-methyl-d-asparate receptor functions. As demonstrated here, blockade of either receptor type by scopolamine or dizocilpine impaired 2-CVDT performance at doses that have been shown to disrupt PPI in mice. Further studies contrasting these two paradigms would be warranted to characterize the possible underlying psychological constructs that give rise to this correlation and to clarify whether the two paradigms may effectively capture schizophrenia-related cognitive deficits belonging to orthogonal domains.Behavioural brain research 10/2010; 217(1):178-87. DOI:10.1016/j.bbr.2010.10.021 · 3.39 Impact Factor
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ABSTRACT: Nootropic drugs used as a memory enhancer can improve thinking, memory, and alertness in people with Alzheimer's disease and other disease that affect the mind. Memory is perhaps the most vital of all aspects that differentiates human beings from other animals. However, memory can become faulty due to several reasons, and in that case the person is not able to make full use of his or her potentials. Since ages, drugs and natural remedies have been prescribed to enhance memories in people. 4 million people are thought to be suffering from age related memory and increased risk of developing Alzheimer's disease. Although several nootropic drugs are available to treat memory problems. In recent years research on medicinal plants have been studied for nootropic activity. Bacopa monnieri (Brahmi), Evolvulus alsinoides (Shankhpushpi), Withania somnifera (Ashwagandha), Acorus calamus (Bach) etc., are used as a memory enhancer drugs. The abstract refers to several plants with their activity. The main aim of this article is to give up the data reviews on plants with nootropic properties. INTRODUCTION: Nootropics also referred to as smart drugs, memory enhancers, and cognitive enhancers, are drugs, supplements, nutraceuticals, and functional foods that are purported to improve mental functions such as cognition, memory, intelligence, motivation, attention, and concentration.