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.
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ABSTRACT: Prepulse inhibition (PPI) of the acoustic startle reflex refers to the reduction of the startle response to an intense acoustic pulse stimulus when it is shortly preceded by a weak non-startling prepulse stimulus and provides a cross-species measure of sensory-motor gating. PPI is typically impaired in schizophrenia patients, and a similar impairment can be induced in rats by systemic scopolamine, a muscarinic cholinergic receptor antagonist that can evoke a range of cognitive and psychotic symptoms in healthy humans that are commonly referred to as the "anti-muscarinic syndrome" resembling some clinical features of schizophrenia. Scopolamine-induced PPI disruption has therefore been proposed as an anti-muscarinic animal model of schizophrenia, but parallel investigations in the mouse remain scant and the outcomes are mixed and often confounded by an elevation of startle reactivity. Here, we distinguished the PPI-disruptive and the confounding startle-enhancing effects of scopolamine (1 and 10mg/kg, i.p.) in C57BL/6 wild-type mice by showing that the latter partly stemmed from a shift in spontaneous baseline reactivity. With appropriate correction for between-group differences in startle reactivity, we went on to confirm that the PPI-disruptive effect of scopolamine could be nullified by clozapine pre-treatment (1.5mg/kg, i.p.) in a dose-dependent manner. This is the first demonstration that scopolamine-induced PPI disruption is sensitive to atypical antipsychotic drugs. In concert with previous data showing its sensitivity to haloperidol the present finding supports the predictive validity of the anti-muscarinic PPI disruption model for both typical and atypical antipsychotic drug action.Pharmacology Biochemistry and Behavior 12/2011; 101(1):107-14. · 2.82 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.
- European Neuropsychopharmacology 09/2011; 21. · 5.40 Impact Factor