Brain neurotransmitter receptor binding and nootropic studies on Indian Hypericum perforatum Linn.

Abstract

The high affinity binding sites for serotonin and benzodiazepine in the frontal cortex, for dopamine in the striatum and muscarinic cholinergic receptors in the hippocampus were investigated in the brains of Charles Foster rats treated for 3 days. Transfer latency on elevated plus maze (TL), passive and active avoidance behaviour (PA and AA) and electroconvulsive shock (ECS) induced amnesia were also studied. Pilot studies indicated that single dose administration of Indian Hypericum perforatum (IHp) had little or no acute behavioural effects and hence the extract of IHp was administered orally at two dose levels (100 and 200 mg/kg, p.o.) once daily for 3 consecutive days, while piracetam (500 mg/kg, i.p.), a clinically used nootropic agent, was administered acutely to rats as the standard nootropic agent. Control rats were treated with an equal volume of vehicle (0.3% carboxymethyl cellulose). The results indicate that IHp treatment caused a significant decrease in the binding of [3H] spiroperone (DA-D2 receptor) to the striatum and an increase in the binding of [3H] ketanserin (5-HT2A receptor) and [3H] flunitrazepam (BDZ receptor) to the frontal cortex in rats. Preliminary pharmacological studies with IHp extract indicate the presence of two major behavioural actions, namely, antidepressant and anxiolytic. The present findings tend to elucidate the mechanism of earlier observations, the downregulation of the dopamine D2 receptor being consonant with anxiolytic and the upregulation of 5-HT2A and BDZ receptors being consonant with antidepressant activity. Piracetam when given alone, shortened the TL on days 1, 2 and 9 day and also antagonized the amnesic effects of ECS on the TL significantly, whereas IHp antagonized the amnesia produced by ECS. IHp had no significant effect per se on the retention of the PA in rats but produced a significant reversal of ECS induced PA retention deficit. Piracetam showed a significant facilitatory effect per se on PA retention and also reversed the ECS induced impaired PA retention. In the AA test, piracetam facilitated the acquisition and retention of AA in rats but IHp had no effect per se. Both the doses of IHp and piracetam significantly attenuated the ECS induced impaired retention of AA. These results indicate a possible nootropic action of IHp in amnesic animals, which was comparable qualitatively to piracetam.

Potential medicinal plants for CNS disorders: an overview

“…Additionally, IHp showed antidepressant, anxiolytic, antiamnestic, antiinflammatory and analgesic and antistress activities in various animal models 2000a;2000b;2001a;2001b;Zhang, 2004). Some researchers recently found that HP had neuroprotective effects and diminished cognitive impairment and improved spatial learning and memory (Trofimiuk et al, 2005;Silva et al, 2004;Kumar et al, 2003;Widy-Tyszkiewicz et al, 2002;Kumar et al, 2002;Klusa et al, 2001;Kumar et al, 2000c). Other studies confirmed that hyperforin released hippocampal acetylcholine (Kiewert et al, 2004;Buchholzer et al, 2002) and HP reduced the degradation rate of acetylcholine (Re et al, 2003).…”

The selective effect of N-feruloylserotonins isolated from Leuzea carthamoides on nociception and anxiety in rats

“…of bioactive substances from medicinal plants influencing serotonergic transmission has been examined in connection with Hypericum perforatum; the plant proved to have anxiolytic and antidepressant effects on rats. These effects were mediated by up-regulation of 5-HT 2A receptors (Kumar et al, 2002). The application of an alcohol extract of Hypericum caprifoliatum or Hypericum polyanthemum has been shown to induce antinociceptive effects in rats, which were probably mediated through the activation of the opioid system (Viana et al, 2003).…”

Effects of ethanolic extract of Fumaria indica L. on rat cognitive dysfunctions

“…[1112] In short, the plus maze consisted of two opposite open arms crossed with two enclosed arms of the same dimensions (50 × 10 cm), with walls 40 cm high. The arms were connected with a central square (10 × 10 cm) to give the apparatus a plus sign appearance.…”

“…[1213] Briefly, on day 1, a rat was placed in a white box and the time taken to enter into the dark box was noted [step through latency (STL) 1]. As soon as the rat entered the dark box, the guillotine door was closed and foot electric shock (0.5 mA, 3 sec) was delivered.…”