1. Evidence that the beta-acids fraction of hops reduces central GABAergic neurotransmission.
- Author
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Zanoli P, Zavatti M, Rivasi M, Brusiani F, Losi G, Puia G, Avallone R, and Baraldi M
- Subjects
- Animals, Antidepressive Agents pharmacology, Binding, Competitive drug effects, Carbon Dioxide, Central Nervous System drug effects, Cerebellum cytology, Cerebellum drug effects, Cerebellum metabolism, Depression, Chemical, Electrophysiology, GABA Antagonists, Male, Maze Learning drug effects, Motor Activity drug effects, Pentobarbital pharmacology, Picrotoxin, Rats, Rats, Sprague-Dawley, Receptors, GABA-A drug effects, Seizures chemically induced, Seizures prevention & control, Sleep drug effects, Solvents, Swimming psychology, Humulus chemistry, Plant Extracts pharmacology, Synaptic Transmission drug effects, gamma-Aminobutyric Acid physiology
- Abstract
Humulus lupulus (hops) is traditionally used as a tranquilizing herbal remedy. Here, we investigated the in vivo and in vitro effect of hop beta-acids on central nervous system function. Oral administration of beta-acids (5-10mg/kg) in rats produced an increased exploratory activity in the open field, a reduction in the pentobarbital hypnotic activity and a worsening of picrotoxin-induced seizures. When dosed at 10mg/kg, beta-acids increased, in the elevated plus maze, open arm entries reducing in parallel those in closed arms. In the forced swimming test, we observed a reduction in the immobility time that could suggest an antidepressant-like activity. Electrophysiological studies performed on cerebellar granule cells in culture showed that the beta-acids fraction decreased GABA-evoked current in a dose-dependent way. The effect was not inhibited by the benzodiazepine antagonist Ro 15-1788. Benzodiazepine receptors involvement was also excluded by [(3)H]-Ro 15-1788 binding assay. In conclusion, the behavioral effects of beta-acids fraction could be explained by a reduction in the GABAergic activity although we cannot rule out the involvement of other neurotransmitter systems.
- Published
- 2007
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