Evidence that the beta-acids fraction of hops reduces central GABAergic neurotransmission.

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.

Activity of single components of Ferula hermonis on male rat sexual behavior.

The influence of the single components of Ferula hermonis extract on sexual behavior was studied in male rats. Sexually potent and sluggish/impotent animals were orally treated acutely (2.5 mg/kg) and subchronically (0.25 mg/kg/day for 10 days) with ferutinin, teferdin and teferin. Ferutinin alone acutely administered in potent rats was able to reduce mount and intromission latencies, while in sluggish/impotent animals, it induced the same effects and additionally shortened the ejaculation latency, as teferdin did. Both substances increased testosterone levels in rats. Unlike teferdin, ferutinin subchronically administered in potent rats negatively affected appetitive and consummatory sexual behavior, reducing also testosterone serum levels. In conclusion, if repetitively administered, ferutinin was able to stimulate sexual behavior after acute ingestion, but exerted a negative influence on the sexual capacity of potent male rats, whereas teferdin only improved copulatory performance of sluggish/impotent animals.

New insight in the neuropharmacological activity of Humulus lupulus L.

The purpose of the present study was to investigate the effects of Humulus lupulus CO2 extract and its fraction containing alpha-acids on the central nervous system of rats. Both tested substances were able to prolong pentobarbital sleeping time, without affecting the latency to the loss of the righting reflex. This effect was dose-dependent, starting from a minimal dose of 10 mg/kg. Neither the extract nor its alpha-acid fraction affected the locomotor activity in the open field test or exerted an anxiolytic effect in rats submitted to the elevated plus-maze test. Interestingly both compounds reduced the immobility time during the behavioral despair test when administered three times (24, 5 and 1 h) before the test. In conclusion this report shows that Humulus lupulus CO2 extract exerts: (a) a pentobarbital sleep-enhancing property without influencing the motor behavior of rats; (b) an antidepressant activity. The same effects were elicited by the administration of the Humulus lupulus fraction containing alpha-acids, which can be considered as the major responsible for the enhanced pentobarbital effect and for the antidepressant property.