Search

Background: In a variety of organisms, including mammals, caloric restriction improves metabolic status and lowers the incidence of chronic-degenerative diseases, ultimately leading to increased lifespan., Methodology/principal Findings: Here we show that knockout mice for Eps8, a regulator of actin dynamics, display reduced body weight, partial resistance to age- or diet-induced obesity, and overall improved metabolic status. Alteration in the liver gene expression profile, in behavior and metabolism point to a calorie restriction-like phenotype in Eps8 knockout mice. Additionally, and consistent with a calorie restricted metabolism, Eps8 knockout mice show increased lifespan. The metabolic alterations in Eps8 knockout mice correlated with a significant reduction in intestinal fat absorption presumably caused by a 25% reduction in intestinal microvilli length., Conclusions/significance: Our findings implicate actin dynamics as a novel variable in the determination of longevity. Additionally, our observations suggest that subtle differences in energy balance can, over time, significantly affect bodyweight and metabolic status in mice.

Hyperforin is one of the possible active principles mediating the antidepressant activity of Hypericum perforatum L. extracts. The ester derivative IDN 5491 (hyperforin-trimethoxybenzoate) showed antidepressant-like properties in the forced swimming test (FST) in rats, with no effect on open-field activity, when given as three intraperitoneal injections in 24 h at 3.125 and 6.25 mg/kg. The plasma concentrations of IDN 5491 were 30-50 microM, and those of hyperforin much lower but still close to those after effective doses of hyperforin-dicyclohexylammonium and Hypericum extract. This suggests that hyperforin plays a role in the antidepressant-like effect of the ester and of Hypericum extract. In vitro binding and uptake data showed that IDN 5491 is inactive on a wide panel of CNS targets at a concentration (14 microM) much higher than that measured in the brain of treated rats (0.3 microM). Like the extract, the antidepressant-like effect of IDN 5491 was blocked by (-)-sulpiride, a selective D2 receptor antagonist and by BD-1047, a selective sigma1 antagonist. Ex-vivo binding studies showed that brain sigma1 receptors are occupied after in vivo treatment with IDN 5491, possibly by an unknown metabolite or by endogenous ligand induced by hyperforin.

Rationale: Hyperforin has been identified as an active constituent of Hypericum perforatum but its importance in the antidepressant effect of this plant's extracts is not really known., Objective: To evaluate the antidepressant-like activity of two extracts in relation to the content of hyperforin and its plasma and whole brain concentrations, compared with a stable salt of hyperforin (dicyclohexylammonium; DCHA)., Methods: The effects of the extracts and hyperforin were evaluated in the rat forced swimming test. The specificity of the effects was demonstrated evaluating the rats' locomotor activity. Plasma and brain concentrations of hyperforin were determined by high performance liquid chromatography., Results: The 4.5% extract (but not the 0.5% extract) given as three IP injections in 24 h (3.12-6.25 mg/kg) reduced the total immobility of rats, yielding dose-related plasma concentrations of hyperforin. These concentrations were of a similar magnitude to those after hyperforin DCHA which also significantly reduced immobility when given on the basis of the hyperforin content of the 4.5% extract (0.14 and 0.28 mg/kg). However, hyperforin was undetectable in rat brain, possibly because of poor passage of the blood-brain barrier., Conclusion: These results support the view that hyperforin plays a key role in the antidepressant-like activity of Hypericum p. However, brain concentrations after effective doses are probably far from those active in vitro on the neurotransmitter mechanisms so far investigated.

Rationale: Changes in serotonin(1B) (5-HT(1B)) receptor function appear to modify the reinforcing properties of cocaine, but the direction of this effect is not completely clear. Pharmacological stimulation of 5-HT(1B) enhanced the rewarding properties of self-administered cocaine while attenuating the threshold-reducing effect of cocaine in the intracerebral brain stimulation procedure., Objective: The present study investigates how pharmacological modification of 5-HT(1B) receptor-mediated neurotransmission influence cocaine motivational properties in the conditioned place preference paradigm in rats., Methods: In separate groups of rats the motivational properties of CP 94,253, a selective 5-HT(1B) agonist, or GR 127935, a 5-HT(1B/D) receptor partial agonist, given alone or in combination, were determined. To evaluate their influence on cocaine-induced place conditioning, CP 94,253, that was found to be aversive, was given every day before each conditioning session, while GR 127935, which given alone had no effect, was administered only before cocaine conditioning sessions., Results: CP 94,253, injected IP at 2.5 and 10 (but not 0.5) mg/kg produced place aversion in the place conditioning paradigm. The aversive effect of 2.5 mg/kg CP 94,253 was completely reversed by 10 mg/kg SC GR 127935. Given before every conditioning session, CP 94,253 did not modify place conditioning by four injections of 10 mg/kg cocaine but at 2.5 mg/kg it potentiated a sub-threshold dose of cocaine. The place preference caused by these two drugs was completely reversed by 10 mg/kg GR 127935. The antagonism by GR 127935 of CP 94,253's effects was shown not to be due to the induction of state-dependent effects., Conclusion: The results suggest that stimulation of 5-HT(1B) receptors causes place aversion, and enhances the effect of low doses of cocaine in the conditioned place preference paradigm.