Effects of caffeine on social behavior, exploration and locomotor activity: interactions with ethanol

The effects of caffeine and its interaction with ethanol were examined in a test of social behavior and a holeboard test of exploration and locomotion. Male mice were injected i.p. with 15, 30 or 60 mg/kg caffeine alone or in combination with 2 g/kg ethanol. The animals were then put in pairs into a familiar arena, or examined individually in the holeboard. Only the highest dose of caffeine (60 mg/kg) had a significant effect on the time spent in social interaction and motor activity in the social behavior test: both measures were reduced. The duration and frequency of avoidance-irritability behavior was dose-dependently increased by caffeine. In the holeboard, caffeine caused a dose-dependent increase in locomotor activity. 30 mg/kg caffeine reversed the ethanol-induced reduction of time spent in social interaction, and 60 mg/kg caffeine antagonized the ethanol-induced increase in locomotor activity in both the social behavior and holeboard tests. Caffeine's effects on ethanol-induced behavioral changes are compared with those of other drugs.     

Augmentation of the NO-cGMP cascade induces anxiogenic-like effect in mice.

Several studies have reported the anxiolytic-like effects of various nitric oxide synthase inhibitors in distinct animal models. However, in the context of anxiety, the possible involvement of cyclic GMP, believed to be one of the main targets of NO, remains obscure. Cyclic GMP is degraded by the specific phosphodiesterases in the brain. Therefore, we studied the effect of the selective phosphodiesterase type 5 inhibitor sildenafil in the mouse elevated plus-maze test of anxiety and in the open field test of locomotion. We found that sildenafil (0.05-10 mg/kg i.p.) alone did not affect the behavior of animals in the plus-maze or open field tests, but the anxiogenic beta-carboline DMCM given in a subconvulsive dose (2 mg/kg i.p.) decreased the time spent on open arms in the elevated plus-maze. Treatment with the NO precursor L-arginine (200 mg/kg i.p.) did not modify the behavior of animals in the plus-maze, however, when sildenafil (1 mg/kg i.p.) was administered in combination with L-arginine (200 mg/kg i.p.), both the time spent on the open arms and the percentage of open arm visits were significantly decreased. We conclude that augmentation of the NO-cGMP cascade induces anxiogenic-like effect in mice.     

Cross-tolerance studies between caffeine and (-)-N6-(phenylisopropyl)-adenosine (PIA) in mice

Chronic administration of caffeine to mice (1 mg/ml in drinking water X 14 d) led to a downward shift in the dose-response curve for the locomotor effects of caffeine. Caffeine was also less effective as an antagonist against (-)-(N6-phenylisopropyl)-adenosine (PIA)-induced analgesia in the tail flick assay in these animals. The dose-response curves of PIA for both analgesia and locomotor depression were shifted to the left in animals chronically administered caffeine. In mice chronically administered PIA (1 mg/kg/d X 14 d), the dose-response curves of PIA for both analgesia and locomotor depression were shifted to the right. The dose-response curve for the locomotor effects of caffeine was shifted to the left, and caffeine exhibited greater antagonist activity against the analgesic action of PIA in these animals. There was no change in the Kd or Bmax values of either 3H-PIA or 3H-diethylphenylxanthine (DPX, a potent adenosine receptor antagonist) in mice chronically administered PIA. The Bmax values for both 3H-PIA and 3H-DPX were significantly increased, while the Kd values were not changed in mice chronically administered caffeine. There was no detectable change in the brain levels of either PIA or caffeine in animals chronically treated with either drug. The results demonstrate that chronic administration of caffeine increases the sensitivity of mice to the actions of PIA and vice versa, providing supportive evidence for the interaction of these drugs at the same receptor, which is probably an adenosine receptor.     

Potentiation by caffeine of the frequencies of micronuclei induced by mitomycin C and cyclophosphamide in young mice

Employing the micronucleus test in mouse bone marrow and in fetal mouse liver, the possible clastogenicity of caffeine as well as its influence on MMC- and CP-induced micronucleus levels were studied. The treatment of male and female C57Bl or BDF1 (C57Bl x DBA2) mice with caffeine (1 or 3 x 50 mg/kg and 100 mg/kg, s.c.) had no clastogenic effect in mouse bone marrow or in the fetal livers and maternal bone marrow when pregnant mice were injected with caffeine on day 16-17 of gestation. MMC (2.0 mg/kg, i.p.) increased up to 10-30-fold the number of MNPCEs in bone marrow compared to a 3-7 fold elevation of MNPCEs in fetal liver. A similar effect was also established in pregnant mice treated with CP (30 mg/kg, i.p.). No significant sex differences in spontaneous and MMC- or CP-induced MNPCEs levels were established in C57Bl and BDF1 mice. However, a significantly higher spontaneous rate of MNPCEs as well as a better-expressed responsiveness to the clastogenic activity of MMC and CP were established in C57Bl compared to BDF1 mice. The pregnancy had no effect on MMC- or CP-induced clastogenicity although a tendency to a decreased sensitivity to the damaging activity of MMC seemed to be detected in pregnant C57Bl mice compared to virgin female animals. The combined treatment of mice with caffeine (3 x 100 mg/kg) and MMC or CP caused an up to 45-49% potentiation of clastogenesis in the bone marrow of male, female and pregnant female C57Bl and BDF1 mice but not in fetal mouse livers.     

Composition and antifungal activity of the essential oil from the rhizome and roots of Ferula hermonis

The analysis of the essential oil from rhizome and roots of Ferula hermonis Boiss. (Apiaceae) by GC-FID, GC-MS and 13C NMR allowed the identification of 79 constituents, more than 90% of the oil, the major one being α-pinene (43.3%), followed by α-bisabolol (11.1%) and the unusual acetylenic compound 3,5-nonadiyne (4.4%). The antifungal activity of the essential oil before and after fractionation was assayed against several yeasts and filamentous fungi. Purification of the active fractions afforded 3,5-nonadiyne, α-bisabolol, jaeschkeanadiol angelate, α-bisabolol oxide B and trans-verbenol, as well as two purified fractions, one of them (JB73) with 73% of jaeschkeanadiol benzoate and the other with 50% of spathulenol. Determination of MIC and MFC values of all these products evidenced strong antifungal activities for JB73 and 3,5-nonadiyne. Particularly, against the dermatophyte Tricophyton mentagrophytes, MIC and MFC values were 0.25 μg/ml for JB73, and 8 μg/ml for 3,5-nonadiyne, the former being more active than amphotericin B and nystatin.     

Stimulatory effect of oral administration of green tea and caffeine on locomotor activity in SKH-1 mice

Administration of green tea or caffeine was shown previously to inhibit ultraviolet B light-induced carcinogenesis in SKH-1 mice, and this effect was associated with a reduction in dermal fat. In the present study, oral administration of 0.6% green tea (6 mg tea solids/ml) or 0.04% caffeine (0.4 mg/ml; equivalent to the amount of caffeine in 0.6% green tea) as the sole source of drinking fluid to SKH-1 mice for 15 weeks increased total 24 hr locomotor activity by 47 and 24%, respectively (p<0.0001). Oral administration of 0.6% decaffeinated green tea (6 mg tea solids/ml) for 15 weeks increased locomotor activity by 9% (p<0.05). The small increase in locomotor activity observed in mice treated with decaffeinated green tea may have resulted from the small amounts of caffeine still remaining in decaffeinated green tea solutions (0.047 mg/ml). The stimulatory effects of orally administered green tea and caffeine on locomotor activity were paralleled by a 38 and 23% increase, respectively, in the dermal muscle layer thickness. In addition, treatment of the mice with 0.6% green tea or 0.04% caffeine for 15 weeks decreased the weight of the parametrial fat pad by 29 and 43%, respectively, and the thickness of the dermal fat layer was decreased by 51 and 47%, respectively. These results indicate that oral administration of green tea or caffeine to SKH-1 mice increases locomotor activity and muscle mass and decreases fat stores. The stimulatory effect of green tea and caffeine administration on locomotor activity described here may contribute to the effects of green tea and caffeine to decrease fat stores and to inhibit carcinogenesis induced by UVB in SKH-1 mice.     

Complete,reversible, drug-specific tolerance to stimulation of locomotor activity by caffeine

The development of tolerance to caffeine-induced stimulation of locomotor activity was evaluated in rats maintained chronically on average daily doses of 160 mg/kg or more of caffeine by the method of scheduled access to drinking water containing the drug. Dose-response curves were determined for caffeine (6.25–100 mg/kg) and $\text{d}$-amphetamine (0.39–6.4 mg/kg) during chronic drug treatment. In addition, the caffeine curve was redetermined 2–3 weeks after removal of the drug from the drinking water. A control group that had scheduled access to drug-free tap water was also tested. Caffeine produced dose-related increases in the locomotor activity of the controls but failed to modify locomotor activity of the chronic caffeine group. In contrast, $\text{d}$-amphetamine increased locomotor activity of both groups comparably. Spontaneous locomotor of the chronic caffeine group was reduced significantly for 4 days after drug-free tap water was substituted for the caffeine solution. The return of spontaneous locomotor activity to baseline values was associated with restored sensitivity to caffeine-induced stimulation of locomotor activity. Thus, chronic administration of caffeine to rats results in the development of tolerance to caffeine-induced stimulation of locomotor activity that is virtually complete, pharmacologically specific, and fully reversible when drug treatment is stopped. Decreases in spontaneous locomotor activity after abrupt termination of chronic caffeine administration follow a time course consistent with a drug withdrawal syndrome.     

Behavioural characterisation of young adult transgenic mice overexpressing galanin under the PDGF-B promoter

The behavioural phenotype of transgenic mice (3- to 5-months old) overexpressing galanin (GalOE) under the platelet-derived growth factor B (PDGF-B) promoter was evaluated in a battery of tests, including open field, locomotor cages, light-dark exploration test, elevated plus-maze and the Porsolt forced swim test. Learning and memory were assessed in the passive avoidance and the Morris water maze tasks. No difference between genotypes was found in exploratory activity in the open field. GalOE mice showed a slight increase in spontaneous locomotor activity assessed in the locomotor cages, but the amphetamine-induced increase in locomotor activity was somewhat lower in GalOE mice. Anxiety-like behaviour in the three different tests including open field, light-dark exploration and elevated plus-maze did not differ between genotypes. In the Porsolt forced swim test, GalOE mice displayed an increased time of immobility, indicative of increased learned helplessness possibly reflecting increased stress-susceptibility and/or depression-like behaviour. GalOE mice showed normal learning and memory retention in the passive avoidance and the Morris water maze tasks. These data support the hypothesis that galanin may have a role in functions related to mood states including affective disorders.     

CGS 15943, a nonxanthine adenosine receptor antagonist: effects on locomotor activity of nontolerant and caffeine-tolerant rats

CGS 15943 (0.1-10 mg/kg, IP) dose-dependently increased the locomotor activity of rats to the same extent as caffeine (1.0-100 mg/kg, IP) did and was approximately 26 times more potent than caffeine. N-Ethylcarboxamidoadenosine (0.001-0.01 mg/kg, SC), an analog of adenosine, dose-dependently decreased locomotor activity; this effect was antagonized surmountably by concurrent administration of CGS 15943. The apparent pA2 value for this interaction, 6.57, was approximately 1.5 log-units (28-fold) higher than the pA2 for caffeine-NECA reported previously. Rats consuming 70 mg/kg/day of caffeine via their drinking water were tolerant to the stimulation of locomotor activity induced by both caffeine and CGS 15943. These results suggest that caffeine and CGS 15943 increase locomotor activity by a common mechanism of action possibly involving adenosine receptors or a cellular element conformationally similar to adenosine receptors.     

The participation of CCK-8-ergic mechanisms in the regulation of emotional behavior in rodents

Effects of CCK-8 receptor agonists caerulein and pentagastrin and CCK-8 receptor antagonist proglumide on exploratory and locomotor activity of mice and rats were studied. Systemic administration of caerulein (500 ng/kg 1 mcg/kg) decreased significantly the exploratory activity of mice in elevated plus-maze. This anxiogenic-like action of caerulein was attenuated by acute pretreatment with proglumide (1 and 15 mg/kg) but not with diazepam (up to 0.75 mg/kg). Proglumide slightly increased the exploratory activity of rats in plus-maze; on the other hand, caerulein and pentagastrin potently decreased the measures of exploration in this test. Caerulein (10-100 mcg/kg) and proglumide (1 and 15 mg/kg) inhibited 3H-pentagastrin binding in mice brain in in vivo experiments. The data obtained indicate that CCK-8-ergic mechanisms in brain play an important role in the generation of anxiety states in rodents.     

Genetic evidence that cocaine and caffeine stimulate locomotion in mice via different mechanisms

The effects of cocaine and caffeine on motor activity in two mouse strains 129/OlaHsd (129) and C57BL/6J (C57) were compared. The former mice exhibited lower basal motor activity than the latter. Cocaine (3, 10, 30 mg/kg) injected i.p. in habituated C57 mice produced a dose-dependent increase in rearing, motility and locomotion. In 129 mice, little or no stimulation was seen and only with the highest dose of cocaine. In both strains caffeine (3, 15, 30 mg/kg) produced a dose-dependent increase in rearing, motility and locomotion. The effect of caffeine on rearing was greater in C57 than in 129 mice, but motility and locomotion were stimulated approximately to the same degree in both strains. Thus, differences in the sensitivity to caffeine and cocaine between mouse strains provide genetic evidence that these two stimulants probably produce locomotor stimulation via somewhat different mechanisms.     

Caffeine tolerance: behavioral, electrophysiological and neurochemical evidence

The development of tolerance to the stimulatory action of caffeine upon mesencephalic reticular neurons and upon spontaneous locomotor activity was evaluated in rats after two weeks of chronic exposure to low doses of caffeine (5-10 mg/kg/day via their drinking water). These doses are achievable through dietary intake of caffeine-containing beverages in man. Concomitant measurement of [3H]-CHA binding in the mesencephalic reticular formation was also carried out in order to explore the neurochemical basis of the development of tolerance. Caffeine, 2.5 mg/kg i.v., markedly increased the firing rate of reticular neurons in caffeine naive rats but failed to modify the neuronal activity in a group exposed chronically to low doses of caffeine. In addition, in spontaneous locomotor activity studies, our data show a distinct shift to the right of the caffeine dose-response curve in caffeine pretreated rats. These results clearly indicate that tolerance develops to the stimulatory action of caffeine upon the reticular formation at the single neuronal activity level as well as upon spontaneous locomotor activity. Furthermore, in chronically caffeine exposed rats, an increase in the number of binding sites for [3H]-CHA was observed in reticular formation membranes without any change in receptor affinity. We propose, therefore, that up-regulation of adenosine receptors may underlie the development of tolerance to the CNS effects of caffeine.     

Caffeine potentiates the enhancement by choline of striatal acetylcholine release.

We investigated the effect of peripherally administered caffeine (50 mg/kg), choline (30, 60, or 120 mg/kg) or combinations of both drugs on the spontaneous release of acetylcholine (ACh) from the corpus striatum of anesthetized rats using in vivo microdialysis. Caffeine alone or choline in the 30 or 60 mg/kg dose failed to increase ACh in microdialysis samples; the 120 mg/kg choline dose significantly enhanced ACh during the 80 min following drug administration. Coadministration of caffeine with choline significantly increased ACh release after each of the choline doses tested. Peak microdialysate levels with the 120 mg/kg dose were increased 112% when caffeine was additionally administered, as compared with 54% without caffeine. These results indicate that choline administration can enhance spontaneous ACh release from neurons, and that caffeine, a drug known to block adenosine receptors on these neurons, can amplify the choline effect.     

Pharmacological activity of the essential oil of Satureja viminea (Lamiaceae)

The aqueous extract and the essential oil of Satureja viminea (Lamiaceae) were tested. General physiologic effects were assessed through the Hippocratic screening test. Non fasted female Sprague Dawley rats were utilized and 250, 500, 750 and 1000 mg/kg doses were used. Two animals were used for each dosage level and for the vehicle alone. Exploratory behavior and curiosity were measured using a hole board apparatus and placing non-trained mice on the board and recording the number of holes explored in a 5 minute period. The Boissier chimney test was used to evaluate motor coordination. Muscle strength was assessed through a grasping test where mice were hung by their fore-limbs 40 cm above the base on a horizontal metal stainless bar. In all these tests, 3 groups of 6 albino mice, were treated with 1000 mg/kg of each the essential oil of S. viminea, the vehicle and diazepan (1 mg/kg) as a positive control. Analgesic activity was explored in Sprague-Dawley rats. The tail flick method described by D'Amour and Smith (1941) modified by CYTED was implemented on three groups (6 rats each) of animals treated with, each the essential oil of S. viminea (1000 mg/kg), the vehicle and indomethacine. The test was carried out just before and 30, 60 and 120 min after oral treatment. Peristaltic activity was measured in albino mice, three groups of 6 animals each, treated orally with each the essential oil of S. viminea (1000 mg/kg), the aqueous extract (1000 mg/kg), and the vehicle. The marker used was activated carbon. Animals were sacrificed 30 min after the marker was given and the percent of total small intestine traversed by it was calculated. Also a lethal dose 50 (LD 50) was determined with the Spearman-Karber method. A dose-related spontaneous motor activity reduction was observed. Exploratory behavior and curiosity were diminished. The grasping strength of mice was reduced. A very clear and significant analgesic effect was observed with the oral administration of the essential oil of S. viminea (1000 mg/kg). This effect is compared to that of indomethacine. Intestinal transit and gastric emptying were inhibited by the essential oil. The LD50 of the essential oil of S. viminea is 556.8 mg/kg.     

The dehydroepiandrosterone sulfate influence on anxiety and depressive behaviour: participation of mu-opioid receptors

The dehydroepiandrosterone sulfate (DHEAS) influence on anxiety and depressive behaviour was studied in animals after chronic stress exposures. It is shown that DHEAS (30 mg/kg) reduced anxiety in submission (with increased level of stress-induced anxiety resulting from chronic (20-days) defeats in aggressive interactions) of male mice of CBA/Lac strain in the "partition" test and in the plus-maze test, whereas in the control--only in the plus-maze test. DHEAS injection (30 mg/kg) in male Wistar rats decreased depressive behaviour in the Porsolt test in control and multiple (shuttling on the laboratory scrambler for 18 days by 1 hour in day) stressed animals. NaItrexone (0.25 mg/kg in mice and 0.1 mg/kg in rats) blocked anxiolytic and antidepressant-like effects of DHEAS. The findings suggest that these DHEAS effects are mediated by mu-opioid receptors.     

Modulation of anxiety-related behaviors by mu- and kappa-opioid receptor agonists depends on the social status of mice

This study was aimed to determine the effects of mu- and kappa-opioid receptor activation in relation to the social status of mice, being a winner with repeated experience of victories or a loser with repeated experience of social defeats. The behaviors of the animals were assessed in a social encounter test measuring the communicative behavior towards a familiar and an unfamiliar partner behind a perforated transparent partition (partition test) and in an elevated plus-maze test estimating the anxiety level of mice. Placebo and graded doses of the mu-opioid receptor agonist DAMGO (0.5 and 2 mg/kg s.c.) and the kappa-opioid receptor agonist U-50,488H (0.6, 1.25, and 2.5 mg/kg s.c.) were administered to the control mice, winners and losers in two experiments. In the partition test, the winners spent somewhat more time and the losers less time than the controls in the vicinity of their partner probably related to a lower and higher level of anxiety respectively. In the plus-maze test the losers appeared to have a somewhat higher anxiety level than the controls and winners. In both tests DAMGO produced anxiogenic-like effects in the winners and the controls, but not in the losers. Winners hardly responded to treatment with U-50,488H, while the losers responded dose dependently with an anxiolytic-like effect in both tests. It is concluded that anxiety-like responses in mice are differentially affected by stimulation of mu- and kappa-opioid receptors and that the effects depend on the social status of the animals.     

Anxiolytic effects of Equisetum arvense Linn. extracts in mice

The petroleum ether (PE), chloroform (CH), ethanol (ETH) and water extracts of E. arvense stems were evaluated for anti-anxiety activity in mice using elevated plus maze model. Ketamine induced hypnosis and actophotometer was used to evaluate sedative effect with various extracts in mice. The results were compared with standard drug diazepam. The ethanolic extract of E. arvense (50 and 100 mg/kg) significantly increased the time-spent and the percentage of the open arm entries in the elevated plus-maze model which was comparable to diazepam. Ethanolic extract (100 mg/kg) prolonged the ketamine-induced total sleeping time and decreased the locomotor activity in mice. The results suggest that the ethanolic extract of E. arvense seems to possess anxiolytic effect with lower sedative activity than that of diazepam. The results could be attributed to the flavonoid content of the ethanolic extract.     

Chronic effects of platinum(IV) complex and its diamine ligand on rat heart function: comparison with cisplatin

Mitochondrial dysfunction plays crucial role in the pathologenesis of myocardial infarction (MI). The present study evaluated the protective effect of α-bisabolol against isoproterenol (ISO)-induced mitochondrial dysfunction and apoptosis in rats. Male albino Wistar rats were pre- and co-treated with intraperitoneal injection of α-bisabolol (25 mg/kg body weight) daily for 10 days. To induce experimental MI, ISO (85 mg/kg body weight) was injected subcutaneously to the rats at an interval of 24 h for 2 days (9th and 10th day). ISO-induced MI was indicated by the decreased activities of heart creatine kinase and lactate dehydrogenase in rats. ISO administration also enhanced the concentrations of heart mitochondrial lipid peroxidation products and decreased the activities/concentrations of mitochondrial antioxidants, Kreb’s cycle dehydrogenases and mitochondrial electron transport chain complexes I, II?+?III and IV in rats. Furthermore, ISO triggers calcium overload and ATP depletion in the rat’s heart mitochondria followed by the mitochondrial cytochrome-C release and the activation of intrinsic pathway of apoptosis by upregulating the myocardial pro-apoptotic Bax, P⁵³, APAF-1, active caspase-3, active caspase-9 and down regulating the expressions of anti-apoptotic Bcl-2. α-Bisabolol pre and co-treatment showed considerable protective effects on all the biochemical and molecular parameters studied. Transmission electron microscopic study and mitochondrial swelling assay confirmed our biochemical and molecular findings. The in vitro study on hydroxyl radical also revealed the potent free radical scavenging activity of α-bisabolol. Thus, α-bisabolol attenuates mitochondrial dysfunction and intrinsic pathway of apoptosis in ISO-induced myocardial infarcted rats.

     

Effect of chronically administered methylxanthines on ethanol-induced motor incoordination in mice

The effect of chronic (10 days) administration of methylxanthines, caffeine, IBMX and theophylline on acute ethanol-induced motor incoordination has been investigated in the mice. In animals that received caffeine, 45 and 90 mg/kg/24 h, ethanol, 1.5 g/kg, produced motor incoordination significantly greater compared to that in the control groups. Significantly greater ethanol-induced motor incoordination was seen in animals fed IBMX, 30 and 60 mg/kg/24 h, compared to controls. Ethanol-induced increased motor incoordination in caffeine and IBMX-fed animals was also associated with significantly greater 3H-R-PIA binding in whole brains compared to tap water controls indicating an increase in brain adenosine binding sites. However neither motor incoordination nor 3H-R-PIA binding was altered in theophylline 75 and 150 mg/kg/24 h, fed animals. The increased motor incoordination associated with increased adenosine binding sites in the brains of caffeine and IBMX-fed animals suggests an involvement of central adenosine mechanisms in the motor incoordinating effect of ethanol and further supports our earlier suggestion for the role of adenosine in some of the central effects of ethanol.     

Anxiolytic effect of berberine on exploratory activity of the mouse in two experimental anxiety models: interaction with drugs acting at 5-HT receptors

The aim of this study was to assess the anxiolytic effect of berberine (abbrev. BER) using two experimental anxiety models in the mouse. In the black and white test of anxiety, berberine (100, 500 mg/kg) produced an increase in the first time entry, time spent in the white section, and total changes between two compartments. On the other hand, in the elevated plus-maze test, berberine (100, 500 mg/kg) produced an increase in the time spent and arm entries in the open arms, and a decrease in the time spent and arm entries in the closed arms. Berberine (500 mg/kg) decreased locomotor activity in mice. Furthermore, BER at 100, 500 mg/kg decreased concentrations of NE, DA and 5-HT, and increased the concentrations of VMA, HVA and 5-HIAA in the brain stem. BER also attenuated the anxiogenic effect of WAY-100635, 8-OH DPAT and DOI and enhanced the anxiolytic effect of BUS, p-MPPI and RIT in the elevated plus-maze. These results suggested that berberine at 100 mg/kg had a significant anxiolytic-like effect, which was similar to that observed with 1 mg/kg diazepam and 2 mg/kg buspirone. The anxiolytic mechanism of BER might be related to the increase in turnover rates of monoamines in the brain stem and decreased serotonergic system activity. Moreover, BER decreased serotonergic system activity via activation of somatodendritic 5-HT1A autoreceptors and inhibition of postsynaptic 5-HT1A and 5-HT2 receptors.