Vania Moraes Ferreira

Anxiolytic and antidepressant-like effects of Melissa officinalis (lemon balm) extract in rats: Influence of administration and gender

Objective: To analyse the behavioral effects of Melissa officinalis extract in rats following acute or subacute treatment. Materials and Methods: The behavioral effects of an acute or subacute (10-day course) orally administered M. officinalis (MO; 0, 30, 100 or 300 mg/kg) ethanol extract were evaluated in male and female Wistar rats in elevated plus-maze (EPM), forced swimming (FS) and open field (OF) tests. The effects of diazepam (DZP; 1 mg/kg) and fluoxetine (FXT; 10 mg/kg) were also assessed. Results: In the EPM test, the percentage of open arm entries and open arm times of both males and females given the subacute M. officinalis ethanol extract were significantly higher than those of the vehicle-treated animals but were at levels similar to those observed in the DZP group, regardless of the treatment length. In the FS test, immobility duration was significantly lower in both males and females treated with the plant extract when compared to vehicle-treated counterparts. A 10-day treatment with FXT induced the same antidepressant response, regardless of gender, and was more effective than the M. officinalis extract. Male and female rats demonstrated distinct gender profiles, and treatment × gender interactions were observed. Locomotion in the EPM and OF tests was not significantly altered by treatments. Conclusion: The potential psychoactive properties of M. officinalis may provide a unique pharmacological alternative for certain psychiatric disorders; however, the efficacy appears to be dependent on both gender and administration length.

Interference of ethanol and methylmercury in the developing central nervous system.

Studies involving alcohol and its interactions with other neurotoxicants represent the focus of several works of research due to the fact that the use of alcohol can sometimes leads to serious health problems. Fetal exposure to alcohol and mercury has a high incidence in some regions of Brazil, where there are pregnant women who are alcoholics and live in mining areas. This work was conducted to examine the effects of combined exposure to ethanol (EtOH) and methylmercury (MeHg) in rats during the development of the central nervous system (CNS). Experimental behavioral animal models/tests were used in order to examine locomotion, anxiety, depression and memory. Pregnant rats received tap water or EtOH 22.5% w/v (6.5 g/kg per day), by gavage) during pregnancy and breast-feeding. On the 15th day of pregnancy, some groups received 8 mg/kg of MeHg (by gavage). The groups were as follows: control, EtOH, MeHg and EtOH+MeHg. The experimental results showed that the EtOH, MeHg and EtOH+MeHg groups reduced the percentage of frequency and time spent in the open arms entries of the elevated plus-maze (EPM) test, when compared to the control group. This result suggests an anxiogenic behavioral response. The MeHg group increased locomotor activity in the arena and the immobility time in the forced swimming test, suggestive of depression-like behavior. The EtOH+MeHg group showed greater reductions in the percentages of frequency and time spent in the open arms entries in the EPM test, suggesting a sedative-behavior since the frequency of enclosed arm entries was affected. In the inhibitory avoidance task, the EtOH+MeHg group reduced the latency of the step-down response onto the grid floor, suggesting a cognitive and behavior dysfunctions. Taken together, the results suggest that EtOH and/or MeHg intoxication during the developing CNS may be a risk for deficits related to locomotor impairment, anxiety, depression and neurocognitive functions. There is a possibility that EtOH may prevent some of the MeHg responses, but the precise mechanism of action involved in this process needs to be considered for future research.

Inhibitory avoidance acquisition in adult rats exposed to a combination of ethanol and methylmercury during central nervous system development.

Previous studies have shown that combined exposure to ethanol (EtOH) and methylmercury (MeHg) in rats during central nervous system development produces several behavioural impairments. This present study was done to investigate inhibitory avoidance acquisition and panic-like disorders in rats in an elevated T-maze (ETM) model of anxiety. Pregnant rats received tap water or EtOH at 22.5% (w/v) (6.5 g/kg per day, by gavage) during pregnancy and lactation. On the 15th day of pregnancy, half of each group received MeHg (8 mg/kg, by gavage). Adult offspring intoxicated by both EtOH + MeHg showed an increase in the ETM re-exposure time. Upon analysis of the enclosed arms latency in baseline and avoidance 1 session it was observed that the rats spent less time inside the arm, suggesting impairment in their short-term memory. The escape latency decreased for EtOH + MeHg and also for EtOH and MeHg groups, suggesting panic-like behaviour. After 24-h and 7-day trials (tests and retests), MeHg and EtOH + MeHg groups had their latency in the enclosed arm reduced with the exception of the EtOH group, revealing memory impairment. Upon analysis of the risk assessment, animals treated with EtOH + MeHg were the only ones to show a decrease in all evaluation stages. This study demonstrates that the exposure to both EtOH and MeHg has an impact on memory and panic-related behaviours, leading to the assertion that this association of toxicants should be studied more in detail to clarify the precise mechanisms of these pharmacological effects.

Role of glutamate receptors and nitric oxide on the effects of glufosinate ammonium, an organophosphate pesticide, on in vivo dopamine release in rat striatum

The purpose of the present work was to assess the possible role of glutamatergic receptors and nitric oxide (NO) production on effects of glufosinate ammonium (GLA), an organophosphate pesticide structurally related to glutamate, on in vivo striatal dopamine release in awake and freely moving rats. For this, we used antagonists of NMDA (MK-801 and AP5) or AMPA/kainate (CNQX) receptors, or nitric oxide synthase (NOS) inhibitors (l-NAME and 7-NI), to study the effects of GLA on release of dopamine from rat striatum. So, intrastriatal infusion of 10mM GLA significantly increased dopamine levels (1035±140%, compared with basal levels) and administration of GLA to MK-801 (250μM) or AP5 (650μM) pretreated animals, produced increases in dopamine overflow that were ∼40% and ∼90% smaller than those observed in animals not pretreated with MK-801 or AP5. Administration of GLA to CNQX (500μM) pretreated animals produced an effect that was not significantly different from the one produced in animals not pretreated with CNQX. On the other hand, administration of GLA to l-NAME (100μM) or 7-NI (100μM) pretreated animals, produced increases in dopamine overflow that were ∼80% and ∼75% smaller than those observed in animals not pretreated with these inhibitors. In summary, GLA appears to act, at least in part, through an overstimulation of NMDA (and not AMPA/kainate) receptors with possible NO production to induce in vivo dopamine release. Administration of NMDA receptor antagonists and NOS inhibitors partially blocks the release of dopamine from rat striatum.

Ethanolic extract from bulbs of Cipura paludosa reduced long-lasting learning and memory deficits induced by prenatal methylmercury exposure in rats.

Previous studies from our group have indicated important biological properties of the ethanolic extract (EE) and isolated compounds from the bulbs of Cipura paludosa (Iridaceae), a native plant widely distributed in northern Brazil. In the present study, the effects of chronic treatment with the EE on the memory of adult rats exposed to methylmercury (MeHg) during early development were assessed. Pregnant rats were treated by gavage with a single dose of MeHg (8 mg/kg) on gestational day 15, the developmental stage critical for cortical neuron proliferation. Adult offspring were administered orally with the EE of C. paludosa (1, 10 or 100mg/kg) over 14 consecutive days. EE improved short-term social memory in a specific manner and facilitated the step-down inhibitory avoidance of short- and long-term memory. MeHg exposure induced pronounced long-lasting impairments in social recognition memory that were improved by EE. Moreover, EE significantly increased the step-down latencies specifically during the short-term session in prenatal MeHg-exposed rats. These results demonstrate that EE reduced the long-lasting short-term learning and memory deficits induced by MeHg exposure. These findings may encourage further studies evaluating the cognitive enhancing properties of C. paludosa and its components on neuropathological conditions associated with exposure to environmental contaminants.

A new naphthoquinone isolated from the bulbs of Cipura paludosa and pharmacological activity of two main constituents.

Cipura paludosa (Iridaceae) is a plant that is distributed in the north region of Brazil. Its bulbs are used in folk medicine to treat inflammation and pain. Four naphthalene derivatives have been isolated from the bulbs of this plant. Three of them have been identified as the known naphthalene derivatives, eleutherine, iso-eleutherine, and hongkonin. The structure of the fourth and new component was determined as 11-hydroxyeleutherine by extensive NMR study. In addition, the IN VIVO effect of the two major compounds, eleutherine and iso-eleutherine, was evaluated in carrageenan-induced hypernociception and inflammation in mice. Eleutherine and iso-eleutherine (1.04-34.92 µmol/kg), dosed intraperitoneally (i.p.) or orally (p.o.), decreased the carrageenan-induced paw oedema (i.p. - inhibitions of 36 ± 7 % and 58 ± 14 %, respectively; p.o. - inhibitions of 36 ± 7 % and 58 ± 14 %, respectively). Iso-eleutherine, but not eleutherine, significantly reduced (inhibitions of 39 ± 4 %) the plasma extravasation induced by intradermal (i.d.) injection of carrageenan. Likewise, eleutherine and iso-eleutherine (1.04-34.92 µmol/kg, i.p. or p.o.) were also effective in preventing the carrageenan-induced hypernociceptive response (i.p. - inhibition of 59 ± 4 % and 63 ± 1 %, respectively; p.o. - inhibitions of 36 ± 7 % and 58 ± 14 %, respectively). It was also suggested that the anti-inflammatory and anti-hypernociceptive effects of eleutherine or iso-eleutherine partly depend on the interference with the synthesis or activity of mast cell products, kinins, cytokine, chemokines, prostanoids, or sympathetic amines. Our findings show that two major compounds of C. paludosa contain pharmacologically active constituents that possess antinociceptive and anti-inflammatory activity, justifying, at least in part, its popular therapeutic use for treating conditions associated with pain.

Cipura paludosa attenuates long-term behavioral deficits in rats exposed to methylmercury during early development.

In the present study, we evaluated the effects of the ethanolic extract (EE) of Cipura paludosa on locomotor, and anxiety- and depression-like behaviors of adult rats exposed to MeHg during early development. Additionally, the antioxidant enzymes catalase (CAT) and selenium-glutathione peroxidase (Se-GPx) were measured in cortical, hippocampal, and cerebellar tissues. Pregnant Wistar rats were treated by gavage with a single dose of MeHg (8 mg/kg) on gestational day 15, the developmental stage critical for cortical neuron proliferation. Moreover, prenatal MeHg exposure inhibited CAT and Se-GPx in the cortex and cerebellum. Chronic treatment with the EE of C. paludosa attenuated these emotional and antioxidant deficits induced by prenatal MeHg toxic exposure. This study provides novel evidence that developmental exposure to MeHg can affect not only cognitive functions but also locomotor, and anxiety- and depression-like behaviors.

Role of nicotine on cognitive and behavioral deficits in sepsis-surviving rats.

Sepsis and its complications are important causes of mortality in intensive care units and sepsis survivors may present long-term cognitive and emotional impairments, including memory deficits and anxiety symptoms. In the present study, we investigated whether repeated nicotine administration can affect the behavioral changes in sepsis-surviving rats. Male Wistar rats were divided in two groups: sham-operated and experimental sepsis induced by cecal ligation and puncture (CLP). The animals were injected subcutaneously with nicotine (0.1 mg/kg) or vehicle once a day during 1 week before and/or 1 week after sepsis induction. Thirty minutes after the last administration (i.e., 7 days after surgery), the animals were tested in the open field, elevated plus-maze and step-down inhibitory avoidance tasks. The repeated nicotine treatment did not affect the survival rate in the sepsis group (50%). Moreover, no significant changes on locomotor activity were observed in the sepsis group while the treatment with nicotine during 1 week after surgery reduced the locomotion of sepsis-surviving rats in the open field. It is important to note that both schedules of nicotine treatment (prior and/or after CLP) improved the sepsis-induced anxiogenic-like responses. Interestingly, nicotine was able to improve short- and long-term inhibitory avoidance memory impairments, observed in sepsis survivors, only when administered during 2 consecutive weeks (i.e., prior and after CLP). Taken together, these results indicate that repeated nicotine administration does not alter the survival rate in rats submitted to CLP and provide new evidence that nicotine can improve long-lasting memory impairments and anxiogenic-like responses in sepsis-surviving animals.

Behavioural and cognitive effects of simvastatin dose used in stimulation of bone regeneration in rats

PURPOSE To analyze the effects of simvastatin (SVT) in the locomotion, anxiety and memory of rats, as a reflection of the administration of a minimum dose capable of stimulating bone regeneration in defects in the calvariae. METHODS Surgical procedures were performed in 15 female Wistar rats, 2-month old, to insert the grafting material regenerator (Bone-ceramic®) and/or SVT, followed by behavioural and cognitive assessments in the 7th, 30th and 60th days post surgery. RESULTS The SVT locally applied with the goal of bone regeneration in defects created in rat calvariae does not interfere with locomotion, anxiety levels and/or memories of rats, except for the first week following surgery, when an anxiolytic effect was observed, as a result of a possible central action. CONCLUSION Failure to provoke any response within 30 and 60 days post surgical procedures suggests that SVT may constitute a good choice in stimulating bone regeneration without affecting the long term neural functions.

Evaluation of antinociceptive and anti-inflammatory activities of the topical preparation of Cipura paludosa (Iridaceae)

Alho do mato (Cipura paludosa, Iridaceae) is a medicinal plant found in the Amazon rain forest, North of Brazil. It has been used to treat algic, inflammatory and infectious processes. The aim of this study was to evaluate the anti-inflammatory and antinociceptive action of the crude Cipura paludosa ethanolic extract at concentrations ranging between 2.0 and 4.0% in Oil and Water cream formulations for topical use. The physical-chemical stability of the formulations was monitored over a six-month period with the use of accelerated stability tests. In order to evaluate the anti-inflammatory and antinociceptive activities, we used a paw edema test induced by carrageenan and a formalin test, respectively. The paw edema test showed that there was a statistical difference in the control group in relation to the treatments. The formalin test did not confirm antinociceptive action of the treatments with the extract in the early phase of the test. However, statistical difference was confirmed for the treatments in relation to the control in the late phase. The antinociceptive and anti-inflammatory activities of Cipura paludosa preparations, as demonstrated in the results, at least partially support the ethno-medical uses of this plant.