RESUMO
AIM: The inhalation of Lavandula angustifolia (lavender) essential oil has anxiolytic-like effects in animal models and humans, but its mechanism of action is still not fully understood. The inhalation of essential oils can induce anxiolytic effects through the central nervous system (e.g., lung absorption and bloodstream transport) or stimulation of the olfactory system and secondary activation of brain regions. Thus, the main objective of the present study was to evaluate whether the perception of lavender essential oil aroma, when inhaled, is necessary to obtain its anxiolytic-like effects in mice tested in the marble-burying test. MAIN METHODS: Anosmia was induced by irrigating the nasal cavity with zinc gluconate+zinc acetate so that the mice could not detect odors in the olfactory discrimination test. The marble-burying test was used to evaluate the anxiolytic-like effects of inhaled lavender essential oil. KEY FINDINGS: Anosmia did not interfere with the anxiolytic-like effect of lavender essential oil inhalation in the marble-burying test at concentrations of 2.5% (number of marbles buried: vehicle, 4.7±1.0; zinc, 6.2±2.2; p>0.10) and 5% (number of marbles buried: vehicle, 3.4±0.8; zinc, 4.3±0.9; p>0.10). Lavender essential oil at a concentration of 0.5% was ineffective. SIGNIFICANCE: These results suggest that olfactory system activation is unlikely to participate in the anxiolytic-like effect of lavender essential oil inhalation.
Assuntos
Ansiolíticos/farmacologia , Óleos Voláteis/farmacologia , Transtornos do Olfato/fisiopatologia , Óleos de Plantas/farmacologia , Administração por Inalação , Análise de Variância , Animais , Ansiolíticos/administração & dosagem , Comportamento Animal/efeitos dos fármacos , Diazepam/farmacologia , Lavandula , Masculino , Camundongos , Óleos Voláteis/administração & dosagem , Óleos de Plantas/administração & dosagemRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Lavandula angustifolia (lavender) inhalation has been used in folk medicine for the treatment of anxiety, and clinical and animal studies have corroborated its anxiolytic effect, although its mechanism of action is still not fully understood. AIMS OF THE STUDY: The objective of the present study was to determine whether the GABAA/benzodiazepine complex or serotonin neurotransmission mediates the anxiolytic-like effect of lavender essential oil. MATERIALS AND METHODS: Male Swiss mice were subjected to the marble-burying test after being exposed to the aroma of lavender essential oil (1-5%), amyl acetate (5%; used as a behaviorally neutral odor), or distilled water for 15 min via inhalation. Additionally, the effect of 5% lavender essential oil was also evaluated in mice subjected to the elevated plus maze. GABAA/benzodiazepine mediation was evaluated by pretreating the mice with the GABAA receptor antagonist picrotoxin before the marble burying test and [(3)H]flunitrazepam binding to the benzodiazepine site on the GABAA receptor. Serotonergic mediation was studied by pretreating the mice with O-methyl-[3H]-N-(2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl)-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride (WAY100635), a serotonin 5-HT1A receptor antagonist before the marble burying test. We also evaluated changes in the pharmacologically induced serotonin syndrome and the effects of combined administration of subeffective doses of lavender essential oil and the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). RESULTS: Lavender essential oil (1-5%) decreased the number of marbles buried compared with the control and amyl acetate groups. In the elevated plus maze, 5% lavender essential oil inhalation increased the percentage of time spent on and number of entries into the open arms compared with controls. No effect was seen in the number of closed arm entries or number of beam interruptions in the automated activity chamber. Pretreatment with the GABAA receptor antagonist picrotoxin (0.5mg/kg) did not modify the behavioral effect of 5% lavender essential oil in the marble-burying test. Lavender essential oil also did not alter [(3)H]flunitrazepam binding to the benzodiazepine site on the GABAA receptor. Pretreatment with the serotonin 5-HT1A receptor antagonist WAY100635 (3mg/kg) blocked the anxiolytic-like effect of lavender essential oil and the 5-HT1A receptor agonist 8-OH-DPAT (3mg/kg). A combination of ineffective doses of 8-OH-DPAT (0.5mg/kg) and lavender essential oil (0.1%) reduced the number of marbles buried. Finally, 5% lavender essential oil attenuated the serotonin syndrome induced by 40 mg/kg fluoxetine plus 80 mg/kg 5-hydroxytryptophan. CONCLUSIONS: These results indicate an important role for the serotonergic system in the anxiolytic-like effect of lavender essential oil.
Assuntos
Ansiolíticos/administração & dosagem , Óleos Voláteis/administração & dosagem , Óleos de Plantas/administração & dosagem , 8-Hidroxi-2-(di-n-propilamino)tetralina/farmacologia , Administração por Inalação , Animais , Comportamento Animal/efeitos dos fármacos , Encéfalo/metabolismo , Diazepam/metabolismo , Flunitrazepam/metabolismo , Antagonistas de Receptores de GABA-A/farmacologia , Lavandula , Masculino , Camundongos , Atividade Motora/efeitos dos fármacos , Picrotoxina/farmacologia , Piperazinas/farmacologia , Piridinas/farmacologia , Ratos , Receptores de GABA-A/metabolismo , Antagonistas da Serotonina/farmacologia , Agonistas do Receptor de Serotonina/farmacologia , Síndrome da Serotonina , Transmissão SinápticaRESUMO
The bilateral intranigral infusion of 1 micromol 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in adult male Wistar rats caused a specific and partial loss of substantia nigra pars compacta (SNc) dopamine neurons, a partial depletion of striatal dopamine, and a deficit to learn the intra-maze cued version of the Morris water maze. Pre-training the SNc rats in the spatial version of the water maze or simply maintaining the animals on the water maze platform reversed this deficit. This improvement was even observed when the order of the extra-maze cues presented to the rats during pre-training of the spatial version was changed during training of the intra-maze cued version. However, this deficit was not reversed either by maintaining the animals on the platform if the spatial cues were surrounded and covered with a curtain or by swimming sessions in the maze without the escape platform and the curtain. These findings suggest that none of the following elements alone, learned during the spatial task pre-training, could help SNc rats learn the intra-maze cued task: improvement of swimming skills or knowledge of the existence of the escape platform; distance between the platform and the border of the pool; location of a particular extra-maze cue; relations among extra-maze cues. However, the simultaneous presence of the escape platform and extra-maze cues (irrespective of their relational configuration) during the pre-training sessions proved to be necessary for this improving effect to occur.
Assuntos
Aprendizagem por Discriminação/fisiologia , Aprendizagem em Labirinto/fisiologia , Transtornos Parkinsonianos/fisiopatologia , Prática Psicológica , Substância Negra/metabolismo , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina , Adaptação Fisiológica , Análise de Variância , Animais , Sinais (Psicologia) , Modelos Animais de Doenças , Dopamina/metabolismo , Dopaminérgicos , Reação de Fuga , Masculino , Neostriado/metabolismo , Neostriado/fisiopatologia , Transtornos Parkinsonianos/induzido quimicamente , Ratos , Ratos Wistar , Comportamento Espacial/fisiologia , Estatísticas não Paramétricas , Substância Negra/efeitos dos fármacosRESUMO
Previous studies from our laboratory have shown that insect hunting is associated with a distinct Fos up-regulation in the ventrolateral caudoputamen at intermediate rostro-caudal levels. It is largely known that ventrolateral striatum participates in the control of orofacial movements and forepaw usage accompanying feeding behavior, but there has been no study investigating its possible roles during predatory hunting. We have presently examined the role of the ventrolateral striatum during roach hunting by using the reversible blockade with lidocaine. Accordingly, non-treated and saline-treated animals performed the insect hunting quite well, displaying a rather stereotyped form of motor actions for chasing, capturing and killing the prey. During the bilateral blockade of the ventrolateral striatum, the animals showed a significantly longer latency to start hunting and to capture the first prey. The lidocaine-treated animals captured the prey by using mostly the mouth, with little forepaw assistance, and were less effective in capturing the roaches. Moreover, while handling the prey, animals with ventrolateral striatal inactivation kept biting several parts of the prey, but failed to deliver the killing bite to the head, leaving them alive and moving, more likely to escape. Overall, the present findings suggest that the ventrolateral striatum implements the stereotyped actions seen during prey capture and handling, and may influence the motivational drive to start attacking the roaches, as well.
Assuntos
Corpo Estriado/fisiologia , Comportamento Predatório/fisiologia , Anestésicos Locais/farmacologia , Animais , Comportamento Animal/fisiologia , Corpo Estriado/efeitos dos fármacos , Privação de Alimentos , Lidocaína/farmacologia , Masculino , Comportamento Predatório/efeitos dos fármacos , Ratos , Ratos Wistar , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologiaRESUMO
The substantia nigra pars compacta (SNc) and the dorsal striatum are often considered to be necessary for stimulus-response (S-R) habit learning, whereas the dorsal hippocampus is considered to be necessary for relational (declarative) memory. Spatial learning is a kind of relational learning that occurs when a rat is released from different locations (variable start) in a water maze to find a submerged platform that is kept in a constant location. However, when the rat is always released from the same starting position (constant start), it can learn to find the platform oriented by a fixed configuration of cues, that is, by S-R learning. To test the critical role of the SNc in S-R and relational learning, the authors tested adult male Wistar rats, sham-operated or with a lesion in the SNc, in these 2 versions of the water maze task. The SNc lesion was induced by bilateral intranigral infusion of 0.5 micromol 1-methyl-4-phenyl- 1,2,3,6-tetrahydropyridine. Although the SNc-lesioned rats learned the variable-start version as effectively as sham rats did, they were significantly impaired in learning the constant-start version of the task.
Assuntos
Aprendizagem em Labirinto/fisiologia , Comportamento Espacial/fisiologia , Substância Negra/fisiopatologia , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Análise de Variância , Animais , Comportamento Animal , Monoaminas Biogênicas/metabolismo , Imuno-Histoquímica/métodos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Neurotoxinas/farmacologia , Ratos , Ratos Wistar , Tempo de Reação/efeitos dos fármacos , Comportamento Espacial/efeitos dos fármacos , Substância Negra/lesões , Natação , Fatores de TempoRESUMO
UNLABELLED: Dysraphism is a defect in neural tube development, leading to dysplastic growth of the spinal cord and meninges. Myelomeningocele (MM) is just one of its forms. Hydrocephalus is among the most important alterations in MM and occurs as a consequence of Arnold-Chiari malformation (AC). Experimental models have been developed in sheep, rabbits and rats to study MM physiopathology, allowing a more detailed evaluation of clinical parameters involved in this anomaly. OBJECTIVE: Using the experimental model of dysraphism in fetal rats, the aim of this study was to evaluate the relevance of AC malformations, clinical parameters and grade of histological lesions. MATERIALS AND METHODS: Three groups with 16 fetuses in each were compared, MM, Control and Sham, after intrauterine surgical creation of MM on day 18.5 of gestation (term = 22 days). AC was evaluated by photographic comparison of sagittal cuts of fetal heads. Clinical and histological evaluations were also made. RESULTS: 88% of AC (14/16) in MM fetuses were obtained, besides 100% of clinical alterations. Necrosis and erosion of the spinal cord exposed to amniotic fluid were verified in histology. CONCLUSION: The presence of AC in the dysraphism rat model was high. These results allowed the use of this model to study alterations and intrauterine evolution of MM in a fashion similar to those observed in humans.