The alteration of neuronal activities of the cuneiform nucleus in non-hypovolemic and hypovolemic hypotensive conditions.

BACKGROUND: The cuneiform nucleus is located in the center of the circuit that mediates autonomic responses to stress. Hemorrhagic hypotension leads to chemoreceptor anoxia, which consequently results in the reduction of baroreceptor discharge and stimulation of the chemoreceptor. OBJECTIVE: Using the single-unit recording technique, the neuronal activities of the cuneiform nucleus were investigated in hypotensive states induced by hemorrhage and administration of an anti-hypertensive drug (hydralazine). METHODS: Thirty male rats were divided into the control, hemorrhage, and hydralazine groups. The femoral artery was cannulated for the recording of cardiovascular responses, including systolic blood pressure, mean arterial pressure, and heart rate. Hydralazine was administered via tail vein. The single-unit recording was performed from the cuneiform nucleus. RESULTS: The maximal systolic blood pressure and the mean arterial pressure significantly decreased and heart rate significantly increased after the application of hydralazine as well as the following hemorrhage compared to the control group. Hypotension significantly increased the firing rate of the cuneiform nucleus in both the hemorrhage and hydralazine groups compared to the control group. CONCLUSIONS: The present data indicate that the cuneiform nucleus activities following hypotension may play a crucial role in blood vessels and vasomotor tone.

The alteration of neuronal activities of the cuneiform nucleus in non-hypovolemic and hypovolemic hypotensive conditions / Alterações da atividade neuronal no núcleo cuneiforme em condições hipovolêmicas e não hipovolêmicas

Abstract Background: The cuneiform nucleus is located in the center of the circuit that mediates autonomic responses to stress. Hemorrhagic hypotension leads to chemoreceptor anoxia, which consequently results in the reduction of baroreceptor discharge and stimulation of the chemoreceptor. Objective: Using the single-unit recording technique, the neuronal activities of the cuneiform nucleus were investigated in hypotensive states induced by hemorrhage and administration of an anti-hypertensive drug (hydralazine). Methods: Thirty male rats were divided into the control, hemorrhage, and hydralazine groups. The femoral artery was cannulated for the recording of cardiovascular responses, including systolic blood pressure, mean arterial pressure, and heart rate. Hydralazine was administered via tail vein. The single-unit recording was performed from the cuneiform nucleus. Results: The maximal systolic blood pressure and the mean arterial pressure significantly decreased and heart rate significantly increased after the application of hydralazine as well as the following hemorrhage compared to the control group. Hypotension significantly increased the firing rate of the cuneiform nucleus in both the hemorrhage and hydralazine groups compared to the control group. Conclusions: The present data indicate that the cuneiform nucleus activities following hypotension may play a crucial role in blood vessels and vasomotor tone.

RESUMO Antecedentes: O núcleo cuneiforme está localizado no centro do circuito que media as respostas autonômicas ao estresse. A hipotensão hemorrágica leva à anóxia dos quimiorreceptores, que, consequentemente, resulta na redução da descarga dos barorreceptores e estimulação do quimiorreceptor. Objetivo: Utilizando a técnica de registro em unidade única, as atividades neuronais do núcleo cuneiforme foram investigadas em estados de hipotensão induzida por hemorragia e administração de um anti-hipertensivo (hidralazina). Métodos: Trinta ratos machos foram divididos nos grupos controle, hemorragia e hidralazina. A artéria femoral foi canulada, para o registro de respostas cardiovasculares, incluindo pressão arterial sistólica, pressão arterial média e frequência cardíaca. A hidralazina foi administrada na veia da cauda. O registro de unidade única foi realizado a partir do núcleo cuneiforme. Resultados: A pressão arterial sistólica máxima e a pressão arterial média diminuíram significativamente, e a frequência cardíaca aumentou significativamente após a aplicação de hidralazina, bem como a hemorragia seguinte, em comparação com o grupo controle. A hipotensão aumentou significativamente a taxa de disparo da população do núcleo cuneiforme em ambos os grupos de hemorragia e hidralazina, em comparação com o grupo de controle. Conclusões: Os presentes dados indicam que as atividades do núcleo cuneiforme após hipotensão podem desempenhar um papel crucial nos vasos sanguíneos e no tônus vasomotor.

Hypnotic Activity of Capparis spinosa Hydro-alcoholic Extract in Mice.

BACKGROUND: Sleep disorders are among the most common psychiatric and medical conditions. Herbal medicine appears to be effective in the treatment of sleep disorders which have been valued by many of publications and patents. OBJECTIVE: The present study aimed at investigating the hypnotic activity of the hydro-alcoholic extract of Capparis spinosa (HAE) in mice. METHODS: Three doses of HAE (30, 60 and 120 mg/kg) and three fractions of it, namely n-hexane fraction (NHF), water fraction (WF), and ethyl acetate fraction (EAF), were given in comparison with diazepam (3 mg/kg body weight i.p.) as a positive control and saline as a negative control. After 30 min, pentobarbital (30 mg/kg body weight i.p.) was administered. In addition, LD50 of HAE was examined and the cytotoxicity of HAE was assessed in l929 cells using the MTT assay. Moreover, for motorcoordination ability, 30 mins after administration of HAE, the rotarod test was performed. RESULTS: The results exhibited that the HAE and all the fractions significantly augmented pentobarbital induced sleeping time, which was comparable to that of induced by diazepam. The LD50 value was 2.4 g/kg. The extract did not induce any cytotoxic effects in L929 fibroblast cells. HAE did not affect the animals' performance on the rotarod test. CONCLUSION: Our finding suggests that the hydro-alcoholic extract of C. spinosa possesses a hypnotic potential that may require further scientific investigations.

Cannabinoid type 1 receptor antagonism ameliorates harmaline-induced essential tremor in rat.

BACKGROUND AND PURPOSE: Essential tremor (ET) is a neurological disorder with unknown aetiology. Its symptoms include cerebellar motor disturbances, cognitive and personality changes, hearing and olfactory deficits. Hyperactivity of excitotoxic cerebellar climbing fibres may underlie essential tremor and has been induced in rodents by systemic harmaline administration. Cannabinoid (CB) receptor agonists can cause motor disturbances; although, there are also anecdotal reports of therapeutic benefits of cannabis in motor disorders. We set out to establish the effects of CB receptor agonism and antagonism on an established rodent model of ET using a battery of accepted behaviour assays in order to determine the risk and therapeutic potential of modulating the endocannabinoid system in ET. EXPERIMENTAL APPROACH: Behavioural effects of systemic treatment with a CB receptor agonist (0.1, 0.5 and 1 mg kg-1 WIN55, 212-2) or two CB1 receptor antagonists (1 mg kg-1  AM251 and 10 mg kg-1 rimonabant) on tremor induced in rats by harmaline (30 mg kg-1 ; i.p.), were assessed using tremor scoring, open field, rotarod, grip and gait tests. KEY RESULTS: Overall, harmaline induced robust tremor that was typically worsened across the measured behavioural domains by CB receptor agonism but ameliorated by CB1 receptor antagonism. CONCLUSIONS AND IMPLICATIONS: These results provide the first evidence of the effects of modulating the endocannabinoid system on motor function in the harmaline model of ET. Our data suggest that CB1 receptor manipulation warrants clinical investigation as a therapeutic approach to protection against behavioural disturbances associated with ET.

Cannabinoid receptor agonism suppresses tremor, cognition disturbances and anxiety-like behaviors in a rat model of essential tremor.

Cognitive and motor disturbances are serious consequences of tremor induced by motor disorders. Despite a lack of effective clinical treatment, some potential therapeutic agents have been used to alleviate the cognitive symptoms in the animal models of tremor. In the current study, the effects of WIN55, 212-2 (WIN), a cannabinoid receptor (CBR) agonist, on harmaline-induced motor and cognitive impairments were studied. Adult rats were treated with WIN (0.5mg/kg; i.p.) 15min before harmaline administration (10mg/kg; ip) after which exploratory and anxiety related behaviors, and cognitive function were assessed using open-field behavior and shuttle box tests. Rats that received harmaline only exhibited a markedly reduced number of central square entries when compared to harmaline vehicle-treated controls, whereas those treated with WIN and harmaline showed a significant increase in central square entries, compared to harmaline only treated. The passive avoidance memory impairments observed in harmaline treated rats, was reversed somewhat by administration of WIN. The neuroprotective and anxiolytic effects of WIN demonstrated in the current study can be offered cannabinoid receptor (CBR) agonism as a potential neuroprotective agent in the treatment of patients with tremor that manifest mental dysfunctions.

Cannabinoids and Tremor Induced by Motor-related Disorders: Friend or Foe?

Tremor arises from an involuntary, rhythmic muscle contraction/relaxation cycle and is a common disabling symptom of many motor-related diseases such as Parkinson disease, multiple sclerosis, Huntington disease, and forms of ataxia. In the wake of anecdotal, largely uncontrolled, observations claiming the amelioration of some symptoms among cannabis smokers, and the high density of cannabinoid receptors in the areas responsible for motor function, including basal ganglia and cerebellum, many researchers have pursued the question of whether cannabinoid-based compounds could be used therapeutically to alleviate tremor associated with central nervous system diseases. In this review, we focus on possible effects of cannabinoid-based medicines, in particular on Parkinsonian and multiple sclerosis-related tremors and the common probable molecular mechanisms. While, at present, inconclusive results have been obtained, future investigations should extend preclinical studies with different cannabinoids to controlled clinical trials to determine potential benefits in tremor.

The therapeutic potential of Berberine chloride hydrate against harmaline-induced motor impairments in a rat model of tremor.

Essential tremor (ET) is a progressive neurological disorder with motor and non-motor symptoms. It has conclusively been shown that modulation of glutamate receptors could ameliorate ET. Recent studies have suggested that Berberine (BBR) has an inhibitory effect on glutamate receptors. Therefore, BBR may have therapeutic effects on ET. In this study, male Wistar rats (n=10 in each group) weighing 40-60 g were divided into control, harmaline (30 mg/kg, i.p.) and berberine (10, 20 or 50mg/kg, i.p, 15 min before harmaline injection) groups. Open field, rotarod, wire grip and foot print tests were used to evaluate motor performance. The results indicated that the administration of BBR (10 and 20mg/kg) attenuated harmaline-induced tremor in rats, but the beneficial effects of BBR could not be identified at dose 50mg/kg. In addition, BBR ameliorated gait disturbance in doses of 10 and 20mg/kg. The high dose of BBR not only failed to recover step width but also showed an adverse effect on left and right step length. The results indicate that BBR only in dose of 20mg/kg recovers mobility duration. The current study found a dose-dependent manner for the therapeutic effects of BBR in ET. Our study provides the initial evidence for the effects of BBR on motor function. Since BBR exerts its effects mainly through regulation of neurotransmitter release or blocke of NMDA receptors, thus, it is predicted that BBR ameliorate harmaline effect through blockade of NMDA receptors or glutamate release. This is an important issue for future research to evaluate the possible mechanisms involved.