Piracetam-induced changes on the brainstem auditory response in anesthetized juvenile rhesus monkeys (Macaca mulatta). Report of two clinical cases.

BACKGROUND: We describe two clinical cases and examine the effects of piracetam on the brainstem auditory response in infantile female rhesus monkeys (Macaca mulatta). RESULTS: We found that the interwave intervals show a greater reduction in a 3-year-old rhesus monkey compared to a 1-year-old rhesus monkey. DISCUSSION: In this report, we discuss the significance of these observations.

The selective inhibition of the D1 dopamine receptor results in an increase of metabolized dopamine in the rat striatum.

Our aim was to study the specific role of the postsynaptic D(1) receptors on dopaminergic response and analyze the metabolized dopamine (DA) in the rat striatum. We used male Wistar rats to evaluate the effects of different doses of a D(1) agonist (SKF-38393) and a D(1) antagonist (SCH-23390), and their co-administration. The levels of DA and L-3, 4-dihydroxyphenylacetic acid (DOPAC) were measured using high performance liquid chromatography. The systemic injection of SKF-38393 alone at 1, 5 and 10 mg/kg did not alter the DA and DOPAC levels or the DOPAC/DA ratio. In contrast, injection of SCH-23390 alone at 0.25, 0.5 and 1 mg/kg significantly increased the DA and DOPAC levels, as well as the DOPAC/DA ratio, compared with the respective control groups. The co-administration of SCH-23390+SKF-38393 did not alter the DA or DOPAC levels, but it did significantly inhibit the SCH-23390-induced increase of the DA and DOPAC levels. The SCH-23390+SKF-38393 and the SCH-23390-only groups showed an increase in the DOPAC/DA ratio. The co-administration of SCH-23390+PARGYLINE significantly decreased the DOPAC levels and the DOPAC/DA ratio compared with the control and SCH-23390 groups. Taken together, our results showed that selective inhibition with SCH-23390 produced an increase in metabolized DA via striatal monoamine oxidase. These findings also contribute to the understanding of the role of postsynaptic D(1) receptors in the long-loop negative feedback system in the rat striatum.

[Paradigm of negative feedback via long-loop in the striatal dopamine release modulation in the rat]. / Paradigma de retroalimentacion negativa via circuito largo en la modulacion de la liberacion de dopamina en el estriado dorsal de la rata.

INTRODUCTION: The basal ganglia include the striatum, globus pallidus, the substantia nigra pars compacta and pars reticulata. The striatum receives afferent input from the substantia nigra pars compacta. The principal neurons of the striatum are medium spiny neurons, that express high levels of D1 and D2 receptors. AIMS: This review deals about the aspects underlying to the negative feedback via long-loop in the striatal dopamine release modulation in the rat. Also, the motor function in dopamine receptor knock-out mice is discussed. DEVELOPMENT AND CONCLUSIONS: The intrastriatal infusion and systemic injection of dopamine receptor agonists and antagonists may regulate the striatal dopamine release and induce changes in motor function. Disruption of the D1 and D2 gene shown that the motor function is controlled by D1 and D2 receptors. The study of the long-loop negative feedback may contribute to our understanding in the physiology and dysfunction of basal ganglia.

[Evaluation of the motor behavior in rats with cortical ablation]. / Caracterizacion de la conducta motora en ratas con ablacion cortical.

INTRODUCTION: The cortical ablation has been used as an experimental model in order to study the basic mechanisms of functional recovery. However, there is not data concerning to the injury effects on the motor and somatosensorial behavioral manifestations that allow us to categorize such sequels as a hemiplegic model. MATERIALS AND METHODS: We used 35 male Wistar rats (280-300 g) allocated in two groups: control (n = 17) and brain injured by cortical ablation (n = 18). Previously trained, basal recordings of the footprint and motor and somatosensorial assessment were performed in the rats before surgery. The behavioral tests were performed again 6 hours after surgery and the spontaneous ambulatory activity was also evaluated. RESULTS AND CONCLUSIONS: It was observed a decrease in the stride's length and an increase in the stride's angle and in the motor deficit, while the somatosensorial assessment and spontaneous ambulatory activity were not affected. These findings are discussed in function of the motor features of the hemiparetic sequels in humans.

Caracterización de la conducta motora en ratas con ablación cortical / Evaluation of the motor behavior in rats with cortical ablation

Introducción. El modelo de ablación cortical en ratas se ha utilizado para estudiar los mecanismos básicos de recuperación funcional, pero no hay datos respecto a los efectos de la lesión sobre las manifestaciones conductuales motoras y somatosensoriales que permitan categorizar estas secuelas como un modelo de hemiplejía. Materiales y métodos. Se utilizaron 35 ratas machos Wistar (280-300 g), distribuidas en dos grupos: control (n = 17) y con lesión cerebral por ablación cortical(n = 18). Previo entrenamiento, se tomaron registros de la impresión de la huella y de las evaluaciones motora y somatosensorial antes de la cirugía de lesión. Seis horas después de la lesión se realizaron nuevamente las pruebas conductuales y se registró la actividad ambulatoria espontánea. Resultados y conclusiones. Se encontró que la lesión disminuye la longitud e incrementa el ángulo de la zancada y el déficit motor, sin afectar los aspectos somatosensoriales ni la actividad ambulatoriaespontánea. Estos hallazgos se discuten en función de las características motoras de las secuelas hemiparéticas comunicadas en humanos

Introduction. The cortical ablation has been used as an experimental model in order to study the basic mechanismsof functional recovery. However, there is not data concerning to the injury effects on the motor and somatosensorial behavioral manifestations that allow us to categorize such sequels as a hemiplegic model. Materials and methods. We used 35 male Wistarrats (280-300 g) allocated in two groups: control (n = 17) and brain injured by cortical ablation (n = 18). Previously trained, basal recordings of the footprint and motor and somatosensorial assessment were performed in the rats before surgery. The behavioral tests were performed again 6 hours after surgery and the spontaneous ambulatory activity was also evaluated.Results and conclusions. It was observed a decrease in the stride’s length and an increase in the stride’s angle and in the motor deficit, while the somatosensorial assessment and spontaneous ambulatory activity were not affected. These findings arediscussed in function of the motor features of the hemiparetic sequels in humans