Activación del cerebelo por estimulación olfativa en ratas macho sexualmente inexpertas / Activation of the cerebellum by olfactory stimulation in sexually naive male rats

Introducción: El cerebelo es una estructura que se ha vinculado con múltiples funciones, tales como control motor, cognición, memoria y procesamiento emocional. En cuanto a su relación con los sistemas sensoriales no está claro el papel que desempeña en relación con el sentido del olfato. Suponemos que las ratas macho sexualmente inexpertas presentarán un incremento en la actividad neuronal del vermis cerebelar tras ser estimuladas con olor de hembra receptiva y almendra. Métodos: Comparamos la actividad de la capa granular del vermis cerebelar mediante la inmunorreactividad a Fos tras estimulación olfativa. Esta estimulación se realizó durante 60 min en cámaras cúbicas de acrílico con un doble fondo. Los estímulos fueron aserrín limpio, con esencia de almendra y proveniente de la cama de hembras receptivas. Finalmente los machos fueron anestesiados con pentobarbital sódico intraperitoneal. El tejido cerebelar fue fijado con paraformaldehído para su posterior análisis inmunohistoquímico. Resultados: El número de células inmunorreactivas a Fos en todos los lóbulos del vermis cerebelar de los grupos estimulados con almendra y hembra receptiva fue similar, pero mayor comparado con el grupo de aserrín limpio. Conclusiones: La estimulación olfativa del sistema olfatorio principal (almendra) y accesorio (hembra receptiva) incrementa la producción de proteína Fos en la capa granular de la corteza cerebelar del vermis de ratas macho sexualmente inexpertas

Introduction: The cerebellum has been linked to multiple functions, such as motor control, cognition, memory, and emotional processing. As for its involvement in the sensory systems, the role of the cerebellum in the sense of smell remains unclear. We suggest that sexually naive male rats will present increased neuronal activity in the cerebellar vermis after being stimulated with almond odour or oestrous odour from receptive females. Methods: We compared activity in the cerebellar vermis using Fos immunoreactivity after olfactory stimulation. Stimulation took place during 60 min in a cube-shaped acrylic chamber with a double bottom. Stimuli were clean woodchip bedding, bedding with almond extract, and bedding taken from a cage of receptive females. Male rats were subsequently anaesthetised with intraperitoneal sodium pentobarbital. Cerebellar tissue was fixed with paraformaldehyde for later immunohistochemical analysis. Results: The number of Fos immunoreactive cells in all lobes of the cerebellar vermis was similar between groups stimulated with almond extract and with oestrous odour, and higher than in the clean woodchip group. Conclusions: Stimulation of the main olfactory system (almond) and the accessory system (oestrous odour) increases Fos protein production in the granular layer of the cortex of the cerebellar vermis in naive male rats

Activation of the cerebellum by olfactory stimulation in sexually naive male rats.

INTRODUCTION: The cerebellum has been linked to multiple functions, such as motor control, cognition, memory, and emotional processing. As for its involvement in the sensory systems, the role of the cerebellum in the sense of smell remains unclear. We suggest that sexually naive male rats will present increased neuronal activity in the cerebellar vermis after being stimulated with almond odour or oestrous odour from receptive females. METHODS: We compared activity in the cerebellar vermis using Fos immunoreactivity after olfactory stimulation. Stimulation took place during 60 min in a cube-shaped acrylic chamber with a double bottom. Stimuli were clean woodchip bedding, bedding with almond extract, and bedding taken from a cage of receptive females. Male rats were subsequently anaesthetised with intraperitoneal sodium pentobarbital. Cerebellar tissue was fixed with paraformaldehyde for later immunohistochemical analysis. RESULTS: The number of Fos immunoreactive cells in all lobes of the cerebellar vermis was similar between groups stimulated with almond extract and with oestrous odour, and higher than in the clean woodchip group. CONCLUSIONS: Stimulation of the main olfactory system (almond) and the accessory system (oestrous odour) increases Fos protein production in the granular layer of the cortex of the cerebellar vermis in naive male rats.

Inducción del temblor mandibular por lesión electrolítica del estriado ventrolateral y por el tratamiento subcrónico con haloperidol en rata macho: un contraste electromiográfico / Induction of mandibular tremor using electrolytic lesion of the ventrolateral striatum or using subchronic haloperidol therapy in male rats: An electromyographic comparison

Introducción: El temblor mandibular (TM) en la rata es inducido farmacológicamente por la manipulación dopaminérgica estriatal y por lesión del estriado ventrolateral (EVL). Este temblor tiene características neuroquímicas, anatómicas y electromiográficas similares al temblor que presentan los pacientes con parkinsonismo. Pero se desconocen las características electromiográficas de los temblores generados por la lesión electrolítica del EVL. Método: En ese estudio, se describió electromiográficamente el temblor mandibular generado por la lesión electrolítica bilateral del EVL y se comparó con el inducido por el tratamiento subcrónico (i.p.) con haloperidol, neuroléptico de selectividad alta como antagonista dopaminérgico del receptor D2. A ratas con lesión en la región ventrolateral del estriado, con un tratamiento subcrónico de haloperidol, y a un grupo control que solo recibió el vehículo, se les registró la actividad electromiografía del músculo temporal en condiciones basales y durante los TM. Resultados: La distribución de frecuencias del TM entre los grupos varió, puesto que las ratas con la lesión en el EVL mostraron TM de mayor amplitud y frecuencia EMG que las ratas tratadas con el haloperidol. La amplitud en condiciones basales difirió en los distintos grupos de ratas. Conclusiones: Se concluye que los TM asociados a la lesión electrolítica del EVL son de mayor amplitud y frecuencia que los generados por haloperidol, esto puede estar relacionado con el tipo de afectación estriatal

Introduction: Tremulous jaw movement (TJMs) in rats can be induced pharmacologically by striatal dopaminergic manipulation or electrolytic lesion of ventrolateral striatum (VLS). This tremor has neurochemical, anatomical and electromyographic (EMG) characteristics similar to those of tremor in Parkinson patients. However, the EMG characteristics of tremors generated by electrolytic lesion to the VLS have not yet been studied. Method: This study used electromyography to describe tremulous jaw movement generated by bilateral electrolytic lesion in the VLS and compare it to tremors induced using subchronic IP treatment with haloperidol, a dopaminergic D2 receptor antagonist. The experimental groups contained rats with a lesion in the ventrolateral striatum and rats on subchronic haloperidol treatment; the control group received only the vehicle. The EMG signal from the temporal muscle was recorded at baseline and during TJMs in all groups. Results: TMJ frequencies were heterogeneous among the groups. Rats with VLS lesion showed higher amplitude and frequency values than the haloperidol-treated rats. Amplitudes at baseline also differed among the groups. Conclusions: We conclude that TMJs associated with electrolytic lesion to the VLS show a higher frequency and amplitude than tremors induced by haloperidol. This may be related to the way striatum neurons are affected

Beyond the basal ganglia: cFOS expression in the cerebellum in response to acute and chronic dopaminergic alterations.

The suggestion of an anatomical and functional relationship between the basal ganglia and cerebellum is recent. Traditionally, these structures were considered as neuronal circuits working separately to organize and control goal-directed movements and cognitive functions. However, several studies in rodents and primates have described an anatomical interaction between cortico-basal and cortico-cerebellar networks. Most importantly, functional changes have been observed in one of these circuits when altering the other one. In this context, we aimed to accomplish an extensive description of cerebellar activation patterns using cFOS expression (cFOS-IR) after acute and chronic manipulation of dopaminergic activity. In the acute study, substantia nigra pars compacta (SNc) activity was stimulated or suppressed by intra cerebral administration of picrotoxin or lidocaine, respectively. In addition, we analyzed cerebellar activity after the induction of a parkinsonism model, the tremulous jaw movements. In this model, tremulous jaw movements were induced in male rats by IP chronic administration of the dopamine antagonist haloperidol (1.5mg/kg). Acute stimulation of SNc by picrotoxin increased cFOS-IR in the vermis and cerebellar hemispheres. However, lidocaine did not produce an effect. After 14days of haloperidol treatment, the vermis and cerebellar hemispheres showed an opposite regulation of cFOS expression. Chronic dopaminergic antagonism lessened cFOS expression in the vermis but up-regulated such expression in the cerebellar hemisphere. Overall, the present data indicate a very close functional relationship between the basal ganglia and the cerebellum and they may allow a better understanding of disorders in which there are dopamine alterations.

Induction of mandibular tremor using electrolytic lesion of the ventrolateral striatum or using subchronic haloperidol therapy in male rats: an electromyographic comparison.

INTRODUCTION: Tremulous jaw movement (TJMs) in rats can be induced pharmacologically by striatal dopaminergic manipulation or electrolytic lesion of ventrolateral striatum (VLS). This tremor has neurochemical, anatomical and electromyographic (EMG) characteristics similar to those of tremor in Parkinson patients. However, the EMG characteristics of tremors generated by electrolytic lesion to the VLS have not yet been studied. METHOD: This study used electromyography to describe tremulous jaw movement generated by bilateral electrolytic lesion in the VLS and compare it to tremors induced using subchronic IP treatment with haloperidol, a dopaminergic D2 receptor antagonist. The experimental groups contained rats with a lesion in the ventrolateral striatum and rats on subchronic haloperidol treatment; the control group received only the vehicle. The EMG signal from the temporal muscle was recorded at baseline and during TJMs in all groups. RESULTS: TMJ frequencies were heterogeneous among the groups. Rats with VLS lesion showed higher amplitude and frequency values than the haloperidol-treated rats. Amplitudes at baseline also differed among the groups. CONCLUSIONS: We conclude that TMJs associated with electrolytic lesion to the VLS show a higher frequency and amplitude than tremors induced by haloperidol. This may be related to the way striatum neurons are affected.