Effects of injection of serotonin into nucleus caudatus on food and water intake and body weight in albino rats.

Serotonin is known to inhibit food and water intake. However, the effect of its injection into nucleus caudatus on food and water intake is not known. In the present study, serotonin hydrochloride, buspirone (the serotonin 5-HT1A agonist) and ondensetron (the 5HT3 antagonist) were injected into nucleus caudatus through stereotaxically implanted cannulae in three different dosages (1, 2 and 5 microg) and their effects on 24 h food and water intake, and body weight were recorded. The injection of serotonin hydrochloride resulted in a dose- dependent decrease in food intake attaining maximum of 27.3% at 5 microg dose, whereas water intake and body weight were decreased 12% and 4.3% respectively only at the highest does. Buspirone elicited a dose dependent inhibition of food and water intake and body weight (22.3%, 19.8% and 5.1% respectively), whereas ondensetron elicited an increase in food and water intake (37.8% and 36.3% respectively) without significantly altering bodyweight. It was concluded that serotonin hydrochloride injected into nucleus caudatus inhibits food and water intake significantly. These effects are mediated via 5-HT1A and 5HT3 receptors. The effect of injections of 5-HT1A receptor agonist is more pronounced on water intake. The effect of injections of 5HT3 receptor antagonist is also more pronounced on water intake.

Modulation of feeding and drinking behaviour by catecholamines injected into nucleus caudatus in rats.

Lesions of nucleus caudatus have been documented to produce adipsia and aphasia in rats. Injection of dopamine into this nucleus has been shown to facilitate water intake in rats. But, reports are not available on the effects of intracerebral injection of epinephrine and norepinephrine on feeding and drinking behaviour in animal models. Therefore, in the present study the effect of adrenaline and noradrenaline injected into nucleus caudatus on food and water intake in rats was assessed. 24 h basal food and water intakes were recorded in Wistar rats and were found to be 12.37 +/- 0.20 g and 22.04 +/- 0.27 ml respectively. Stainless steel cannulae were implanted stereotaxically into the nucleus caudatus. Four different doses (0.1 microgram, 0.5 microgram, 1 microgram, and 2 micrograms) of adrenaline and noradrenaline were injected into the nucleus caudatus through the implanted cannulae in separate groups of animals and their 24 h food and water intakes were recorded following these injections. No change in food and water intake was observed following the administration of different doses of adrenaline. A significant increase in 24 h food intake reaching a maximum of 16.03 +/- 0.15 g at 2 micrograms dose, without change in water intake was observed following administration of different doses of noradrenaline. The noradrenaline-facilitated food intake was blocked when noradrenaline was injected following injection of phentolamine, an alpha-receptor blocker. The bilateral lesions of nucleus caudatus resulted in a significant and sustained inhibition of food (8.98 +/- 0.17 g) and water intake (19.12 +/- 0.16 ml). These observations suggest that nucleus caudatus is involved in regulation of food and water intakes in rats. Noradrenaline-facilitated food intake is mediated by alpha-receptors. Adrenaline does not affect these ingestive behaviours when injected into the nucleus caudatus in rats.

Efectos de la 17 alfa-hidroxi-progesterona sobre la transmission cortico-caudado en ratas / Effects of 17 alpha-hydroxy-progesterone on cortico-caudate transmission in rats

Los efectos estrógenos y la progesterona en el control endocrino de las funciones sexuales son bien conocidos. Sin embargo, su papel en el control de áreas extrahipotalámicas ha sido poco estudiado. Trabajos previos realizados en nuestro laboratorio demuestran que el 17 Beta-Estradiol tiene un efecto inhibitorio en la transmisión cortico-caudado. En el presente trabajo se exploraron los efectos de la inyección intravenosa de 17 alpha-Hidroxi-Progesterona sobre esta misma conexión. Ratas hembras intactas, hembras ovariectomizadas y machos intactos, de la variedad Sprague Dawley, de 250 a 300 g de peso, fueron anestesiadas con Hidrato de Cloral (40 mg/100 g; i.p.). La hormona se administró a través de um catéter colocado en la vena yugular derecha (10 mul; 2,5 mg/ml). Se usaron métodos electrofisiológicos convencionales, utilizando electrodos de vidrio para el registro de las respuestas en el Caudado y electrodos metálicos para la estimulacióncortical, aislados excepto en la punta. Las respuestas excitatorias fueron analizadas por una computadora, integrando barridos sucessivos para construir histogramas post-estímulos. La administración de la 17 alpha-Hidroxi-Progesterona produjo un aumento significativo de las respustas en la mayoría de las células (95 por ciento). En algunas células (35 por ciento), este aumento fue acompañado de una disminución también significativa. En una sola neurona la respuesta excitatoria disminuyó. Los cambios descritos se observaron a partir de los primeros 5-10 minutos después de la administración hormonal, y se prolongan por una hora o más, luego de lo cual se observa recuperación de la respuesta inicial. Los resultados demuestran que la 17 alpha-Hidroxi-Progesterona estimula la transmisión cortico-caudado en la rata. La corta latencia de estos efectos hace suponer que pueden estar mediados por mecanismos no genómicos.

Modulation of feeding and drinking by dopamine in caudate and accumbens nuclei in rats.

Injection of dopamine (DA) into accumbens and caudate nuclei facilitates a dose-dependent increase in food and water intake, whereas administration of spiperone (SP), a central D2-receptor antagonist suppresses DA-facilitated food and water intake. Bilateral lesions of nucleus accumbens and caudatus result in a sustained and significant decrease in food and water intake. The results suggest that DA is a neurotransmitter involved in feeding and drinking behavior in accumbens and caudate nuclei and this effect is mediated by central D2 receptors.