A novel, fully automated rotometer for the study of turning behavior: comparison of results under different experimental conditions

Se describe un rotámetro totalmente automático destinado a la cuantificación del comportamiento rotatorio en ratas con lesión unilateral del sistema nigroestiado. Las partes fundamentales del rotámetro son: a) sensor compuesto a su vez por un disco perforado que reproduce la rotación del animal mediante giro homólogo y dos células infrarrojo, con emisor y receptor cada una de ellas; b) microprocesador que transforma los pulsos de las células fotoeléctricas en información computadorizada, memoriándola; c) impressora comercial conectada al microprocesador. La confiabilidad, utilidad y validez del rotámetro se ensayó en distintos grupos experimentales de ratas adultas. La destrucción unilateral de la zona compacta de la sustantia nigra con 6-hidroxidopamina o ácido Kaínico intracerebrales, produce rotación contralateral bajo administración de apomorfina (0.5 y 1 mg/Kg, s.c.). En cambio la apomorfina provoca rotación homólateral a la lesión en animales con destrucción electrolítica (1.5 mA, 15 s) de la nigra. Para obtener una actividad rotatoria significativa, la lesión electrolítica debe ubicarse en la región externa del núcleo (365+53.4 vueltas/60m en lesión externa (n=5); 97.3ñ19.5 en lesión interna (n=3); t=2.31, p<0,05. Apomorfina 0.5 mg/Kg, s.c.). En animales con lesión unilateral del caudado por ácido iboténico intracerebral, se observa rotación homolateral tanto a la apomorfina como a la bromocriptina tanto a la apomorfina como a la bromocriptina (10 y 30 mg/Kg, i.p.). Se comprueban dif

Effects of both 6-hydroxydopamine-induced and electrolytic lesion of the substantia nigra on the rotational behavior and audiogenic seizures in the rat

1. Twenty-eight male albino rats were evaluted for audiogenic seizure sensitivity by systematic observation and the recording of behavior by ethological methods. The animals were subjected to high-intensity acoustic stimulation and their behavior was evaluated by reference to an audiogenic severity index (SI). Animals were classified as susceptible (S) or resistant (R) depending on the SI value. R. animals were: 1) subjected to chemical lesion of the substantia nigra compacta with 6-hydroxydopamine (60HDA), followed by SI quantitation, contralateral electolytic lesion osf the substantia nigra reticulata and new SIevaluation (N = 10) received 0,9% saline followed by SI evaluation, contralateral sham (mechanical) lesion and new SI calculation; 3) another group (N = 10) was subjected to unilateral electrolytical lesion of the substantia nigra reticulata and SI evaluation. 2. Effects of asymmetry were observed after chemical or electrolytic lesions, but these alterations correlated only with increased audiogenic sensitivity in rats with electrolytic lesions in the substantia nigra reticulada. No bhevioral changes were observed in any of the cocntrols. The amplhetamine-induced rotational behavior presented a definite left pattern (ipsilateral to the 60HDA lesion) for the animals with bilateral lesions, with an asymmetry index of 98%, whereas the sham-lesioned controls showed a 60% asymmetry index which was not significant. 3. The relationship between asymmetry and ssimultaneous audiogenic sensitivity may correspond to changes in the basal ganglia possibly in the hypersensitive postsynaotic portions of the substantia nigra reticulata efferents

Efecto de la 6-Hidroxidopamina intracisternal sobre la respuesta cardiovascular producida por la oclusión carotidea y la asfixia en la rata / Effect of intracisternaly administered 6-Hidroxydopamine on cardiovascular responses produced by carotid occlusion and asphixia in the rat

La 6-Hidroxidopamina (6-OHDA), 200 *gx3 dosis, inyectada en la cisterna magna de la rata, produce a los 20-30 días postratamiento una abolición de la respuesta hipertensiva a la oclusión bilateral de las carótidas y un bloqueo casi total de la hipertensión producida por la asfixia. La sensibilidad de los vasos periféricos a la noradrenalina exógena no se modificó en los animales tratados con 6-OHDA, así como tampoco se modificó la respuesta vagal bradicardizante a la hipertensión producida por la noradrenalina. El tratamiento con 6-OHDA produjo un agotamiento del 75-100 por ciento de la noradrenalina del cerebro y la médula espinal La integridad de las terminaciones noradrenérgicas del sistema nervioso central parece indispensable en la producción de la descarga simpática central originada por estimulación de los barorreceptores y quimiorreceptores de la periferia

Lipasa de lipoproteínas en cerebro. II. Ausencia de respuesta a la administración de 6-hidroxidopamina en el ratón / Cerebral lipoprotein lipase. II. Absence of response to 6-hydroxydopamine administration in the mouse

Se investigó el efecto de la administración seriada de 6-hidroxidopamina (6-OHDA) sobre la actividad de lipasa de lipoproteinas (PLP) cerebral en el ratón. La inyección intraperitoneal de 4 dosis (una por semana) de 6-OHDA, 100 mg/Kg de peso, no produjo efecto sobre la actividad de LPL cerebral ni cambios en la depleción enzimática del cerebro por la administración de heparina (100 UL/Kg de peso, vía intraperitoneal). La 6-OHDA tampoco ejerció efecto sobre la actividad LPL cerebral in vitro. Hubo una retención significativa (p<0,05) de la actividad LPL en el corazón después de la administración de heparina en animales inyectados previamente con 6-OHDA. Se sugiere la existencia de diferencias estructurales importantes entre las LPL de cerebro y corazón

Induçäo de pseudogravidez em ratas pela administraçäo intraventricular de 6-hidroxidopamina / Induction of pseudopregnancy in rats by the intraventricular administration of 6-hydroxydopamine

Procurando verificar se a destruiçäo das vias catecolaminérgicas pela 6-hidroxidopamina modificava o ciclo estral de ratas, quando injetada no ventrículo lateral, observou-se o aparecimento de um quadro de pseudogravidez. Os resultados mostraram que esses animais apresentavam uma diminuiçäo da ingestäo de alimentos que se correlacionava com o período de pseudogravidez. Vários autores descrevem este efeito com a administraçäo de drogas antidopaminérgicas e discutem os resultados em termo de interaçäo ao nível de transmissores sinápticos. No presente trabalho, mostra-se que o efeito da 6-hidroxidopamina, que poderia ser discutido como uma inibiçäo do fator inibidor da prolactina, causando pseudogravidez, pode ser originado apenas pelo estresse da privaçäo de alimentos

Studies on rectal temperature of rats in relation to seasonal air temperature and morphine administration.

The present findings demonstrate that seasonal air temperature does not only influence the basal core temperature of rats, but also modifies the physiological/pharmacological actions of drugs. Thus, at low ambient temperature, intracerebroventricular on intraperitoneal administration of morphine produces mainly hypothermia followed by a secondary rise in rectal temperature. On the other hand, at high ambient temperature, the drug produces hyperthermia only. The hypothermic response at low ambient temperature is abolished by pretreatment of rats with 6-hydroxydopamine but not with phenoxybenzamine administration. This suggests that catecholamine pathway in the central nervous system is involved in morphine induced hypothermic response. Further, the role of cholinergic neurons in such response is also indicated.

Effect of foot-electroshock stress on cholinergic activity, tissue glycogen and blood sugar in albino rats.

The immediate or 24 hr delayed effects of 1-day (1-DS) or (7-DS) foot-electroshock stress in albino rats were studied on cardiac acetylcholine (ACh), blood and cardiac cholinesterase (ChE) activities, cardiac, hepatic and muscle glycogen contents and blood sugar concentrations. The effects of physostigmine (PHY), atropine, 6-hydroxydopamine (6-HD), vagotomy and adrenalectomy on 1-DS induced changes were also studied. 1-DS produced an increase in cardiac ACh content which lasted for 24 hr but repeated stress showed phenomenon of adaptation. There seems to be activation of autonomic cholinergic system in stress. 1-DS and 7-DS produced a short-lived inhibition of blood ChE activity and 7-DS also of cardiac ChE activity. Inhibition of ChE activity was probably related to release of adrenaline from adrenal medulla. 1-DS produced hepatic and muscle glycogenolysis with slight hypoglycaemia but without any effect on cardiac glycogen. Following repeated stress there was a phenomenon of adaptation. The hepatic and muscle glycogenolysis produced by stress is due to the release of adrenaline from adrenal medulla. Normally functioning cardiac cholinergic system seems to have a protective effect on heart against stress, in the absence of which cardiac glycogenolysis is induced by stress.

Further studies on the mechanism of rise in blood pressure and tachycardia after intraventricular administration of aconitine.

Intraventricular administration of aconitine nitrate (10 mug) consistently produced hypertension and tachycardia. Peripheral vaso-constriction due to increase in central vasomomotor tone mainly responsible for hypertension whereas stimulation of central beta-receptors with sympathoadr renal discharge responsible for tachycardia.