RESUMO
Large numbers of neurons were retrogradely labeled in both the dorsal and ventral medial terminal nucleus (MTN) after fluoro-gold injections into the rat pretectal nucleus of the optic tract/dorsal terminal nucleus (NOT/DTN). Fluorescence immunocytochemistry for GABA in the same brains revealed GABA-positive neurons distributed mainly in the dorsal MTN. Approximately half of all the GABAergic neurons in the MTN were double-labeled. Therefore, GABAergic neurons comprise a significant component of the MTN-NOT/DTN projection which most likely inhibits the pretectal pathway mediating horizontal optokinetic nystagmus.
Assuntos
Neurônios Eferentes/fisiologia , Estilbamidinas , Colículos Superiores/anatomia & histologia , Vias Visuais/anatomia & histologia , Ácido gama-Aminobutírico/fisiologia , Animais , Corantes Fluorescentes , Imuno-Histoquímica , Microscopia de Fluorescência , Ratos , Colículos Superiores/fisiologia , Vias Visuais/fisiologiaRESUMO
The projection to the olivary pretectal nucleus (OPN) from the contralateral eye is observed on the first day after birth and appears adult-like on postnatal day 5. The ipsilateral projection is present at postnatal day 4, and expands to fill the nucleus overlapping the contralateral projection, though never as dense, between days 6 and 8. Then, in normal hamsters, ipsilaterally projecting fibers retract to the ventral side of the OPN by day 10. However, the dense expanded projection in the dorsal OPN ipsilateral to the remaining eye in monocularly enucleated hamsters persists into adulthood.
Assuntos
Núcleo Olivar/crescimento & desenvolvimento , Retina/crescimento & desenvolvimento , Animais , Cricetinae , Enucleação Ocular , Peroxidase do Rábano Silvestre , Núcleo Olivar/anatomia & histologiaRESUMO
The projection to the olivary pretectal nucleus (OPN) from the contralateral eyes is observed on the first day after birth and appears adult-like on postnatal day 5. The ipsilaeral projection is present at postnatal day 4, and expands to fill the nucleous overlapping the contralateral projection, though never as dense, between days 6 and 8. Then, in normal hamsters, ipsilaterally projecting fibers retract to the ventral side of the OPN by day 10. However, the dense expanded projection in the dorsal OPN ipsilateral to the remaining eye in monocularly enucleated hamsters persists adulthood
Assuntos
Cricetinae , Animais , Núcleo Olivar/crescimento & desenvolvimento , Retina/crescimento & desenvolvimento , Enucleação Ocular , Peroxidase do Rábano Silvestre , Mesocricetus , Núcleo Olivar/anatomia & histologiaRESUMO
Large numbers of neurons were retrogradely labeled in both the dorsal and ventral medial terminal nucleous (MTN) after fluoro-gold injections into the rat pretectal nucleus of the optic tract/dorsal terminal nucleus (NOT/DTN). Fluorescence immunocytochemistry for GABA in the same brains revealed GABA-positive neurons distributed mainly in the dorsal MTN. Approximately half of all the GABAergic neurons in the MTN were double-labeled. Therefore, GABAergic neurons comprise a significant component of the MTN-NOT-DTN projection which most likely inhibits the pretectal pathway mediating horizontal optokinetic nystagmus
Assuntos
Ratos , Animais , Ácido gama-Aminobutírico/fisiologia , Neurônios Eferentes/fisiologia , Colículos Superiores/fisiologia , Vias Visuais/fisiologia , Corantes Fluorescentes/administração & dosagem , Imuno-Histoquímica , Microscopia de FluorescênciaRESUMO
The distribution of ganglion cell densities and sizes was studied in Nissl-stained flat-mount retinae of the two-toed sloth. The area centralis, a weak specialization with low ganglion cell density, is located in the temporal retina close to the center of the eye. The presence of a visual streak was noted. The distribution of different ganglion cell sizes was approximately equal throughout the retina. Although the retinal organization differs from that of the closely related three-toed sloth, the presumed function of retinal specializations in both species is to guide limb movements by permitting visualization of the branch along which the animal is climbing.
Assuntos
Gânglios Simpáticos/citologia , Retina/citologia , Bichos-Preguiça/anatomia & histologia , Xenarthra/anatomia & histologia , Adaptação Fisiológica , Animais , Retina/fisiologiaRESUMO
The distribution of ganglion cell densities and sizes was studied in Nissl-stained flat-mount retinae fo the two-toed sloth. The area centrailis, a weak specializtion with low ganglion cell density, is located in the temporal retina close to the center of the eye. The presence of a visual treak was nsoted. The distribution of different ganglion cell sizes was approximately equal throughout the retina. Although the retinal organization differs from that of the closely related three-toed sloth, presumed function of retinl specializations in both species is to guide limb movements by permiting visualization of the branch along which the animal is climbing
Assuntos
Animais , Gânglios Simpáticos/citologia , Retina/citologia , Bichos-Preguiça/anatomia & histologia , Xenarthra/anatomia & histologia , Adaptação Fisiológica , Retina/fisiologiaRESUMO
1. The distribution and size of retinal ganglion cells labelled with horseradish peroxidase (HRP) were studied in flat-mounted retinas of three-toed sloths. 2. Massive injections of HRP solution were made throughout the thalamus and midbrain in anesthetized sloths in order to retrogradely label the retinal ganglion cell population. Twenty to thirty h later the eyes were excised and the retinas flat-mounted and reacted with phenylenediamine-HCl and H2O2 to label ganglion cells, thus distinguishing them from other cells in the same retinal layer. 3. Ganglion cell density gradually increased from about 500 cells/mm2 at the far periphery to a peak of about 1,500 cells/mm2 in an area, termed the area centralis, deep in the inferior temporal retina. The presence of a vertical visual streak was also noted. 4. The area centralis contained a higher frequency of small ganglion cells than the peripheral retina where large cells predominated. 5. The unusual position of the area centralis and visual streak in the retina can be explained by the sloth's unique ability to rotate its head 180 degrees while climbing upside-down along horizontal branches so that the head is right-side-up. If it is assumed that the branch directly above the sloth's head needs to be visualized for accurate claw placement then the branch would be imaged on the inferior temporal retina in an area corresponding to the maximum density region.
Assuntos
Neurônios/citologia , Retina/citologia , Bichos-Preguiça , Xenarthra , Animais , Contagem de Células , Peroxidase do Rábano Silvestre/metabolismo , Neurônios/metabolismoRESUMO
Extraocular muscle motoneurones were localised in the oculomotor nucleus (ON), trochlear nucleus (TN) and abducens nucleus (AN) in the marmoset brain using the horseradish peroxidase (HRP) retrograde labelling technique. HRP pellets injected into individual extraocular muscles revealed one or more groups of labelled neurones occupying discrete loci within these nuclei. Relatively little overlap of motoneurone pools was observed, except in the case of the inferior oblique and superior rectus muscles. Injections of HRP into the medial rectus muscle revealed three separate populations of labelled cells in the ipsilateral ON. Motoneurones innervating the inferior rectus muscle were mainly localised in the lateral somatic cell column of the ipsilateral ON. A second smaller grouping was observed in the medial longitudinal fasciculus. The inferior oblique muscle motoneurones were localised in the ipsilateral medial somatic cell column intermingled with motoneurones supplying the superior rectus muscle of the opposite eye. The superior oblique muscle motoneurones occupied the entire TN and the lateral rectus muscle motoneurones the AN. It was concluded that the organisation of nuclei and subnuclei responsible for controlling the extraocular muscles in the marmoset is broadly similar to that of other primates.
Assuntos
Mapeamento Encefálico , Encéfalo/citologia , Callitrichinae/anatomia & histologia , Neurônios Motores/citologia , Músculos Oculomotores/inervação , Nervo Abducente/citologia , Animais , Peroxidase do Rábano Silvestre , Vias Neurais/anatomia & histologia , Nervo Oculomotor/citologia , Nervo Troclear/citologiaRESUMO
The slow potential change (spc) accompanying spreading depression (SD) was studied in rats and in a seizure-sensitive strain of Mongolian gerbil under three different experimental paradigms, each involving the use of naloxone. Gerbils undergoing electroconvulsive shock treatment displayed SD during the post-ictal phase, which was blocked by the intraperitoneal (i.p.) administration of naloxone (20-50 mg kg-1). Topical application of naloxone to the exposed cortex of the anaesthetized gerbil and rat blocked the spc of SD evoked by KCl. Microiontophoretic ejection of naloxone during extracellular recordings reversed cell refractoriness following the spc, demonstrated by the observation of a maintained sensitivity to iontophoretic pulses of glutamate. The results suggest a possible involvement of naloxone-sensitive processes in the mechanism responsible for cortical SD.
Assuntos
Córtex Cerebral/fisiopatologia , Depressão Alastrante da Atividade Elétrica Cortical/efeitos dos fármacos , Naloxona/farmacologia , Convulsões/fisiopatologia , Animais , Bicuculina/análogos & derivados , Bicuculina/farmacologia , Córtex Cerebral/efeitos dos fármacos , Eletroencefalografia , Eletrochoque , Gerbillinae , Glutamatos/farmacologia , Ácido Glutâmico , Injeções Intravenosas , Iontoforese , Naloxona/administração & dosagem , Ratos , Ratos Endogâmicos , Tempo de Reação/fisiologia , Ácido gama-Aminobutírico/farmacologiaRESUMO
1. The distribution ans size of retinal ganglion cells labelled with horseradish preoxidase (HRP) were studied in flat-mounted retinas of three-toed sloths. 2. Massive injections of HRP solution were made throughout the thalamus and midbrain in anesthetized sloths in order to retrogradely label the retinal ganglion cell population. Twenty to thirty h later the eyes were and the retinas flat-mounted and reacted with phenylenediamine-HCL and H2O2 to label ganglion cells,thus distinguishing then from other cells int he same retinal layer. 3. Ganglion cell density graually increased from about 500 cell/mm2 at the far periphery to a peak of about 1,500 cells/mm2 in an area, termed the area centralis, deep in the inferior temporal retina. The presence of a vertical visual steak was also noted. 4. The area centralis contained a higher frequency of small ganglion cells than the peripheral retina where large cells preominated. 5. /the unusual postion of the area centralis and cisual streak in the retina can be explained by the slot's unique ability to rotate its head 180- while climbing upside-dow along horizontal branches so that the head is right-side-up. If it is assumed that the branch directly above the sloth's head needs to be visualized for accurate claw placement then the branch would be imaged on the inferior temporal retina in an area corresponding to the maximum density region
Assuntos
Animais , Neurônios/citologia , Peroxidase do Rábano Silvestre/metabolismo , Xenarthra , Contagem de Células , Neurônios/metabolismo , Retina/citologia , Bichos-PreguiçaRESUMO
The motoneurons of the oculomotor complex responsible for controlling accommodation and pupil size of the marmoset were identified by injecting horseradish peroxidase (HRP) into the ciliary ganglion. The anatomical organization of accommodation and pupil constrictor motoneurons was determined using electrical stimulation techniques. HRP-labelled cells were found through the whole length of the Edinger-Westphal nucleus (EW) and also just ventral to this nucleus in caudal sections. A projection from the antero-median nucleus to the ciliary ganglion could not be demonstrated. Electrical stimulation data showed that currents of less than 1 microampere applied inside the EW evoked accommodation responses. Pupil constriction responses, on the other hand, were evoked with weak currents at sites ventral to those in the EW generating accommodation at caudal and central levels. It was concluded that the EW was responsible for accommodation and areas containing HRP-labelled cells ventral to the caudal part of the EW were responsible for pupil constriction.