Light microscopic analysis of golgi‐impregnated rat subthalamic neurons

Abstract

The neuronal morphology of the rat subthalamic nucleus (STH) was studied using Golgi techniques and Nissl stain. The results show that the somatic shapes of STH neurons vary from fusiform to oval or polygonal. Somatic cross-sectional areas vary between 140 microns2 and 440 microns2. Some of the cells have a few somatic spines. Two to six primary dendrites gave rise to tapering daughter dendrites which extend up to 500 microns. These dendrites are sparsely covered with spines. Some distal dendrites and primary dendrites of the STH also bear filiform appendages. Neurons located in the deep portion of the STH have oval dendritic fields whose long axis is parallel to the long axis of the nucleus in frontal or sagittal planes. Some of these neurons have one or two dendrites which cross the borders of the STH into the zona incerta, the lateral hypothalamus, or the cerebral peduncle. Generally, neurons located at the borders of the STH have their dendritic fields extending parallel to the borders and are confined to the nucleus. However, some neurons adjacent to the ventrolateral border of the nucleus have some dendrites extending into the cerebral peduncle. Quantitative analysis of the STH neurons showed a unimodal distribution of somatic sizes as well as the number of primary dendrites. No neurons with obvious Golgi type II characteristics were found. Two types of afferent fibers were observed entering the STH. One type consists of axon collaterals arising from the cerebral peduncle ventrolaterally, or the internal capsule rostrally, while the other enters the nucleus after crossing the internal capsule rostrally. These results suggest that the rat STH is an open nucleus in contrast to other species such as man, monkey, and cat, where it is closed, and that the rat STH may contain only one type of neuron.

Activation of Metabotropic Glutamate Receptor 5 Has Direct Excitatory Effects and Potentiates NMDA Receptor Currents in Neurons of the Subthalamic Nucleus

“…In sections immunostained for mGluR1a, labeled dendrites were found in the cerebral peduncle (Fig. 5A), which is consistent with previous Golgi studies showing that the dendrites of neurons located along the ventral border of the STN extend ventrally into the cerebral peduncle (Iwahori, 1978;Afsharpour, 1985).…”

Axonal collateralization in primate basal ganglia and related thalamic nuclei

“…The most abundant of these STN neurons were those projecting to the GPi and GPe, followed by STN neurons projecting to the SNr, GPi and GPe, those projecting toward the striatum, those targeting the GPe only, and finally STN neurons projecting to the SNr and GPe (Table 1). These findings are largely in agreement with earlier data derived from antidromic invasions, intracellular cell labeling, double-retrograde fluorescent and Golgi studies in rats (Deniau et al, 1978; Van Der Kooy and Hattori, 1980; Hammond and Yelnik, 1983;Afsharpour, 1985;Kita and Kitai, 1987;Granata and Kitai, 1989). These investigations have emphasized the highly branched nature of the axons of STN neurons, a finding that led to the concept that virtually all STN neurons have a similar somatodendritic morphology and an axon that branches to the pallidum and the substantia nigra.…”

Determinants of neuronal firing pattern in the guinea-pig subthalamic nucleus: Anin vivo andin vitro comparison

“…Sites close to (or within) the globus pallidus were effective, other sites producing only quantitatively different activity patterns. Since the bursts occurred after a short latency inhibition, and since the STN does not receive a direct input from the neostriatum (Afsharpour, 1985), evidence suggests that the globus pallidus was the source of the effective input at all stimulation sites producing a response. Stimulation of the dorsal pallidum can be inferred from the presence of antidromic spikes in the majority of cells, the lowest threshold electrode for which was usually closest to globus pallidus.…”