Synaptic organization of the human striatum: A postmortem ultrastructural study

Abstract

The goal of this study was to characterize the synaptic organization of the normal human adult striatum for comparison with other species and with the diseased human striatum. Samples of striatal tissue from the Maryland Brain Collection obtained at autopsy with postmortem intervals of less than 4 hours were prepared for electron microscopic analysis according to standard techniques. The caudate nucleus and the putamen were similar in terms of the proportions of synaptic subtypes, the lengths of synaptic subtypes, and the area of most types of axon terminals. The proportions of major striatal synaptic subdivisions, such as axospinous synapses (83.5%) and asymmetric synapses (77.5%), were similar to that of the monkey (82% and 77%, respectively) but slightly lower than found in the rat (90% and 89%, respectively). Interestingly, the proportion of synapses with perforated postsynaptic densities (23%), a type of synapse thought to represent synaptic plasticity, was much higher in humans than in rats (5-8%). The lengths of asymmetric synapses (0.697 micron) were significantly longer than that of symmetric synapses (0.423 microns), a relationship found in other mammals. Also, the areas of terminals forming asymmetric synapses (0.707 micron2) were larger than those forming symmetric synapses (0.401 micron2), also consistent with data from other species. The length of axospinous synapses (0.656 micron) and the area of the terminals forming them (0.611 micron2) were not significantly different from the length of axodendritic synapses (0.523 micron) or the area of terminals forming them (0.602 micron2). This study is the first quantitative study on synaptic organization in human postmortem striatum. The results indicate that the synaptic organization of the human striatum is similar, but not identical, to that of other mammalian species.

Cholinergic interneurons in the dorsal and ventral striatum: anatomical and functional considerations in normal and diseased conditions

“…Qualitative electron microscopic observations of either Golgi‐impregnated spidery neurons or ChAT‐immunoreactive cells in the primate dorsal striatum have revealed that ChIs receive symmetric and asymmetric synaptic inputs from morphologically heterogeneous terminal boutons indicative of diverse sources (Fig. ) . In a recent quantitative study, we demonstrated that 60% of all terminals in contact with ChIs in the monkey postcommissural putamen are GABAergic, while about 20% are putatively glutamatergic (asymmetric synapses/GABA‐negative), and the remaining 20% are of unknown chemical phenotype (symmetric synapses/GABA‐negative) (Fig.…”

Acid‐induced denaturation of Escherichia coli ribonuclease HI analyzed by CD and NMR spectroscopies

“…To our knowledge, this is the first quantitative electron microscopic analysis using stereologic techniques comparing the synaptic organization of the patch matrix compartment of the striatum, in any species. There are differences in striatal anatomy among different species even among mammals, including differences in synaptic organization (Dube et al, 1988; Sadikot et al, 1992b; Smith et al, 1994; Roberts et al, 1996). Although the results of the present study may apply to the ultrastructure of other species, particularly non‐human primates, definitive experiments would be needed to demonstrate similarities or differences.…”

“…In various mammalian species (Pasik et al, 1976; Chung et al, 1977; Hassler et al, 1978; Roberts et al, 1995a, b) including human (Roberts et al, 1996), the majority of synapses present in the striatum form asymmetric synapses, characteristic of excitatory synaptic transmission. The terminals forming these synapses originate predominantly from neurons in the cortex (Kemp and Powell, 1971a, b, c), with less extensive inputs arising from the thalamus (Kemp and Powell, 1971a, b, c; Sadikot et al, 1992a, b; Smith et al, 1994) and the raphe (LaVoie and Parent, 1990).…”

An examination of synaptic proteins following chronic haloperidol in a rat model of tardive dyskinesia.

“…Other studies have compared High and Low VCM rats as far as neuronal spine size and density. In the mammalian striatum the most prevalent neuronal subtype is the medium spiny projection neuron and the majority of striatal synapses are formed with these spines (Chung, Hassler, & Wagner, 1977;Hassler, Chung, Rinne, & Wagner, 1978;Kemp & Powell, 1971a, 1971bRoberts, Gaither, Peretti, Lapidus, & Chute, 1996). Thus, changes in spine size or density could have profound effects on striatal synaptic organization.…”