Biomaterial Database

Loss of axosomatic synapses in the dentate gyrus of aged rats. 1979

Y Geinisman

Axosomatic synapses involving granule cells of the dentate gyrus were studied by means of quantitative electron microscopic analysis in young adult (3-month-old) and aged (25-month-old) rats. The number of axosomatic synapses per unit length of neuronal soma membrane was found to be significantly lower (by 15%) in aged animals than in young adults. This decrease in synaptic numbers is not associated with age-related changes in the size of neuronal soma profiles or in the length of their plasma membranes. The ratio between the total length of synaptic appositions and the membrane length of a neuronal soma profile was diminished by 22% in aged rats, whereas the mean length of synaptic apposition was 10% less in these animals than in young adults. These data, taken together, suggest that an absolute loss of axosomatic synapses occurs with advanced age. It appears, therefore, than not only the loss of axodendritic synapses, described previously, but also the loss of axosomatic synapses, found here, contributes to the process of age-related partial deafferentation of neurons in the rat dentate gyrus.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D003712	Dendrites	Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.	Dendrite
D006624	Hippocampus	A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation.	Ammon Horn,Cornu Ammonis,Hippocampal Formation,Subiculum,Ammon's Horn,Hippocampus Proper,Ammons Horn,Formation, Hippocampal,Formations, Hippocampal,Hippocampal Formations,Hippocampus Propers,Horn, Ammon,Horn, Ammon's,Proper, Hippocampus,Propers, Hippocampus,Subiculums
D000344	Afferent Pathways	Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.	Afferent Pathway,Pathway, Afferent,Pathways, Afferent
D000375	Aging	The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.	Senescence,Aging, Biological,Biological Aging
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001369	Axons	Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.	Axon
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus