Synapsin I and Synaptophysin expression during ontogenesis of the mouse peripheral vestibular system

Abstract

Synapsin I and Synaptophysin are selectively localized in axonal endings of CNS neurons where they are associated with small synaptic vesicle membranes. The development of expression of these 2 proteins was studied by immunocytochemistry during ontogenesis of the peripheral vestibular system in the mouse. Both proteins are localized in vestibular ganglion neurons and in their peripheral sensory extensions as early as gestational day 14. While the entire periphery of these fibers is labeled during embryogenesis, both proteins are subject to relocation during the postnatal maturation of these fibers. In the mature vestibular receptors they disappear from the fibers themselves but are found concentrated in their intraepithelial endings and in the neuronal cell body. These observations show that the distribution pattern of Synapsin I and Synaptophysin in peripheral extensions of vestibular afferent neurons during development is identical to that described in axonal processes of CNS neurons. This suggests that the peripheral processes of the vestibular afferent neurons present structural and biochemical characteristics of axons. These characteristics are consistent with a bimodal sensory and secretory function of mature endings.

Differential Expression of Synaptophysin and Synaptoporin During Pre‐ and Postnatal Development of the Rat Hippocampal Network

“…Studies on the developmental expression of synaptophysin and synaptoporin in the central nervous system revealed that these proteins are present not only in mature terminals but also in outgrowing axons (Bergmann et al, 1991Scarfone et al, 1991;Ovtscharoff et al, 1993; this study) and, unexpectedly, in the cytoplasmic bridge connecting retinal photoreceptor cell bodies with the rod component (Schmied and Holtzman, 1989), in dendrites of the continuously regenerating olfactory receptor neurons and, transiently, in dendrites of developing hippocampal pyramidal neurons (this study). While synaptic vesicles in outgrowing axons could serve as a reservoir for subsequent synaptogenesis, synaptic vesicle membrane antigens in developing dendrites are unlikely to contribute to synaptic organelles.…”

Stem cells for the replacement of inner ear neurons and hair cells

“…The new neurons appeared to have some properties of presynaptic neurons during synaptogenesis: the expression of synaptic markers was localized to the neuronal side at the actual contact with the hair cell (Martinez-Monedero et al, 2006). The processes of spiral ganglion neurons that extend to hair cells during development stain for synapsin and synaptophysin (Scarfone et al, 1991) and it is possible that the identity of this peripheral process as a dendrite is only acquired after it forms a connection to the hair cell. Neurite outgrowth has been shown to occur before the identity of axons and dendrites is specified.…”

Synaptophysin Immunohistochemistry during Vestibular Hair Cell Recovery after Gentamicin Treatment

“…synaptophysin, and semiquantitative immunohistochemical techniques, to obtain an efficient panoramic view of the sensory organ innervation [Scarfone et al, 1988[Scarfone et al, , 1991. Synaptophysin is a 38000-dalton integral protein membrane present in vesicles thought to be involved in the release of neurotransmitter and trophic peptides in different regions of the central nervous system [Greengard et al, 1993;Jahn et al, 1985].…”

“…In the vestibular and auditory sensory epithelia, synaptophysin immunohistochemistry has been used as a marker for synaptogenesis during development of the inner ear [Sans and Scarfone, 1996;Scarfone et al, 1991;Sokolow-Lopez/Ayala/Honrubia ski and Cunningham, 1999]. In the vestibular organs of adult animals, immunoreactivity to this protein is found in the cytoplasm of hair cells, efferent vestibular nerve endings and also postsynaptically in the neck of the afferent calyces [Dechesne et al, 1997;Scarfone et al, 1988Scarfone et al, , 1991.…”

“…In the vestibular organs of adult animals, immunoreactivity to this protein is found in the cytoplasm of hair cells, efferent vestibular nerve endings and also postsynaptically in the neck of the afferent calyces [Dechesne et al, 1997;Scarfone et al, 1988Scarfone et al, , 1991. However, no reference has been made as to whether this protein is found in afferent boutons that have few or no synaptic vesicles.…”