scholarly journals Calretinin Immunoreactivity in the VIIIth Nerve and Inner Ear Endorgans of Ranid Frogs

2021 ◽  
Vol 15 ◽  
Author(s):  
Ingrid Reichenberger ◽  
Claude J. Caussidier-Dechesne ◽  
Hans Straka

Calcium-binding proteins are essential for buffering intracellular calcium concentrations, which are critical for regulating cellular processes involved in neuronal computations. One such calcium-binding protein, calretinin, is present in many neurons of the central nervous system as well as those which innervate cranial sensory organs, although often with differential distributions in adjacent cellular elements. Here, we determined the presence and distribution of calretinin-immunoreactivity in the peripheral vestibular and auditory system of ranid frogs. Calretinin-immunoreactivity was observed in ganglion cells innervating the basilar and amphibian papilla, and in a subpopulation of ganglion cells innervating the saccular epithelium. In contrast, none of the ganglion cells innervating the lagena, the utricle, or the three semicircular canals were calretinin-immunopositive, suggesting that this calcium-binding protein is a marker for auditory but not vestibular afferent fibers in the frog. The absence of calretinin in vestibular ganglion cells corresponds with the lack of type I hair cells in anamniote vertebrates, many of which in amniotes are contacted by the neurites of large, calyx-forming calretinin-immunopositive ganglion cells. In the sensory epithelia of all endorgans, the majority of hair cells were strongly calretinin-immunopositive. Weakly calretinin-immunopositive hair cells were distributed in the intermediate region of the semicircular canal cristae, the central part of the saccular macula, the utricular, and lagenar striola and the medial part of the amphibian papilla. The differential presence of calretinin in the frog vestibular and auditory sensory periphery might reflect a biochemical feature related to firing patterns and frequency bandwidths of self-motion versus acoustic stimulus encoding, respectively.

1992 ◽  
Vol 186 (3) ◽  
pp. 1207-1211 ◽  
Author(s):  
Akio Nakano ◽  
Motomu Terasawa ◽  
Masato Watanabe ◽  
Nobuteru Usuda ◽  
Takashi Morita ◽  
...  

1987 ◽  
Vol 115 (1) ◽  
pp. 129-134
Author(s):  
E. M. W. Maunder ◽  
A. V. Pillay ◽  
A. D. Care

ABSTRACT An i.v. injection of calcitriol (1,25-(OH)2D3) had no effect within 2·5 h on plasma concentrations of calbindin-D9k (vitamin D-induced calcium-binding protein; CaBP) in hypocalcaemic pigs with inherited vitamin D-dependent rickets type I or in their normocalcaemic siblings or half-siblings. Three days later the plasma concentration of CaBP had doubled in the hypocalcaemic pigs, but was unaltered in the normocalcaemic siblings and half-siblings. Following daily i.v. injections of 1,25-(OH)2D3 for a further 5 days (days 4–8) plasma concentrations of CaBP increased in both the hypocalcaemic (days 4–8) and normocalcaemic (day 8) pigs, the effect being more rapid and greater in the hypocalcaemic 1,25-(OH)2D3-deficient animals. An i.v. injection of 1,25-(OH)2D3 to pure Yucatan pigs also had no effect on plasma concentrations of CaBP within 1·5 h, but in the following 1 h there was some indication of an increase in plasma CaBP levels. In contrast to the normal pigs, insulin-induced hypoglycaemia did not lead to a peak in plasma CaBP concentrations in the hypocalcaemic pigs. There was also no change in the plasma concentrations of 1,25-(OH)2D3 associated with the peak in plasma CaBP following insulin-induced hypoglycaemia in normocalcaemic pigs. These results suggest that changes in plasma concentrations of 1,25-(OH)2D3 are not directly involved in mediating the increase in plasma CaBP which follows hypoglycaemia induced by insulin in normal pigs, although 1,25-(OH)2D3 probably plays a permissive role. J. Endocr. (1987) 115, 129–134


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