Masanori Kitajiri

Localization of calcitonin gene-related peptide in the organ of Corti of the rat: an immunohistochemical study

The localization of calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRPI) structures in the cochlea was examined in the rat using immunocytochemistry. Numerous CGRPI fibers entered the organ of Corti in the intraganglionic spiral bundle and formed a dense fiber patch at the base of the inner hair cells. Much fewer, but still a significant number of CGRPI fibers were seen at the synaptic region of the outer hair cells. Since no immunoreactive cells were seen in the organ of Corti and spinal ganglion, these fibers may be one of the major components of the olivocochlear bundles originated from the superior olivary complex.

The presence of a calcitonin gene-related peptide in the olivocochlear bundle in rat

SummaryThe origins of calcitonin gene-related peptide immunoreactive (CGRPI) fibers in the cochlea were examined in rats. Parasagittal transection of the brain just medial to the principal sensory trigeminal nucleus resulted in the ipsilateral disappearance of CGRPI fibers in the cochlea, indicating that the origins of these fibers lie in the central nervous system. Next, we used a highly sensitive method combining retrograde tracing and immunohistochemistry to identify the origins of the CGRPI fibers in the cochlea. After injection of biotin-wheat germ agglutinin (b-WGA) into the cochlea, CGRPI neurons in the ipsilateral lateral superior olivary nucleus also contained b-WGA granules. These findings indicated tht CGRPI efferent fibers are major components of the olivocochlear bundle.

Effects of Topical Capsaicin on Autonomic Nerves in Experimentally-induced Nasal Hypersensitivity: An immunocytochemical study

Effects of capsaicin on autonomic nerves in the nasal mucosa and olfactory bulb of toluene diisocyanate sensitized guinea pigs were studied using immunocytochemistry. In the nasal mucosa, substance P (SP)- and tyrosine hydroxylase (TH)-like immunoreactive (SPI and THI) fibers seemed to decrease after capsaicin application. Calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRPI) fibers did not show obvious alterations. In the olfactory bulb, SPI and CGRPI fibers were few and the effects of capsaicin on those fibers were difficult to evaluate. THI fibers seemed not to be affected by capsaicin. It is suggested that capsaicin affects not only sensory nerves but that it also impacts on THI sympathetic nerves in the nasal mucosa.

Ontogeny of calcitonin gene-related peptide in the organ of Cortl of the rat ☆

The ontogeny of calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRPI) fibers in the rat cochlea was examined using immunocytochemistry. It was found that the CGRPI cochlear system developed markedly in the postnatal period; CGRPI fibers first appeared in the inner spiral bundle at postnatal day 8, then at the base of the outer hair cells, tunnel spiral bundle and tunnel radial fibers at postnatal day 19. The ontogenetical profile elucidated by this study suggests that CGRP has a role as a neuromodulator or neurotransmitter in this system.

Coexistence of calcitonin gene-related peptide and enkephalin in single neurons of the lateral superior olivary nucleus of the guinea pig that project to the cochlea as lateral olivocochlear system

Abstract Immunocytochemical double staining analysis revealed that some of the calcitonin gene-related peptide-containing neurons in the lateral olivary nucleus contained enkephalin in the guinea pig.

Immunolocalization of tyrosine hydroxylase and vasoactive intestinal polypeptide in nerve fibers innervating human palatine tonsil and paratonsillar glands.

The presence of tyrosine hydroxylase (TH) and vasoactive intestinal polypeptide (VIP) in the nerve fibers of the human palatine tonsil and paratonsillar secretory glands is reported. By immunohistochemistry TH-immunoreactive nerves and those immunoreactive to VIP were localized to the tonsil, in particular, the tonsillar vessel wall, extranodular lymphoid tissue and lymph nodule, and to the acinar basal surface of the paratonsillar glands. In the lymph nodule, immunoreactive varicose nerve profiles were observed inside the marginal zone. The germinal center was devoid of immunoreactive fibers.

Electron microscopic observation of calcitonin gene-related peptide-like immunoreactivity in the organ of Corti of the rat

Calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRP-IR) nerve terminals in the organ of Corti of rats were studied by light and electron microscopy. Surface preparation of the organ of Corti were immunostained using anti-CGRP antiserum for avidin-biotin immunohistochemistry. Dense CGRP-IR fiber bundles were observed by light microscopy in the inner spiral bundles, tunnel spiral bundles and outer spiral bundles. Electron microscopic analysis indicated that CGRP-IR fibers belong to efferent nerves. In the inner spiral bundles, the CGRP-IR fibers showed a direct contact mainly with non-immunoreactive afferent fibers. Some CGRP-IR nerve endings in the inner spiral bundles formed contacts directly with inner hair cells. In the outer spiral bundles, CGRP-IR fibers formed synaptic contacts exclusively with the outer hair cells. It should be noted that the number of synapses of CGRP nerve endings with outer hair cells varied depending upon the sub-row: a falling gradient in number occurred along the inner-outer axis. Our results suggest that CGRP acts as an efferent neuromodulator in the organ of Corti.

Hearing results for ossicular reconstruction using a cartilage-connecting hydroxyapatite prosthesis with a spearhead.

Objective: Assessment of the efficacy of ossicular reconstruction using a cartilage-connecting hydroxyapatite prosthesis designed with a spearhead to reduce extrusion and dislocation of the implant. Patients: All patients undergoing ossicular reconstruction after chronic ear surgery, connecting the cartilage to the prosthesis, with a minimum of 1 year of postoperative follow-up. Main Outcome Measures: Postoperative change in pure-tone averages. Air-bone gap closures, and implant extrusion rates. Results: Overall mean pure-tone averages improved by 12.2 dB (ranged between −40 and 60 dB). In total, 68.4% of the patients achieved an air-bone gap less than 20 dB. Gains in the mean air conduction thresholds were 9.5 dB in cases of partial ossicular reconstruction and 14.9 dB in cases with total ossicular reconstruction (p < 0.05). The overall extrusion rate was 4.21%. Conclusion: The cartilage-connecting hydroxyapatite prosthesis with a spearhead was found to restore hearing to a satisfactory level. The extrusion rate was relatively low. The cartilage-connecting hydroxyapatite prosthesis with a spearhead is an effective ossicular implant and offers an attractive alternative for ossicular reconstruction, particularly for total ossicular reconstructions.

Auditory pathway and auditory brainstem response in mice lacking NMDA receptor ϵ1 and ϵ4 subunits

Abstract There is considerable evidence that the N -methyl- d -aspartate receptor ((NMDAR) is a component of excitatory amino acid synapses in the ascending auditory pathway. The availability of mice that are defective in NMDAR ϵ 1 or NMDAR ϵ 4 subunit paves the way for investigations on the role of this receptor in auditory function. Non-radioactive in situ hybridization was used in the parent C57/6J wild strain to determine if these subunits are normally expressed in cochlear nucleus (CN) and superior olivary complex (SOC) and to confirm their absence in the respective mutant mice. Evoked auditory brainstem response (ABR) to normal acoustic stimulation was investigated to assess function. In situ hybridization revealed the expression of NMDAR ϵ 1 and ϵ 4 subunits mRNAs in major neuronal types in the CN and SOC of the wild type mice while ϵ 1 and ϵ 4 expression were absent in their respective mutant mice. The ABR threshold for the ϵ 1 mutant mice was similar to that of wild type mice however the threshold for the ϵ 4 mutant mice was significantly elevated. These results suggest a role for the NMDAR ϵ 4 in normal auditory functions while the NMDAR ϵ 1 may have a less critical function under normal conditions.

Autoradiographic localization of somatostatin mRNA in the adult rat lower brainstem: observation by the double illumination technique.

Using in situ hybridization histochemistry and observation with a double (dark and bright) illumination apparatus, the precise localization of preprosomatostatin mRNA was studied in the adult rat lower brainstem and cerebellum. It has previously been hard to localize the somatostatin precursor gene in the adult rat brainstem, because the level of expression is low or undetectable in some brain areas in adulthood, in contrast to the high levels in the neonatal period. The present study in adult rats showed the clear localization of this mRNA in the same areas where it is found in the perinatal period. The results showed that somatostatin neurons in such areas continue the minimal production of the precursor gene even at the adult stage.