Neurochemistry of olivocochlear neurons in the hamster.
The present study was conducted to characterize the superior olivary complex (SOC) of the lower brain stem in the pigmented Djungarian hamster Phodopus sungorus. Using Nissl-stained serial cryostat sections from fresh-frozen brains, we determined the borders of the SOC nuclei. We also identified olivocochlear (OC) neurons by retrograde neuronal tracing upon injection of Fluoro-Gold into the scala tympani. To evaluate the SOC as a putative source of neuronal nitric oxide synthase (nNOS), arginine-vasopressin (AVP), oxytocin (OT), vasoactive intestinal polypeptide (VIP), or pituitary adenylate cyclase-activating polypeptide (PACAP) that were all found in the cochlea, we conducted immunohistochemistry on sections exhibiting retrogradely labeled neurons. We did not observe AVP-, OT-, or VIP-immunoreactivity, neither in OC neurons nor in the SOC at all, revealing that cochlear AVP, OT, and VIP are of nonolivary origin. However, we found nNOS, the enzyme responsible for nitric oxide synthesis in neurons, and PACAP in neuronal perikarya of the SOC. Retrogradely labeled neurons of the lateral olivocochlear (LOC) system in the lateral superior olive did not contain PACAP and were only infrequently nNOS-immunoreactive. In contrast, some shell neurons and some of the medial OC (MOC) system exhibited immunofluorescence for either substance. Our data obtained from the dwarf hamster Phodopus sungorus confirm previous observations that a part of the LOC system is nitrergic. They further demonstrate that the medial olivocochlear system is partly nitrergic and use PACAP as neurotransmitter or modulator.
Reuss
Stefan
S
Department of Anatomy and Cell Biology, School of Medicine, Johannes Gutenberg-University, Mainz, Germany. reuss@uni-mainz.de
Disque-Kaiser
Ursula
U
Antoniou-Lipfert
Patricia
P
Gholi
Maryam Najaf
MN
Riemann
Elke
E
Riemann
Randolf
R
D000818:Animals; D001127:Arginine Vasopressin / Q000032:analysis / Q000378:metabolism; D001306:Auditory Pathways / Q000166:cytology / Q000378:metabolism*; D003051:Cochlea / Q000166:cytology / Q000378:metabolism*; D006224:Cricetinae; D004525:Efferent Pathways / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D026602:Nitrergic Neurons / Q000166:cytology / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000032:analysis / Q000378:metabolism; D009847:Olivary Nucleus / Q000166:cytology / Q000378:metabolism*; D010121:Oxytocin / Q000032:analysis / Q000378:metabolism; D017111:Phodopus / Q000033:anatomy & histology / Q000378:metabolism*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000032:analysis / Q000378:metabolism; D011149:Pons / Q000166:cytology / Q000378:metabolism*; D013194:Staining and Labeling; D013266:Stilbamidines
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D013266:Stilbamidines; D001127:Arginine Vasopressin; D009569:Nitric Oxide; D010121:Oxytocin; D052248:Nitric Oxide Synthase Type I