title: Age-related changes in the expression of NMDA, serotonin, and GAD in the central auditory system of the rat.
abstract: CONCLUSIONS
  We suggest that age-induced changes of serotonin, N-methyl-d-aspartate receptor (NMDAR), and glutamate decarboxylase (GAD) expression in rats are dependent on the specific location in the central auditory system (CAS).
  
  
  OBJECTIVE
  Despite the importance of understanding changes in neurotransmitters during presbycusis, only a few studies have assessed age-associated changes in neurotransmitter at each level of the CAS. We therefore evaluated effects of aging on neurotransmission in the CAS of rats.
  
  
  METHODS
  The concentrations of serotonin, NMDAR, and GAD were assayed immunohistochemically in the cochlear nucleus (CN), superior olivary nucleus (SON), inferior colliculus (IC), medial geniculate body (MGB), and auditory cortex (AC) of Sprague-Dawley rats, aged 2 weeks (n = 20) or 24 months (n = 20).
  
  
  RESULTS
  The total number of neuronal cell bodies of the CAS did not differ significantly at each level between young and aged rats (p > 0.05). Serotonin expression was increased with age in the IC and MGB, but decreased in the CN, SON, and AC (p < 0.05). NMDAR was significantly higher in the CN, MGB, and AC of aged compared with young rats, but was significantly decreased over time in the SOC and IC (p < 0.05). GAD67 was increased with age in the MGB and AC and decreased in the CN and SON (p < 0.05), but was not changed in the IC.
authors: Department of Otorhinolaryngology, Eulji Hospital, Eulji University School of Medicine, Seoul, Korea.
authors: Hyun Joon
authors: HJ
authors: Shim
authors: Lae Hyung
authors: LH
authors: Lee
authors: Youngbuhm
authors: Y
authors: Huh
authors: So Yoon
authors: SY
authors: Lee
authors: Seung Geun
authors: SG
authors: Yeo
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D001303:Auditory Cortex / Q000378:metabolism*; D017626:Cochlear Nucleus / Q000378:metabolism*; D005829:Geniculate Bodies / Q000378:metabolism*; D005968:Glutamate Decarboxylase / Q000096:biosynthesis*; D007150:Immunohistochemistry; D007245:Inferior Colliculi / Q000378:metabolism*; D008297:Male; D016202:N-Methylaspartate / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000096:biosynthesis*; D009435:Synaptic Transmission
chemical_list: D012701:Serotonin; D016202:N-Methylaspartate; D005968:Glutamate Decarboxylase