ABSTRACT
Neurons expressing the calcium binding proteins (CaBPs) parvalbumin (PV) and calbindin (CB) have shown age-related density changes throughout the ascending auditory system of both rodents and macaque monkeys. In the cerebral cortex, neurons expressing these CaBPs express markers of γ-aminobutyric acidergic neurotransmission, such as GAD67, and have well-understood physiological response properties. Recent evidence suggests that, in the rodent auditory brainstem, CaBP-containing cells do not express GAD67. It is unknown whether PV- and CB-containing cells in subcortical auditory structures of macaques similarly do not express GAD67, and a better understanding of the neurotransmission of neurons expressing these proteins is necessary for understanding the age-related changes in their density throughout the macaque auditory system. This was investigated with immunofluorescent double-labeling techniques to coregister PV- and CB-expressing neurons with GAD67 in the superior olivary complex and the inferior colliculus of young and aged rhesus macaques. The proportions of GAD67-expressing PV- and CB-positive neurons were computed with unbiased sampling techniques. Our results indicate that between 42% and 62% of PV- and CB-positive neurons in the auditory brainstem and midbrain express GAD67, which is significantly less than in the cerebrum. In general, fewer PV(+) neurons and more CB(+) neurons expressed GAD67 as a function of age. These results demonstrate that the inhibitory molecular profile of PV- and CB-expressing neurons can change with age in subcortical auditory structures and that these neurons are distinct from the well-described inhibitory interneurons that express these proteins in the cerebral cortex.
Subject(s)
Aging/metabolism , Glutamate Decarboxylase/metabolism , Inferior Colliculi/metabolism , Macaca mulatta/metabolism , Neurons/metabolism , Superior Olivary Complex/metabolism , Aging/pathology , Animals , Calbindins/metabolism , Cell Count , Female , Fluorescent Antibody Technique , Inferior Colliculi/anatomy & histology , Macaca mulatta/anatomy & histology , Male , Microscopy, Fluorescence , Neurons/cytology , Parvalbumins/metabolismABSTRACT
At least one serologic marker of prior hepatitis B infection (hepatitis B surface antigen, antibody to surface antigen, or antibody to core antigen) was found in 91.7% of 314 Marshallese tested. The prevalence of hepatitis B surface antigenemia (3.3%) in a subpopulation that had resided on Rongelap Atoll at the time of accidental exposure to radioactive fallout from a thermonuclear test in 1954 did not differ significantly from the prevalence in a selected unexposed population (10.5%).