title: Dopamine- and Tyrosine Hydroxylase-Immunoreactive Neurons in the Brain of the American Cockroach, Periplaneta americana.
abstract: The catecholamine dopamine plays several vital roles in the central nervous system of many species, but its neural mechanisms remain elusive. Detailed neuroanatomical characterization of dopamine neurons is a prerequisite for elucidating dopamine's actions in the brain. In the present study, we investigated the distribution of dopaminergic neurons in the brain of the American cockroach, Periplaneta americana, using two antisera: 1) an antiserum against dopamine, and 2) an antiserum against tyrosine hydroxylase (TH, an enzyme required for dopamine synthesis), and identified about 250 putatively dopaminergic neurons. The patterns of dopamine- and TH-immunoreactive neurons were strikingly similar, suggesting that both antisera recognize the same sets of "dopaminergic" neurons. The dopamine and TH antibodies intensively or moderately immunolabeled prominent brain neuropils, e.g. the mushroom body (memory center), antennal lobe (first-order olfactory center) and central complex (motor coordination center). All subdivisions of the mushroom body exhibit both dopamine and TH immunoreactivity. Comparison of immunolabeled neurons with those filled by dye injection revealed that a group of immunolabeled neurons with cell bodies near the calyx projects into a distal region of the vertical lobe, which is a plausible site for olfactory memory formation in insects. In the antennal lobe, ordinary glomeruli as well as macroglomeruli exhibit both dopamine and TH immunoreactivity. It is noteworthy that the dopamine antiserum labeled tiny granular structures inside the glomeruli whereas the TH antiserum labeled processes in the marginal regions of the glomeruli, suggesting a different origin. In the central complex, all subdivisions excluding part of the noduli and protocerebral bridge exhibit both dopamine and TH immunoreactivity. These anatomical findings will accelerate our understanding of dopaminergic systems, specifically in neural circuits underlying aversive memory formation and arousal, in insects.
authors: Faculty of Science, Hokkaido University, Sapporo, Hokkaido, Japan.
authors: Yoshitaka
authors: Y
authors: Hamanaka
authors: Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan.
authors: Run
authors: R
authors: Minoura
authors: Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, Japan.
authors: Hiroshi
authors: H
authors: Nishino
authors: Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan.
authors: Toru
authors: T
authors: Miura
authors: Faculty of Science, Hokkaido University, Sapporo, Hokkaido, Japan.
authors: Makoto
authors: M
authors: Mizunami
mesh_terms: D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives / Q000494:pharmacology; D001921:Brain / Q000033:anatomy & histology / Q000166:cytology* / Q000502:physiology; D004298:Dopamine / Q000276:immunology* / Q000378:metabolism; D005260:Female; D019476:Insect Proteins / Q000276:immunology / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism / Q000502:physiology; D010526:Periplaneta / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000276:immunology* / Q000378:metabolism
chemical_list: D019476:Insect Proteins; C070614:neurobiotin; D001710:Biotin; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine