1994 Fiscal Year Final Research Report Summary
Mode of steroid action involving in the behavioral regulation
| Project/Area Number |
05640749
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
生物形態・構造
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
TSUTSUI Kazuyoshi Faculty of Integrated Arts and Sciences, Hiroshima University Associate Professor, 総合科学部, 助教授 (20163842)
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| Project Period (FY) |
1993 – 1994
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| Keywords | bird / instinct behavior / memory ; learning / brain / neuron / steroid hormone / neurosteroid / neuropeptide |
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| Research Abstract |
Avian reproductive behaviors are under androgen regulation.To identify the neuropetides that are implicated in the regulation of steroid hormone dependent behavioral processes in birds.We have isolated three opioid peptides, i.e.Met-and Leu-enkephalins and Met-enkephalin-Arg-Phe.This is the first direct demonstration of the presence of opioid peptides in the avian brain.All of the three opioid peptides inhibited the spontaneous firing activities of subsets of neurons in the preoptic and hypothalamic areas that are known to be involved in the regulation of several reproductive behavior.Such an effect was completely blocked by naloxone, an opioid receptor antagonist.It may be possible that opioid peptides regulate some reproductive behavior through the mechanism that provokes the inhibition of neuronal activities.
It is well known that the brain is a target site of steroid hormones supplied by peripheral steroidogenic glands.However, present biochemical experiments demonstrated that the avian brain produces pregnenolone from cholesterol.Most accumulation of pregnenolone in the brain may be independent of the peripheral endocrine gland system.To understand the localization of cells involving with pregnenolone synthesis, the immunohistochemical study with the antibody against cytochrome P450_<scc> was further undertaken in the avian brain.
Clusters of immunoreactive cell bodies were detected in several telencephalic, diencephalic and mesencephalic regions.An intense immunoreaction was detected in somata of Purkinje cells and in the dendrites extending through the cerebellar molecular layr.Western immunoblot analysis with the P450scc antibody confirmed the presence of a P450scc-like substance in these brain regions.Immunohistochemistry using a specific marker protein of glial cells revealed that both neuronal and glial cells possess a P450scc-like substance in the avian brain.
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