1987 Fiscal Year Final Research Report Summary
Participation of the Brain Opioid Systems in Affective Disorders
| Project/Area Number |
61570519
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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 |
Psychiatric science
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| Research Institution | Tokyo Medical and Dental University Grant-in-Aid for Scientific Research C |
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Principal Investigator |
SHIBUYA Haruo Tokyo Medical and Dental University, 医学部, 講師 (10158959)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Ryo Tokyo Medical and Dental University, 医学部, 教授 (70009918)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Imipramine / Clomipramine / Mianserin / Depression / Methionine-Enkephaline-Immunoreactivity / <mu>-Opioid Receptor / <delta>-Opioid Receptor / うつ病 |
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| Research Abstract |
In our experiments, the typical and atypical antidepressants were administered acutely or chronically into rats and hot plate analgesia, methionine-enkephalin-immunoreactivity (ME-I), <mu>-opioid receptor and <delta>-opioid receptor in various brain areas were investigated.
1. Acute effects of antidepressants
The single injection of imipramine (IMI) made no significant changes of ME-I in the frontal cortex, the limbic brain area, the striatum and the hypothalamus, except the hippocampus.
2. Chronic adminsistration of antidepressants.
Food pellets containig IMI, clomipramine (CLO) or mianserin (MIA) were edministered for 40 days to the rat.
(1) Analgesic effects of antidepressants were determined by the hot plate method. After 11 days treatment, the pain threshold significantly incereased, however, on the 39th day of treatment, no tolerance to nociceptive was detected.
(2) Methionine-enkephalin immunoreactivity
Although these drugs did not change the ME-I in the frontal cortex, ME-I significantly decreased in the limbic brain area and the striatum. And that in the hippocampus reversely increased with CLO or MIA.
(3) Opioid receptor bindings
Chronic treatment with IMI, CLO, MIA commonly resulted in decreases of <mu>-type and <deta>-type opioid receptor binding, as well as decrease of ME-I in the limbic brain area and the striatum in part. These finding shows the hypoactivity of opioid system in these brain areas following chronic antidepressants treatment. The hypothesis that the byperactivity of the opioid systems in these brain regions in depression might be supported by our findings.
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