2002 Fiscal Year Final Research Report Summary
The analysis of seasonality of stress-tolerance as indicators of testicular weight and body weight.
| Project/Area Number |
11610076
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
実験系心理学
|
|---|
| Research Institution | Shiga University |
|---|
Principal Investigator |
IBUKA Nobuo Shiga University, Faculty of Education, Prof., 教育学部, 教授 (70110757)
|
|---|
| Project Period (FY) |
1999 – 2002
|
| Keywords | seasonality / stress-tolerance / photoperiod / enriched environment / Syrian hamster / testis / body weight |
|---|
| Research Abstract |
A series of experiments were conducted to investigate the effects of stress coming from unpredictable food deprivation in Syrian hamsters under various experimental situations. In Exp.1 one group was exposed to decreasing photoperiod while the other group was exposed to increasing photoperiod from a neutral one when the animals were deprived of food at random on 50% days over the 12 weeks. The results clearly showed that unpredictable deprivation of food induced more detrimental effects on testicular weight and body weight under decreasing photoperiodic situation than increasing one. In other words stress-tolerance was weaker in autumlike photoperiodic situation than springlike one. In Exp.2 we have proposed the hypothesis that enriched environment will alleviate stress coming from unpredictable deprivation of food. Thus the animals living in the enriched environment show stronger tolerance for the stress than the ones in the conventional living environment. The enriched environment wa
… More
s produced in the cage by the introduction of such toys as activity wheel, L-shaped tunnel and ladder. The results showed that the testicular weight and body weight were heavier for the animals raised in the enriched environment than the ones in the conventional cages. The results also indicated that the detrimental effect of the development of testis and body weight was weaker for the animals in the enriched environment than the ones in the conventional environment when food was deprived at random over 12 weeks. That is, the stress tolerance was stronger for the animals raised in the enriched environment than in the conventional living condition. The working hypothesis was supported by these data. In Exp.3 we investigated the prior photoperiodic history in the LP → LP (LD18 : 6 → LD14 : 10)and LP → SP(LD14 : 10 → LD10 : 10) light regime on testicular weight and body weight. The decrease of photopeirod was the same 4 hours for the two situations. When food was deprived on 50% days over 12 weeks under the 2nd photoperiod, the testicular weight and body weight were more suppressed in the latter light regime than in the former one. The results showed that not the amount of decrease of the photoperiod but the transfer from LP to SP including the critical photoperiod is important for the detrimental effect of the development of testtis and body weight. Less
|
