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The pineal affects life span in hamsters with heart disease
B H Natelson1, J E Ottenweller, W N Tapp
1VA Medical Center, and Department of Neurosciences, New Jersey Medical School, East Orange 07018, USA. bhn@nbunj.jvnc.net
Insights
Altering light-dark cycles impacts lifespan in cardiomyopathic hamsters. The pineal gland and melatonin, not testes, appear to mediate these effects, suggesting potential therapeutic avenues for heart failure.
Area of Science:
- Chronobiology
- Cardiovascular Research
- Endocrinology
Background:
- Cardiomyopathic hamsters (CMH) exhibit early-onset heart disease, progressing to congestive heart failure and premature death.
- Previous studies indicated that non-24-hour light-dark (LD) cycles can extend lifespan in CMH.
Purpose of the Study:
- To investigate the underlying mechanisms by which non-24-hour LD cycles influence longevity in CMH.
- To determine the roles of the pineal gland, melatonin, testes, and testosterone in mediating these effects.
Main Methods:
- CMH underwent orchidectomy, pinealectomy, or received melatonin treatment.
- Animals were exposed to either 1:23 or 1:23.6 LD cycles.
- Longevity and heart failure progression were monitored.
Main Results:
- Orchidectomy did not affect longevity but exacerbated heart failure in the 1:23.6 LD cycle.
- Pinealectomy in 1:23 LD cycles mimicked the lifespan changes observed in 1:23.6 LD cycles.
- Melatonin treatment in 1:23.6 LD cycles partially replicated the lifespan effects of 1:23 LD cycles.
Conclusions:
- The pineal gland and melatonin are likely involved in mediating the lifespan effects of non-24-hour LD cycles in CMH.
- Testes and testosterone do not appear to play a significant role in these effects.
- Inhibition of pineal function may offer benefits for congestive heart failure, warranting further investigation into treatment timing.
Abstract:
Cardiomyopathic hamsters (CMH) develop heart disease early in life which leads to congestive heart failure and death as these hamsters age. We have previously shown that living in constant light or other non-24-h light-dark (LD) cycles can increase longevity in these hamsters, and the current experiment examined potential mechanisms for this effect. Thus, CMH were orchidectomized, pinealectomized, or given melatonin treatment and then placed on either 1:23 or 1:23.6 LD cycles. Orchidectomy had no effect on longevity in either LD cycle, but in 1:23.6 it did lead to death with a greater degree of heart failure. On the other hand, pinealectomy of 1:23 CMH led to changes in life span similar to those produced by placing the hamsters in 1:23.6. Moreover, melatonin implant treatment of CMH in 1:23.6 led to changes in life span that were similar to those caused by life in 1:23, at least over the first half of the survival curves. Thus, it appears that the pineal gland and melatonin may be involved in mediating the effects of non-24-h LD cycles, whether these effects are beneficial or detrimental. In addition, the testes and testosterone appear to have no role in mediating these effects. These data suggest that inhibition, rather than stimulation, of pineal function might be beneficial for those with congestive heart failure, but further experiments are necessary to clarify when during the disease process potential treatments might be helpful.