Mauritio
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- Joined
- Feb 26, 2018
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Photobiomodulation/Photoperiodism and the influence of light on thyroid status
Here is a collection of studies showing how the amount of light we receive every day infleunces our body's metabolism. Our bodies anticipate the season by amount of light we get and changes the metabolism accordingly. Obviously a "summer metabolism" would be more favorable, so there is a way to use this information to suggest to your body that it is summer.
1. - Short light exposure leads to lower T3 levels
- Supplementing T3 can at least partially restore the "summer metabolism" and make up for low light expusre
"The expression of the gene encoding type III deiodinase (Dio3) and Dio3 activity in vivo (catabolism of T(4) and T(3)) is dynamically and temporally regulated by photoperiod, consistent with the loss of hypothalamic T(3) concentrations under short photoperiods. Chronic replacement of T(3) in the hypothalamus of male hamsters exposed to short photoperiods, thus bypassing synthetic or catabolic deiodinase enzymes located in cells of the ependyma of the third ventricle, prevented the onset of short-day physiology: hamsters maintained a long-day body weight phenotype and failed to undergo testicular and epididymal regression. However, pelage moult to a winter coat was not affected. Type II deiodinase gene expression was not regulated by photoperiod in these hamsters. Collectively, these data point to a pivotal role for hypothalamic DIO3 and T(3) catabolism in seasonal cycles of body weight and reproduction in mammals."
- Hypothalamic thyroid hormone catabolism acts as a gatekeeper for the seasonal control of body weight and reproduction - PubMed
2. - Ligth increases T4 to T3 conversion
- Hypothalamic T3 levels are 10 times lower in short days vs. long days, but plasma levels stay the same
"Here we report that expression in the MBH of the gene encoding type 2 iodothyronine deiodinase (Dio2), which catalyses the intracellular deiodination of thyroxine (T4) prohormone to the active 3,5,3'-triiodothyronine (T3), is induced by light in Japanese quail.
- Light-induced hormone conversion of T4 to T3 regulates photoperiodic response of gonads in birds - PubMed
3. Long days cause TSH increase,which causes increase in DIO2 and T3
"The switch to long days causes melatonin-responsive cells in the pars tuberalis (PT) of the anterior pituitary to increase production of thyrotrophin (TSH). This acts locally on TSH-receptor-expressing cells in the adjacent mediobasal hypothalamus, leading to increased expression of type II thyroid hormone deiodinase (DIO2). DIO2 initiates the summer response by increasing hypothalamic tri-iodothyronine (T3) levels. "
- Ancestral TSH mechanism signals summer in a photoperiodic mammal - PubMed
4. DIO3, wich catabolizes T3 is decreased by long days and increased by short ones.
...type 3 deiodinase. Levels decreased after exposure to long days, but increased under short days."
5. - Again: long days increase TSH, drastically. A 700 fold increase after 30d ,why? DOI2 also increases which might balance the patholgical effects of TSH, but the increase is a lot smaller.
- T3 and T4 hypothalamic levels stay unchanged in long and short days
- Melatonin basically changes the long day into a short day metabolism
- Thyroid Hormone Signalling Genes Are Regulated by Photoperiod in the Hypothalamus of F344 Rats
Here is a collection of studies showing how the amount of light we receive every day infleunces our body's metabolism. Our bodies anticipate the season by amount of light we get and changes the metabolism accordingly. Obviously a "summer metabolism" would be more favorable, so there is a way to use this information to suggest to your body that it is summer.
1. - Short light exposure leads to lower T3 levels
- Supplementing T3 can at least partially restore the "summer metabolism" and make up for low light expusre
"The expression of the gene encoding type III deiodinase (Dio3) and Dio3 activity in vivo (catabolism of T(4) and T(3)) is dynamically and temporally regulated by photoperiod, consistent with the loss of hypothalamic T(3) concentrations under short photoperiods. Chronic replacement of T(3) in the hypothalamus of male hamsters exposed to short photoperiods, thus bypassing synthetic or catabolic deiodinase enzymes located in cells of the ependyma of the third ventricle, prevented the onset of short-day physiology: hamsters maintained a long-day body weight phenotype and failed to undergo testicular and epididymal regression. However, pelage moult to a winter coat was not affected. Type II deiodinase gene expression was not regulated by photoperiod in these hamsters. Collectively, these data point to a pivotal role for hypothalamic DIO3 and T(3) catabolism in seasonal cycles of body weight and reproduction in mammals."
- Hypothalamic thyroid hormone catabolism acts as a gatekeeper for the seasonal control of body weight and reproduction - PubMed
2. - Ligth increases T4 to T3 conversion
- Hypothalamic T3 levels are 10 times lower in short days vs. long days, but plasma levels stay the same
"Here we report that expression in the MBH of the gene encoding type 2 iodothyronine deiodinase (Dio2), which catalyses the intracellular deiodination of thyroxine (T4) prohormone to the active 3,5,3'-triiodothyronine (T3), is induced by light in Japanese quail.
- Light-induced hormone conversion of T4 to T3 regulates photoperiodic response of gonads in birds - PubMed
3. Long days cause TSH increase,which causes increase in DIO2 and T3
"The switch to long days causes melatonin-responsive cells in the pars tuberalis (PT) of the anterior pituitary to increase production of thyrotrophin (TSH). This acts locally on TSH-receptor-expressing cells in the adjacent mediobasal hypothalamus, leading to increased expression of type II thyroid hormone deiodinase (DIO2). DIO2 initiates the summer response by increasing hypothalamic tri-iodothyronine (T3) levels. "
- Ancestral TSH mechanism signals summer in a photoperiodic mammal - PubMed
4. DIO3, wich catabolizes T3 is decreased by long days and increased by short ones.
...type 3 deiodinase. Levels decreased after exposure to long days, but increased under short days."
5. - Again: long days increase TSH, drastically. A 700 fold increase after 30d ,why? DOI2 also increases which might balance the patholgical effects of TSH, but the increase is a lot smaller.
- T3 and T4 hypothalamic levels stay unchanged in long and short days
- Melatonin basically changes the long day into a short day metabolism
- Thyroid Hormone Signalling Genes Are Regulated by Photoperiod in the Hypothalamus of F344 Rats
