Tag Archives: fertility

Circadian biology: jet lag, mood, & potential role of BP regulatory peptides

There are enough connections here to suggest it’s an interesting rabbit hole.  Besides the effects of ARBs & desmopressin on mood and cognition, blood pressure regulation is not interesting <– fact.  But if it ties into fertility, circadian biology, and seasonal changes in how we should be doing things…

Way back in 1998 when I was graduating high school, Murphy and colleagues were screwing with “light-entrainable” and “food-entrainable” oscillators of circadian rhythmicity (1998).  They did this in two lines of rats, one with intact vasopressin signaling and one without.  With little mechanistic work, they showed vasopressin mediates circadian effects driven by light; and rats without vasopressin were more entrainable by meal timing.  N.B. in addition to the posterior pituitary, vasopressin is also found in the famous circadian light-regulated SCN neurons (Rosving 2010).

While it is speculated to play a role in social behaviors and sexual motivation, vasopressin is primarily known for its anti-hypotensive effects.  When plasma volume drops, vasopressin is secreted to decrease urinary water loss and increase blood pressure.  This is antagonized by alcohol, which is thought to be one reason why alcohol can dehydrate you.

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It’s paleo: Hypothyroidism impairs reproductive success in bitches.

Kisspeptin was discovered in Hershey, Pennsylvania, and was named after Hershey’s Kisses.  It has 776 pubmed citations going back to 2001, and may (or may not) play a key part integrating circannual reproduction patterns and seasonal thyroid function.

Kisspeptin was originally identified as a protein that inhibited breast cancer and melanoma.  This might also provide insight into the WHO’s recent declaration of shift work as a “probable” carcinogen.

Exhibit A. TSH restores a summer phenotype in photoinhibited mammals via the RF-amides RFRP3 and kisspeptin (Klosen 2013)

In this study, TSH infusion in short-day adapted hamsters (who are in winter non-breeding mode) induced summer phenotype & kisspeptin.  It also fattened them up a bit.  These TSH secreting neurons express melatonin receptors, but not those for TRH or T3 (Klosen 2002), so it is said to go something like this:Kisspeptin feedback diagram

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