Several hormones play a role in tear production, making a single definitive answer incomplete. While no single hormone is solely responsible, serotonin and prolactin are significantly involved in regulating tear secretion.
The Role of Serotonin
Research indicates that serotonin, a neurotransmitter also functioning as a hormone, plays a crucial role in tear production. A study published in Scientific Reports found that the serotonin type 3a receptor in the lacrimal gland (tear-producing gland) is involved in tear secretion via intracellular calcium mobilization. This highlights serotonin's direct influence on the process. https://www.nature.com/articles/s41598-017-06022-4 This hormonal regulation works in conjunction with the autonomic nervous system to control tear flow.
The Role of Prolactin
Prolactin, a hormone primarily known for its role in milk production, has also been linked to tear production. Studies suggest that emotional tears contain elevated levels of prolactin, implicating its involvement in the hormonal response to emotional stimuli that trigger crying. https://www.nytimes.com/2011/01/04/science/04qna.html https://psychcentral.com/blog/the-science-of-tears
Other Contributing Factors
While serotonin and prolactin are prominent, other hormones likely influence tear production to a lesser extent. Testosterone, for instance, may inhibit crying, suggesting an indirect role in regulating tear secretion. https://www.apa.org/monitor/2014/02/cry Furthermore, the removal of stress hormones through tears might imply a secondary influence of these hormones on tear volume. https://www.health.harvard.edu/blog/is-crying-good-for-you-2021030122020
In summary, tear production is a complex process regulated by multiple hormonal and neurological pathways. While serotonin and prolactin stand out as key players, a complete understanding requires considering the interplay of various hormonal and nervous system interactions.
