Abstract
The 24-h patterns of melatonin, PRL, and gonadotropins in male rats maintained under natural lighting conditions have been found to differ from the patterns in rats kept under artificial lighting. In the present experiments we studied the role of different daily illuminances as a possible causative factor for the variation of the hormonal patterns. Three groups of male rats were kept under artificial lighting conditions (12 h on/12 h off), where the daily illuminance was 550, 110 or 25 lux. After a 7-day adaptation period the pineal content of melatonin, the serum levels of LH, FSH and PRL, and the pituitary content of these hormones were measured by RIAs in samples taken at 10.00, 13.00, 22.00 and 01.00 h. The patterns of pineal melatonin were equal in all three groups. The variation of daily illuminance did not change the serum levels of LH, FSH and PRL or the pituitary content of the gonadotropins. However, the pituitary content of PRL during the light phase was inversely related to the illuminance. The results suggest that the intensity of daily lighting in the studied range does not affect the patterns of melatonin or gonadotropins, but the synthesis of prolactin may be significantly regulated by the daily illuminance level.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
