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Prenatal Constant Light Exposure Induces Behavioral Deficits in Male and Female Rat Offspring: Effects of Prenatal
Tsveta Stoyanova1, Hristina Nocheva2, Zlatina Nenchovska1
1Institute of Neurobiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
Abstract:
Prenatal constant light exposure (CLE) impaired the anxiety response and circadian rhythms of testicular enzymes in adult male rat offspring, while melatonin corrected these deficiencies. However, the mechanism by which CLE induces these long-term behavioral consequences and the impact of melatonin system have not been examined. The aim of the present study was to investigate the effects of prenatal CLE and melatonin treatment on anxiety- and depression-like behaviors, and the melatonin system in male and female adult rat offspring. Six groups of male and female rat offspring (P60) exposed to either light/dark (LD) or CL regimes, and treated with vehicle or melatonin (10 mg/kg, s.c.) were evaluated for anxiety by open field (OF), elevated plus maze (EPM), and light/dark (LD) tests, and depressive-like response by splash test and sucrose preference test. Plasma adrenocorticotropic hormone (ACTH), corticosterone (CORT) and melatonin expression, and hippocampal MT1A and MT1b receptor expression were assessed by ELISA. Prenatal CLE induced behavioral deficits and elevated plasma CORT levels, while melatonin levels, their circadian rhythmicity, and hippocampal MT receptor expression were not altered in male and female offspring in the CLE regime. However, prenatal melatonin treatment corrected behavioral deficits in a sex-specific manner by up-regulating hippocampal MT receptors, even without altering systemic melatonin levels or normalizing CORT in either sex. The results of this study suggest critical insights into how prenatal environmental factors and therapeutic interventions shape physiological and behavioral outcomes.
Insights
Prenatal constant light exposure causes anxiety and depression in rat offspring. Melatonin treatment corrects these behaviors by up-regulating brain melatonin receptors, offering therapeutic insights.
Area of Science:
- Neuroscience
- Endocrinology
- Behavioral Biology
Background:
- Prenatal constant light exposure (CLE) disrupts circadian rhythms and behavior in offspring.
- The underlying mechanisms and the role of the melatonin system remain unclear.
Purpose of the Study:
- To investigate the effects of prenatal CLE and melatonin on anxiety- and depression-like behaviors.
- To examine the impact on the melatonin system in adult male and female rat offspring.
Main Methods:
- Rats were exposed to light/dark (LD) or CLE, with or without melatonin treatment.
- Behavioral tests (open field, elevated plus maze, light/dark, splash, sucrose preference) were used.
- Plasma hormones (ACTH, corticosterone, melatonin) and hippocampal MT receptor expression were measured.
Main Results:
- Prenatal CLE induced behavioral deficits and elevated corticosterone.
- Melatonin levels and hippocampal MT receptor expression were not altered by CLE.
- Prenatal melatonin treatment ameliorated behavioral deficits sex-specifically by up-regulating MT receptors.
Conclusions:
- Prenatal CLE negatively impacts offspring behavior and physiology.
- Melatonin acts via hippocampal MT receptors to correct these deficits, independent of systemic melatonin levels.
- This highlights the influence of prenatal environment and melatonin signaling on long-term outcomes.
