Akademik Veri Yönetim Sistemi
36th ECNP Congress, Barcelona, İspanya, 07 Ekim 2023, ss.1-2
Background: Lipopolysaccharide (LPS) is a bacterial toxin that increases the production of inflammatory cytokines. Leptin is a hormone that affects a variety of physiological processes including hunger, food consumption, energy expenditure, and reproduction. It is also a cytokine released during LPS-induced inflammation, along with other proinflammatory cytokines. Animal studies have shown that LPS and proinflammatory cytokines increase leptin expression. Another hormone that is effective in the immune system response triggered by LPS is melatonin released from the pineal gland. LPS increases melatonin production. Because of its effects on the immune system, LPS may as a result alter the rhythm of melatonin production.
Methods: Adult male Syrian hamsters (Mesocricetus auratus) were obtained from the hamster colony of the Hamster and Gerbil unit of Çanakkale Onsekiz Mart University. Animals (3 months old, 100-110 g) were subjected to 16 L:8D photoperiod. All lighting was provided by cool-white, fluorescent tubes (200 lux). Animals were housed at a room temperature of 22 ± 2°C in air-ventilated rooms. They had access to food and water ad libitum. The experimental procedures in this study followed the guidelines of Canakkale Onsekiz Mart University and were approved by the Institutional Animal Care and Use Committee (permit no: 2021/07-01). There were four different experimental groups in the study; control, pinealectomy, pinealectomy + LPS injection, and LPS injection only. LPS was injected intraperitoneally at a dose of 1mg/kg once a week at 20:00 h. 1.0 mL of blood was drawn from the orbital sinus of each animal's eye once a week at noon and at midnight. The experiments lasted three weeks. Hormone analyses were performed using the Melatonin and Leptin ELISA kit. Significance was measured at p<0.05.
Results: Serum leptin levels increased only in the LPS injection group when compared to the other experimental groups (p<0.05). LPS administered at 20:00 h increased serum leptin levels more during the light than during the dark portions of the day (p<0.05). After administering LPS to pinealectomized animals, however, there was no significant difference in leptin levels between the light and dark phases (p>0.05). Only the serum melatonin level of the LPS group increased compared to the other experimental groups (p<0.05). The daytime melatonin level after LPS application in pinealectomized animals did not differ from the group that received only LPS injections (p>0.05).
Conclusion: Compared to the control group that received no treatment, the LPS group experienced higher levels of leptin and melatonin as well as altered night and day rhythms. It is possible to hypothesize that the Suprachiasmatic nucleus (SCN), which plays the primary role in the development of these circadian hormonal rhythms, was impacted by the inflammation because it altered the hormonal rhythms. For instance, a study suggests that applying LPS during the nighttime causes phase delays. Therefore, it is crucial to investigate whether the SCN plays a role in mediating the irregularities in hormonal rhythms caused by the application of LPS.