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| Author(s): |
Giovanna Zanetti
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2023-10-03 |
| Examining board members: |
Ana Maria de Lauro Castrucci;
Patrícia Reckziegel;
Patrícia Tachinardi Andrade Silva
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| Advisor: | Ana Maria de Lauro Castrucci; Maria Nathalia de Carvalho Magalhães Moraes Figueira Borges |
| Abstract | |
The opsins, proteins with seven transmembrane domains, are receptors specialized in sensing the light from prokaryotes to man. Undoing the view that opsins are exclusively light sensors, today it is accepted that opsins form a family of multi-functional molecules that have the potential to perceive temperature and light. In mammals, melanopsin is a retinal photopigment found in a subset of intrinsically photosensitive ganglion cells (ipRGCs), which play a role in synchronizing the central circadian pacemaker with the day-light cycle. Many peripheral tissues were found to express melanopsin, being the heart the organ with the greatest expression. The heart is responsible for producing and secreting hormones known as natriuretic peptides (NPs), which show increased serum concentration after cold challenges. In addition to the cardiac NP secretion, the influence of temperature on the expression of natriuretic peptide receptors in the brown adipose tissue has been established: mice challenged by low temperature release NPs by the activation of cardiac β1 adrenoceptors, NPs favor BAT thermogenesis as does the activation of β3 adrenoceptors in BAT. In this work, we investigated whether the metabolic changes triggered by cold involve activation of melanopsin directly in BAT or an indirect pathway that relies on the activation of melanopsin in the heart and consequent regulation of NP secretion. And if such events fluctuate throughout the day. Our results of O2 consumption and expired CO2 volume showed that Opn4 KO animals have a greater increase in their metabolism than WT animals, in order to guarantee thermoregulation facing the same cold challenge. Thermography data showed that Opn4 KO animals had a higher temperature in the BAT and inguinal region when compared to WT at 22°C, for greater heat production for thermal homeostasis. qPCR analyses showed that UCP1 transcripts are markedly elevated in both genotypes at 22°C compared to thermoneutrality and that OPN4 participates in the regulation of clock genes Per2, Bmal1, and Rev-erb in BAT when the animal was exposed to different temperatures. Through cardiac NP secretion and qPCR analysis of NP receptors, we demonstrated that OPN4 is important for the NP pathway rhythmicity, participating in the regulation of thermogenesis in BAT. (AU) | |
| FAPESP's process: | 21/01659-2 - Participation of melanopsin in the thermoregulation of mammals |
| Grantee: | Giovanna Zanetti |
| Support Opportunities: | Scholarships in Brazil - Master |