TY  - GEN
A1  - Araujo Sousa, Carolina
N2  - Keeping balance is essential for the survival of mammals. When facing challenges, these animals rely on a neural system that promptly coordinates physiological and behavioral adaptations that are triggered to maintain homeostasis. In such context, neuroactive peptides, including neuropeptides and some peptide hormones, have been proposed to play an important role in the modulation of neural activity. These molecules have been implicated in the control of several processes, such as sleep, reproduction, and feeding, and are also believed to influence thermoregulation. The mammalian core body temperature (Tcore) is maintained by the thermoregulatory circuitry, which is orchestrated by the preoptic area (POA) of the hypothalamus. Different lines of evidence have suggested a role for neuroactive peptides in thermal balance, especially acting at the POA. Despite this, the molecular mechanisms that modulate Tcore during thermal challenges remain unclear.

Here, to investigate which neuroactive peptides are released at the level of the POA during thermal challenges, an unbiased screening of samples collected in vivo from male mice was performed. For this, first, to enrich neuroactive peptide detection, an optimized protocol was established for the in vivo sampling and the sample preparation for liquid chromatography and tandem mass spectrometry (LC/MS-MS) analysis. Next, the optimized protocol was applied on samples collected from the POA of freely behaving adult male mice during three different types of thermal stimuli. These included the chemogenetic activation of a subpopulation of preoptic thermoregulatory neurons expressing the vesicular transporter VGLUT2 (POAVGLUT2), which induced hypothermia, and the ambient warm and cold temperature stimulation. The results suggested that, in total, peptides deriving from 18 neuroactive peptide precursors were detected to be differentially released at the mouse POA during thermal challenges. Among these precursors and respective peptides, somatostatin and secretogranin 1 were differentially detected in samples collected during the stimulation of POAVGLUT2 neurons compared to the control group. Additionally, in comparison to control conditions, the results suggest a differential release of peptides from the precursors of orexins, nociceptin, and nucleobindin 1 in warm-exposed mice, as well as, thyrotropin-releasing hormone (TRH), and diazepam binding inhibitor (DBI) in animals peripherally stimulated with cold. Moreover, the verification of the unbiased screening focused on two candidates, orexin and adiponectin. For both, in vivo samples collected either during warm or cold peripheral stimulation were evaluated with ELISA. In addition, further experiments investigated a potential role of orexins in thermoregulation, by focusing on the POA distribution of orexin receptor 2, the influence of orexin-A on preoptic neurons, and the injection of orexin receptor antagonists into the POA. Results of these experiments may have provided further evidence for the engagement of pro-orexin derived peptides in Tcore control. Additional studies are required to define these and the other peptides as modulators of preoptic thermoregulation. Nonetheless, the list of candidates of thermoregulatory peptides provided by this thesis could contribute to a better comprehension of the molecular control of POA during adaptation to thermal challenges. Given the vital importance of maintaining the Tcore in mammals, such candidates could potentially also be implicated in health and disease.
Y1  - 2023///
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/31696/
ID  - heidok31696
AV  - public
TI  - Analysis of neuroactive peptides on mouse hypothalamic thermoregulation
CY  - Heidelberg
ER  -