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Seasonal and Nutritional Fluctuations in the mRNA Levels of the Short Form of the Leptin Receptor (LRa) in the Hypothalamus and Anterior Pituitary in Resistin-Treated Sheep.

ABSTRACT: The short form of the leptin receptor (LRa) plays a key role in the transport of leptin to the central nervous system (CNS). Here, the resistin (RSTN)-mediated expression of LRa in the preoptic area (POA), ventromedial and dorsomedial nuclei (VMH/DMH),arcuate nucleus (ARC) and the anterior pituitary gland (AP)was analyzed considering the photoperiodic (experiment 1) and nutritional status (experiment 2) of ewes. In experiment 1, 30 sheep were fed normally and received one injection of saline or two doses of RSTN one hour prior to euthanasia. RSTN increased LRa expression mainly in the ARC and AP during long days (LD) and only in the AP during short days (SD). In experiment 2, an altered diet for 5 months created lean or fat sheep. Twenty sheep were divided into four groups: the lean and fat groups were given saline, while the lean-R and fat-R groups received RSTN one hour prior to euthanasia. Changes in adiposity influenced the effect of RSTN on LRa mRNA transcript levels in the POA, ARC and AP and without detection of LRa in the VMH/DMH. Overall, both photoperiodic and nutritional signals influence the effects of RSTN on leptin transport to the CNS and are involved in the adaptive/pathological phenomenon of leptin resistance in sheep.

SUBMITTER: Biernat W

PROVIDER: S-EPMC8388769 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:During the winter, hibernating mammals undergo extreme changes in physiology which allow them to survive without access to food. These animals enter a state of torpor, which is characterized by a decreased metabolism, near-freezing body temperatures, and a dramatically reduced heart rate. The neurochemical basis of this regulation is largely unknown. Based on prior evidence suggesting that the peptide-rich hypothalamus plays critical roles in hibernation, we hypothesized that changes in specific cell-cell signaling peptides (neuropeptides and peptide hormones) underlie physiological changes during torpor/arousal cycles. To test this hypothesis, we used a mass spectrometry-based peptidomics approach to examine seasonal changes of endogenous peptides that occur in the hypothalamus and pituitary of a model hibernating mammal, the thirteen-lined ground squirrel (Ictidomys tridecemlineatus). In the pituitary, we observed changes in a number of distinct peptide hormones as animals prepare for torpor in October, exit torpor in March, and progress from Spring (March) to Fall (August). In the hypothalamus, we observed an overall increase in neuropeptides in October (pre-torpor), a decrease as the animal enters torpor, and an increase in a subset of neuropeptides during normothermic interbout arousals. Notable changes were observed for feeding regulatory peptides from NPY and proSAAS prohormones, opioid peptides from PENK, PDYN, and POMC prohormones, and a number of peptides without well-established functions. In contrast to transcriptome and antibody-based measurements, our mass spectrometry-based approach allowed the identification and measurement of the final processed forms of these peptides after extensive post-translational modifications. Overall, our study provides critical insight into changes in endogenous peptides in the hypothalamus and pituitary during mammalian hibernation that were not available from transcriptome measurements. Understanding the molecular basis underlying the hibernation phenotype may pave the way for future efforts to employ hibernation-like strategies for organ preservation, combating obesity, and treatments for stroke.

Dataset Information

Seasonal and Nutritional Fluctuations in the mRNA Levels of the Short Form of the Leptin Receptor (LRa) in the Hypothalamus and Anterior Pituitary in Resistin-Treated Sheep.

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