ABSTRACT: Photoperiod regulates genes encoding melanocortin 3 and serotonin receptors, and secretogranins expressed in the dmpARC of the Siberian hamster
Project description:The mechanism(s) involved in the regulation of the seasonal-appropriate body weight of the Siberian hamster is currently unknown. We have identified photoperiodically regulated genes including VGF in a sub-region of the arcuate nucleus termed the dorsomedial posterior arcuate (dmpARC). Gene expression changes in this nucleus so far account for a significant number of those reported as photoperiodically regulated and are therefore likely to contribute to seasonal physiological responses of the hamsters. The present study was conducted to identify additional genes expressed in the dmpARC regulated by photoperiod that could be involved in regulating the activity of this nucleus with respect to seasonal physiology of the Siberian hamster. Using laser capture microdissection coupled with a microarray analysis and a candidate gene approach, we have identified in the dmpARC several photoperiodically regulated genes that are known to have roles in secretory and intracellular signaling pathways. These include secretogranin III (SgIII) and SgVI (secretory pathway), melanocortin 3 receptor (MC3-R) and serotonin (5-HT) receptors 2A and 7 (signaling pathway), all of which increase in expression in short photoperiod. The spatial relationship between receptor signaling and potential secretory pathways was investigated by dual in situ hybridization, which revealed that 5-HT2A and 5-HT7 receptors are expressed in neurons expressing VGF mRNA and that a sub-population (approximately 40%) of these neurons express MC3-R. These gene expression changes in dmpARC neurons may reflect the functional requirement of these neurons for seasonal physiology responses of the hamster Samples were taken from 10 individual animals, 5 of which had lived under a short day (SD) photoperiod, the other 5 under a long day (LD) photoperiod. Each hybridisation compared a LD sample (labelled with Cy5) with a SD sample (labelled with Cy3).
Project description:The mechanism(s) involved in the regulation of the seasonal-appropriate body weight of the Siberian hamster is currently unknown. We have identified photoperiodically regulated genes including VGF in a sub-region of the arcuate nucleus termed the dorsomedial posterior arcuate (dmpARC). Gene expression changes in this nucleus so far account for a significant number of those reported as photoperiodically regulated and are therefore likely to contribute to seasonal physiological responses of the hamsters. The present study was conducted to identify additional genes expressed in the dmpARC regulated by photoperiod that could be involved in regulating the activity of this nucleus with respect to seasonal physiology of the Siberian hamster. Using laser capture microdissection coupled with a microarray analysis and a candidate gene approach, we have identified in the dmpARC several photoperiodically regulated genes that are known to have roles in secretory and intracellular signaling pathways. These include secretogranin III (SgIII) and SgVI (secretory pathway), melanocortin 3 receptor (MC3-R) and serotonin (5-HT) receptors 2A and 7 (signaling pathway), all of which increase in expression in short photoperiod. The spatial relationship between receptor signaling and potential secretory pathways was investigated by dual in situ hybridization, which revealed that 5-HT2A and 5-HT7 receptors are expressed in neurons expressing VGF mRNA and that a sub-population (approximately 40%) of these neurons express MC3-R. These gene expression changes in dmpARC neurons may reflect the functional requirement of these neurons for seasonal physiology responses of the hamster
Project description:Prolactin (PRL) is a multifunctional hormone involved in diverse physiological processes, including lactation, reproduction, growth, and renal function. However, its effects on kidney morphology in seasonal mammals remain largely unexplored. The Siberian hamster (Phodopus sungorus), a seasonally breeding species, exhibits distinct physiological adaptations in response to photoperiod-driven changes in prolactin levels. Previous studies have demonstrated that PRL treatment significantly increases kidney mass, yet the underlying molecular mechanisms remain unclear. This study aimed to investigate the impact of PRL on kidney morphology and the associated molecular pathways. Histological analysis using Hematoxylin and Eosin (H&E) staining revealed that PRL treatment significantly increased convoluted tubule width (CTW). To elucidate the molecular basis of these morphological changes, transcriptome analysis was performed, identifying 19 significantly enriched pathways that were negatively correlated with CTW. These findings provide novel insights into the role of PRL in regulating seasonal kidney morphology and highlight key molecular pathways involved in this process.Our results contribute to a deeper understanding of PRL’s role in renal adaptations to seasonal changes, paving the way for future research into the endocrine regulation of kidney structure and function in seasonal mammals.
Project description:Seasonal morphological brain plasticity plays a key role in driving adaptive behavioural responses. Structural changes in the brain including the hippocampus and amygdala (nucleus taeniae in birds), across photoperiods are thought to underlie seasonal shifts in emotional state. For humans, this includes manifestations of short photoperiod seasonal affective disorder (SAD). While morphological brain changes are well documented, the associated transcriptomic dynamics remain poorly understood. Here, we examined the transcriptomes of the hippocampus and amygdala or nucleus taeniae in two highly photoperiodic species, the Siberian hamster (Phodopus sungorus) and the Japanese quail (Coturnix japonica), to identify transcriptomic changes underpinning seasonal shifts in emotional state. Hamsters and quail exhibited robust physiological changes between long and short photoperiod treatment. Under short photoperiod, hamsters displayed anxiety-like behaviour (increased grooming) in the open field test, consistent with a SAD-like phenotype. Transcriptomic analysis of the amygdala in hamsters identified 76 significantly differentially expressed (DE) transcripts (including transthyretin, TTR) and prolactin receptor, PRLR as differentially expressed, but not significantly. In the quail nucleus taeniae, we found 54 DE transcripts (including tenascin-C, TNC). In the hamster hippocampus, 14 DE transcripts were found, including mahogunin ring finger-1 (MGRN1), and 31 in the quail hippocampus, including eyes absent-2 (Eya2). These findings provide novel insights into the transcriptomic mechanisms underpinning seasonal affective states and suggest conserved roles for prolactin and thyroid hormone signalling in mediating seasonal changes in physiology and affective behaviour, particularly in the Siberian hamster.