Medicine and Health Sciences Commons^™

Somatostatin Regulates Central Clock Function And Circadian Responses To Light, Deborah A.M. Joye, Kayla E. Rohr, Kimberlee Suenkens, Alissa Wuorinen, Thomas Inda, Madeline Arzbecker, Emma Mueller, Alec Huber, Harshida Pancholi, Murray G. Blackmore, Vania Carmona-Alcocer, Jennifer A. Evans

Biomedical Sciences Faculty Research and Publications

Daily and annual changes in light are processed by central clock circuits that control the timing of behavior and physiology. The suprachiasmatic nucleus (SCN) in the anterior hypothalamus processes daily photic inputs and encodes changes in day length (i.e., photoperiod), but the SCN circuits that regulate circadian and photoperiodic responses to light remain unclear. Somatostatin (SST) expression in the hypothalamus is modulated by photoperiod, but the role of SST in SCN responses to light has not been examined. Our results indicate that SST signaling regulates daily rhythms in behavior and SCN function in a manner influenced by sex. First, we …

Developmental Patterning Of Peptide Transcription In The Central Circadian Clock In Both Sexes, Vania Carmona-Alcocer, Lindsey S. Brown, Aisha Anchan, Kayla E. Rohr, Jennifer A. Evans

Biomedical Sciences Faculty Research and Publications

Introduction: Neuropeptide signaling modulates the function of central clock neurons in the suprachiasmatic nucleus (SCN) during development and adulthood. Arginine vasopressin (AVP) and vasoactive intestinal peptide (VIP) are expressed early in SCN development, but the precise timing of transcriptional onset has been difficult to establish due to age-related changes in the rhythmic expression of each peptide.

Methods: To provide insight into spatial patterning of peptide transcription during SCN development, we used a transgenic approach to define the onset of Avp and Vip transcription. Avp-Cre or Vip-Cre males were crossed to Ai9^+/+ females, producing offspring in which the fluorescent protein …

Vasopressin Resets The Central Circadian Clock In A Manner Influenced By Sex And Vasoactive Intestinal Polypeptide Signaling, Kayla E. Rohr, Thomas Inda, Jennifer A. Evans

Biomedical Sciences Faculty Research and Publications

Background/Aims: Circadian rhythms in behavior and physiology are programmed by the suprachiasmatic nucleus (SCN) of the hypothalamus. A subset of SCN neurons produce the neuropeptide arginine vasopressin (AVP), but it remains unclear whether AVP signaling influences the SCN clock directly.

Methods: Here, we test that AVP signaling acting through V1A and V1B receptors influences molecular rhythms in SCN neurons. V1 receptor agonists were applied ex vivo to PERIOD2::LUCIFERASE SCN slices, allowing for real-time monitoring of changes in molecular clock function.

Results: V1A/B agonists reset the phase of the SCN molecular clock in a time-dependent manner, with larger magnitude responses by …

Vasopressin Regulates Daily Rhythms And Circadian Clock Circuits In A Manner Influenced By Sex, Kayla Rohr, Adam Telega, Alexandra Savaglio, Jennifer A. Evans

Biomedical Sciences Faculty Research and Publications

Arginine vasopressin (AVP) is a neurohormone that alters cellular physiology through both endocrine and synaptic signaling. Circadian rhythms in AVP release and other biological processes are driven by the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. Loss of vasopressin signaling alters circadian behavior, but the basis of these effects remains unclear. Here we investigate the role of AVP signaling in circadian timekeeping by analyzing behavior and SCN function in a novel AVP-deficient mouse model. Consistent with previous work, loss of AVP signaling increases water consumption and accelerates recovery to simulated jetlag. We expand on these results to show that loss …

Reduced Vip Expression Affects Circadian Clock Function In Vip-Ires-Cre Mice (Jax 010908), Deborah A.M. Joye, Kayla Rohr, Danielle Keller, Thomas Inda, Adam Telega, Harshida Pancholi, Vania Carmonia-Alcocer, Jennifer A. Evans

Biomedical Sciences Faculty Research and Publications

Circadian rhythms are programmed by the suprachiasmatic nucleus (SCN), which relies on neuropeptide signaling to maintain daily timekeeping. Vasoactive intestinal polypeptide (VIP) is critical for SCN function, but the precise role of VIP neurons in SCN circuits is not fully established. To interrogate their contribution to SCN circuits, VIP neurons can be manipulated specifically using the DNA-editing enzyme Cre recombinase. Although the Cre transgene is assumed to be inert by itself, we find that VIP expression is reduced in both heterozygous and homozygous adult VIP-IRES-Cre mice (JAX 010908). Compared with wild-type mice, homozygous VIP-Cre mice display faster reentrainment and shorter …

In Synch But Not In Step: Circadian Clock Circuits Regulating Plasticity In Daily Rhythms, Jennifer A. Evans, M. R. Gorman

Biomedical Sciences Faculty Research and Publications

The suprachiasmatic nucleus (SCN) is a network of neural oscillators that program daily rhythms in mammalian behavior and physiology. Over the last decade much has been learned about how SCN clock neurons coordinate together in time and space to form a cohesive population. Despite this insight, much remains unknown about how SCN neurons communicate with one another to produce emergent properties of the network. Here we review the current understanding of communication among SCN clock cells and highlight a collection of formal assays where changes in SCN interactions provide for plasticity in the waveform of circadian rhythms in behavior. Future …