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Concurrent decrease of vasopressin and protein kinase Calpha immunoreactivity during the light phase in the vole
K Jansen1, E A Van der Zee, M P Gerkema
1Graduate School Behavioral and Cognitive Neurosciences, Groningen, The Netherlands. k.jansen@biol.rug.nl
Neuroscience Letters
|July 8, 1998
Summary
Circadian rhythms in voles involve vasopressin (AVP) and protein kinase Calpha. Neuron counts for both neuropeptides significantly decreased in the suprachiasmatic nucleus during the light phase.
Area of Science:
- Neuroscience
- Chronobiology
Background:
- The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals.
- Vasopressin (AVP) is a key neuropeptide within the SCN.
- Protein kinase Calpha is implicated as an intracellular signaling molecule.
Purpose of the Study:
- To investigate daily changes in AVP and protein kinase Calpha neuron populations within the SCN.
- To determine the temporal relationship between these neuropeptides and the light-dark cycle.
Main Methods:
- Immunohistochemistry was used to quantify AVP- and protein kinase Calpha-immunoreactive neurons.
- Cell counts were performed in the SCN of common voles.
- Voles were synchronized to a 12:12 hour light-dark cycle.
- Measurements were taken at two time points: zeitgeber time zero and zeitgeber time six.
Main Results:
- At zeitgeber time zero, mean counts were 2194 AVP neurons and 9897 protein kinase Calpha neurons.
- By zeitgeber time six, both AVP and protein kinase Calpha neuron counts decreased by approximately 40%.
- This concurrent reduction was most prominent in the dorsomedial SCN.
Conclusions:
- Daily fluctuations in AVP and protein kinase Calpha neurons occur in the SCN.
- These changes are linked to the light-dark cycle, suggesting a role in circadian regulation.
- Findings align with previous observations of elevated AVP release during the early light phase in other species.