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Postnatal development of the hypothalamic neuropeptide Y system
K L Grove1, S Allen, B E Grayson
1Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA. grovek@ohsu.edu
Neuroscience
|February 1, 2003
Summary
The early postnatal development of hypothalamic neuropeptide Y (NPY) projections and Y1 receptor expression is crucial for feeding circuits. Agouti-related protein (AgRP) serves as a reliable marker for arcuate NPY neurons during this critical period.
Area of Science:
- Neuroscience
- Developmental Biology
- Endocrinology
Background:
- Arcuate neuropeptide Y (NPY) neurons are key regulators of appetite in adults.
- The developmental origins of hypothalamic NPY fibers, particularly in early life, remain largely unknown.
- Agouti-related protein (AgRP) is co-expressed in a subset of arcuate NPY neurons.
Purpose of the Study:
- To investigate the postnatal development of arcuate NPY/AgRP neurons and their projections to the paraventricular nucleus (PVN) and dorsomedial hypothalamic nucleus (DMH).
- To examine the ontogeny of neuropeptide Y1 receptor (NPY1R) expression in these hypothalamic regions.
- To identify the sources of early postnatal NPY fibers in the PVN and DMH.
Main Methods:
- Immunohistochemistry and in situ hybridization were used to assess NPY, AgRP, and dopamine beta-hydroxylase (DBH) expression and localization.
- Postnatal day (P) 2, P5-6, and P10-11 rat pups were analyzed.
- Colocalization studies identified the origins of NPY fibers.
Main Results:
- AgRP mRNA and protein were exclusively found in arcuate NPY neurons starting at P2, serving as a marker for these neurons.
- Arcuate NPY/AgRP fibers innervated the DMH and PVN significantly at P5-6 and P10-11, respectively.
- A subset of NPY fibers in the PVN at P2 originated from the brainstem (DBH-positive).
- Hypothalamic NPY1R protein expression dramatically changed during the first two postnatal weeks.
Conclusions:
- The early postnatal period is characterized by dynamic changes in the hypothalamic NPY system, including the development of arcuate NPY/AgRP projections and NPY1R expression.
- These developmental changes suggest a critical period for the formation of this feeding regulatory circuit.
- Further research is needed to determine if local NPY sources contribute to early hypothalamic NPY innervation before arcuate projections are established.