Neuropeptides of the hypothalamic arcuate nucleus (ARC) regulate important homeostatic
and endocrine functions and also play critical roles in pubertal development. Altered
peptidergic and amino acidergic neurotransmission accompanying pubertal maturation
of the ARC are not fully understood. Here we studied the developmental shift in the
gene expression profile of the ARC of male mice. RNA samples for quantitative RT-PCR
studies were isolated from the ARC of day-14 infantile and day-60 adult male mice
with laser-capture microdissection. The expression of 18 neuropeptide-, 15 neuropeptide
receptor-, 4 sex steroid receptor and 6 classic neurotransmitter marker mRNAs were
compared between the two timepoints. Adult animals showed increased mRNA levels encoding
cocaine- and amphetamine-regulated transcript, galanin-like peptide, dynorphin, kisspeptin,
proopiomelanocortin, proenkephalin and galanin and reduced expression of mRNAs for
pituitary adenylate cyclase activating peptide, calcitonin gene-related peptide, neuropeptide
Y, substance P, agouti-related protein, neurotensin and growth hormone-releasing hormone.
From the neuropeptide receptors tested, melanocortin receptor-4 showed the most striking
(5-fold) increase. Melanocortin receptor-3 and the Y1 and Y5 neuropeptide Y receptors
increased 1.5-1.8-fold, whereas delta-opioid receptor and neurotensin receptor-1 transcripts
were reduced by 27 and 21%, respectively. Androgen-, progesterone- and alpha-estrogen
receptor transcripts increased by 54-72%. The mRNAs of glutamic acid decarboxylase
65, and 67, vesicular GABA transporter and choline acetyltransferase remained unchanged.
Tyrosine hydroxylase mRNA increased by 44%, whereas type-2 vesicular glutamate transporter
mRNA decreased by 43% by adulthood. Many of the developmental changes we revealed
in this study suggest reduced inhibitory and/or enhanced excitatory neuropeptidergic
drive on fertility in adult animals. (c) 2015 S. Karger AG, Basel.
