Prosomeric Hypothalamic Distribution of Tyrosine Hydroxylase Positive Cells in Adolescent Rats
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Frontiers
Materia
POMC Hypothalamic dopamine Terminal hypothalamus Peduncular hypothalamus Acroterminal hypothalamus Arcuate nucleus Paraventricular nucleus A13 group
Date
2022-05-06Referencia bibliográfica
Bilbao MG... [et al.] (2022) Prosomeric Hypothalamic Distribution of Tyrosine Hydroxylase Positive Cells in Adolescent Rats. Front. Neuroanat. 16:868345. doi: [10.3389/fnana.2022.868345]
Sponsorship
State Research Agency (AEI); European Commission PGC2018-098229-B-100; Fundacion Seneca 19904/GERM/15; Spanish GovernmentAbstract
Most of the studies on neurochemical mapping, connectivity, and physiology in the
hypothalamic region were carried out in rats and under the columnar morphologic
paradigm. According to the columnar model, the entire hypothalamic region lies
ventrally within the diencephalon, which includes preoptic, anterior, tuberal, and
mamillary anteroposterior regions, and sometimes identifying dorsal, intermediate,
and ventral hypothalamic partitions. This model is weak in providing little or no
experimentally corroborated causal explanation of such subdivisions. In contrast, the
modern prosomeric model uses different axial assumptions based on the parallel
courses of the brain floor, alar-basal boundary, and brain roof (all causally explained).
This model also postulates that the hypothalamus and telencephalon jointly form
the secondary prosencephalon, separately from and rostral to the diencephalon
proper. The hypothalamus is divided into two neuromeric (transverse) parts called
peduncular and terminal hypothalamus (PHy and THy). The classic anteroposterior (AP)
divisions of the columnar hypothalamus are rather seen as dorsoventral subdivisions
of the hypothalamic alar and basal plates. In this study, we offered a prosomeric
immunohistochemical mapping in the rat of hypothalamic cells expressing tyrosine
hydroxylase (TH), which is the enzyme that catalyzes the conversion of L-tyrosine to
levodopa (L-DOPA) and a precursor of dopamine. This mapping was also combined
with markers for diverse hypothalamic nuclei [agouti-related peptide (Agrp), arginine
vasopressin (Avp), cocaine and amphetamine-regulated transcript (Cart), corticotropin
releasing Hormone (Crh), melanin concentrating hormone (Mch), neuropeptide Y
(Npy), oxytocin/neurophysin I (Oxt), proopiomelanocortin (Pomc), somatostatin (Sst),
tyrosine hidroxilase (Th), and thyrotropin releasing hormone (Trh)]. TH-positive cells
are particularly abundant within the periventricular stratum of the paraventricular and
subparaventricular alar domains. In the tuberal region, most labeled cells are found in
the acroterminal arcuate nucleus and in the terminal periventricular stratum. The dorsal
retrotuberal region (PHy) contains the A13 cell group of TH-positive cells. In addition,
some TH cells appear in the perimamillary and retromamillary regions. The prosomeric model proved useful for determining the precise location of TH-positive cells relative to
possible origins of morphogenetic signals, thus aiding potential causal explanation of
position-related specification of this hypothalamic cell type.