Expression of tyrosine hydroxylase in magnocellular hypothalamic neurons of obese (fa / fa) and lean heterozygous (Fa / fa) Zucker rats.
In the magnocellular hypothalamic neurons (MCN) of normal rats, tyrosine hydroxylase (TH) is expressed in response to hyperosmotic stimulation and co-exists with vasopressin. The present study shows that both Zucker obese (fa / fa) and heterozygous lean (Fa / fa) rats express TH in MCN independently of an osmotic challenge. The lack of L-DOPA and aromatic-L-aminoacid decarboxylase in the MCN showed the absence of mechanisms necessary for catecholamine synthesis in these cells. Therefore, TH in MCN seems to be functionally inactive and is not involved in catecholamine abnormalities observed in these rats. All TH-immunoreactive MCN co-expressed vasopressin mRNA while a part of them co-expressed oxytocin mRNA. This suggests a mechanism of regulation of TH expression in MCN which is different in Zucker rats and in dehydrated normal rats.
Fetissov
S
S
Groupe de Neurobiologie des Regulations, IESGCA de Dijon, CNRS UPR 9054, Collège de France, Paris. fetissos@mailbox.hscsyr.edu
Marsais
F
F
Nicolaïdis
S
S
Calas
A
A
D000818:Animals; D005260:Female; D006579:Heterozygote; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000201:enzymology*; D009765:Obesity / Q000201:enzymology* / Q000473:pathology; D051381:Rats; D011924:Rats, Zucker; D013377:Substantia Innominata / Q000201:enzymology* / Q000473:pathology; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis*
D014446:Tyrosine 3-Monooxygenase