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Further Characterization of the Long‐Term Effect of RU24722 on Tyrosine Hydroxylase in the Rat Locus Coeruleus
Author(s) -
Schmitt Pascal,
RenyPalasse Véronique,
Bourde Odile,
Garcia Christine,
Pujol JeanFrancois
Publication year - 1993
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1993.tb13636.x
Subject(s) - locus coeruleus , tyrosine hydroxylase , endocrinology , medicine , hypophysectomy , catecholaminergic , adrenalectomy , tyrosine , hormone , chemistry , biology , dopamine , central nervous system , biochemistry
Recent data have indicated that the long‐lasting increase in tyrosine hydroxylase (TH) protein could be differently expressed in the anterior and posterior locus coeruleus (LC) after a single intraperitoneal injection of RU24722, which has been proposed as a potent activator of catecholaminergic systems. In the present study, we have evaluated the dose and time course responses and the effect of a repeated treatment with RU24722 at 3‐day intervals on TH protein level in the anterior and posterior rat LC. The results showed that RU24722 induces a long‐lasting increase of TH protein level in the anterior and posterior LC that was maximal 3 days following a single injection of 30 mg/kg. The increase in TH protein was maintained at a constant level after repeated administrations of RU24722 at 3‐day intervals. Furthermore, we have investigated whether the effect of the drug on TH protein could be modulated via several hormonal systems. The long‐term increase of TH steady‐state content after RU24722 was still observed 15 days after castration, adrenalectomy, hypophysectomy, and thyroidectomy. The initial steady‐state TH protein level was significantly higher in the anterior LC of thyroid‐ or hypophysectomized and in the posterior LC of hypophysectomized rats. However, this increase was reversed when animals were housed at 28°C.