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Titolo:
Effects of chronic bromocriptine treatment on tyrosine hydroxylase (TH) mRNA expression, TH activity and median eminence dopamine concentrations in ageing rats
Autore:
MohanKumar, PS; MohanKumar, SMJ; Quadri, SK; Voogt, JL;
Indirizzi:
Univ Kansas, Med Ctr, Dept Mol & Integrat Physiol, Kansas City, KS USA Univ Kansas Kansas City KS USA l & Integrat Physiol, Kansas City, KS USA Kansas State Univ, Coll Vet Med, Dept Diagnost Med & Pathobiol, Neuroendocrine Res Lab, Manhattan, KS 66506 USA Kansas State Univ Manhattan KS USA 66506 Res Lab, Manhattan, KS 66506 USA
Titolo Testata:
JOURNAL OF NEUROENDOCRINOLOGY
fascicolo: 3, volume: 13, anno: 2001,
pagine: 261 - 269
SICI:
0953-8194(200103)13:3<261:EOCBTO>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
CHRONIC HYPERPROLACTINEMIA; SUBSTANTIA-NIGRA; PITUITARY-TUMORS; PREOPTIC AREA; FEMALE RATS; PROLACTIN; NEURONS; RELEASE; NOREPINEPHRINE; NUCLEI;
Keywords:
bromocriptine; prolactin; TIDA; mammary tumour; ageing; oestrous cycle; HPLC;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: MohanKumar, PS Michigan State Univ, Coll Vet Med, Neuroendocrine Res Lab, A522 E Fee Hall, E Lansing, MI 48824 USA Michigan State Univ A522 E Fee Hall E Lansing MI USA 48824
Citazione:
P.S. MohanKumar et al., "Effects of chronic bromocriptine treatment on tyrosine hydroxylase (TH) mRNA expression, TH activity and median eminence dopamine concentrations in ageing rats", J NEUROENDO, 13(3), 2001, pp. 261-269

Abstract

The purpose of this study was to investigate the age-related changes in the responsiveness of tuberoinfundibular dopamine (TIDA) neurones to chronic hypoprolactinemia induced by treatment with bromocriptine, a dopamine receptor agonist, In one experiment, TIDA neuronal activity after acute hypoprolactinemia or exogenous prolactin was monitored by measuring tyrosine hydroxylase (TH) activity in the stalk median eminence of middle-aged cycling female rats (10-12 months), old constant oestrous rats (18-20 months) and old pseudopregnant rats (22-24 months). in another experiment, middle-aged cycling (10-12 months) rats were treated with bromocriptine for 6 or 12 months. TH activity was measured in the stalk median eminence, TH mRNA levels weremeasured in the arcuate nucleus and dopamine concentrations were measured in the arcuate nucleus and median eminence. Responsiveness of TIDA neuronesto exogenous prolactin and to the withdrawal of bromocriptine in these rats was also tested. While the TIDA neurones in all three age groups responded to acute hypoprolactinemia by showing a reduction in TH activity, older rats failed to respond to exogenous prolactin administration, In contrast, chronic hypoprolactinemia for 12 months enabled the rats to retain TIDA neuronal responsiveness to exogenous prolactin, It also decreased TIDA neuronalfunction as measured by dopamine concentrations in the median eminence, THactivity in the stalk median eminence and TH mRNA in the arcuate nucleus of ageing rats. The restoration of the responsiveness of these neurones to prolactin stimulation in older rats demonstrates for the first time that hypoprolactinemia produced by chronic bromocriptine treatment indeed provides a neuroprotective effect on TIDA neurones. These results indicate that maintaining a low level of neuronal activity by lowering prolactin levels may be a contributing factor in retaining the plasticity of TIDA neurones.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/01/20 alle ore 18:56:28