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Indirect evidence suggests that glucocorticoid hormones may act through cellular receptors to play a neuromodulatory role in the teleost CNS. We now report our findings on the use of [3H]dexamethasone (DEX) to identify hypothalamic glucocorticoid receptors (GRs) in juvenile rainbow trout, Oncorhynchus mykiss. Hypothalamic cytosol was incubated with [3H]DEX(More)
The purpose of the present investigation was to examine the receptor specificity of dopamine inhibition of gonadotropin (GtH) and alpha-melanocyte-stimulating hormone (alpha-MSH) release from the goldfish (Carassius auratus) pituitary in vitro. Pars distalis (PD) and neurointermediate lobe (NIL) fragments of the goldfish pituitary were superfused in vitro(More)
Dopamine acts directly on the pituitary to modulate gonadotrophin (GtH) secretion in goldfish (Carassius auratus). In the light of this important role for dopamine in the regulation of goldfish reproduction, this investigation was designed to evaluate the receptor specificity of this dopamine inhibition and to describe the use of domperidone, a specific(More)
Seasonal variations in the serum concentrations of gonadotropin (GtH) and the serum GtH response to intraperitoneal injection of domperidone, a specific dopamine receptor antagonist, were examined in goldfish. In addition, the effects of in vivo treatment of goldfish with a superactive analog of salmon gonadotropin-releasing hormone (sGnRH-A) and(More)
Gonadal steroids in the salmonid brain, acting through cellular receptors, may be responsible for the modulation of neuronal activity and organization of reproductive behaviors. We report our findings on the use of [3H]17beta-estradiol (E2) to identify intracellular estrogen receptors (ERs) in the hypothalamus of juvenile rainbow trout, Oncorhynchus mykiss.(More)
Plasma levels, peripheral metabolism and extrathyroidal in vivo production of reverse T3 (rT3 = 3,3',5'-triiodo-L-thyronine) were studied in rainbow trout at 12 degrees C. Plasma rT3 levels (less than 40 pg/ml) corresponded to the detection limit of the radioimmunoassay. By in vitro analysis, a high proportion (0.95%) of rT3 added to plasma existed in the(More)
An immersion protocol was established for chronically administering thyroid hormone to fish. Rainbow trout were immersed in solutions of 3,5,3'-triiodo-L-thyronine (T3) at 11 degrees C for various periods. Most plasma T3 adjustment occurred by 24 hr and within 5 days consistent plasma T3 levels were observed. Availability of unoccupied hepatic nuclear(More)