Growth hormone-induced stimulation of swimming and feeding behaviour of rainbow trout is abolished by the D-1 dopamine antagonist SCH23390

• The effects of GH on various types of behaviour in fish are well documented although the underlying mechanisms are not fully understood. In rainbow trout, an involvement of the brain dopaminergic system in mediating the behavioural effects of GH has been indicated, as GH can alter the brain doparninergic activity. To further examine the role of the dopaminergic system in the mediation of GH effects on locomotion and foraging, GH- and sham-implanted juvenile rainbow trout were injected with the selective D, dopamine antagonist SCH23390 or vehicle. Swimming and feeding activity was then studied by direct observation. Brains were thereafter sampled and analysed for the content of serotonin, dopamine and their metabolites in the hypothalamus, optic tecturn, cerebellum, telencephalon, and brain stem. GH increased swimming activity as well as feed intake, effects which were abolished by SCH23390. By itself, the antagonist did not affect behaviour, nor did it affect the brain monoamines. In contrast, treatment with GH, with or without SCH23390, decreased the content of the dopamine metabolite homovanillic acid (HVA) in the optic tecturn and the cerebellum, as well as the serotomin content (5-HT) in the optic tectum. It is concluded that the D-1 dopamine receptor of the dopaminergic system appears to be of importance in the mediation of the effects of GH on behaviour. (C) 2004 Elsevier Inc. All rights reserved.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

growth hormone

behaviour

dopamine

d-1-receptors

sch23390

locomotor activity

swimming

feeding

monoamines

homovanillic acid

teleost fish

eel anguilla-anguilla

locomotor-activity

receptor subtypes

atlantic salmon

antipredator behavior

molecular-cloning

social-dominance

brain monoamines

increases

vertebrates

growth hormone; behaviour; dopamine; D-1-receptors; SCH23390; locomotor activity; swimming; feeding; monoamines; homovanillic acid; teleost fish

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