Functional in vivo interaction between growth hormone and dopamine systems are correlated to changes in striatal somatostatin levels as detected by voltammetry.
The effects of growth hormone (GH) and somatomedin C (SmC), as well as those of apomorphine, dopamine (DA) agonist, or haloperidol (DA antagonist), upon the size of striatal voltammetric peaks 2 and 5 were investigated. Local intrastriatal injections of GH or SmC were followed by an increase in the height of both peak 2 (corresponding to the oxidation of extracellular dihydrophenylacetic acid, DOPAC, a metabolite of DA) and peak 5 (which may represent the oxidation of striatal extracellular somatostatin, SRIF). Treatment with haloperidol also increased the size of the striatal catechol peak but was responsible for a reduction of the neuropeptidergic signal. By contrast, apomorphine determined a decrease in striatal peak 2 (DOPAC) while increasing the levels of peak 5 (SRIF). The data further support the chemical identification of peak 5 at +800 mV as related to the in vivo oxidation of SRIF; in addition they indicate the presence of a functional relationship between this neuropeptide and the GH and DA systems in the striatum of anaesthetised rats.
Crespi
F
F
Department of Physiology and Pharmacology, Q.M.C., Nottingham University, UK.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001058:Apomorphine / Q000008:administration & dosage / Q000494:pharmacology; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D003543:Cysteamine / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology*; D004563:Electrochemistry / Q000379:methods; D004594:Electrophysiology / Q000379:methods; D013006:Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology*; D006220:Haloperidol / Q000008:administration & dosage / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000008:administration & dosage / Q000494:pharmacology*
D015102:3,4-Dihydroxyphenylacetic Acid; D013004:Somatostatin; D003543:Cysteamine; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D006220:Haloperidol; D001058:Apomorphine; D004298:Dopamine