ISSN:
1420-9071
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The effects on dopamine (DA) metabolism, on3H-spiperone binding and on amphetamine-induced stereotypies of a variety of drugs with different actions on alpha1-and alpha2-noradrenergic (NA) receptors have been investigated. The preferential alpha2-antagonists yohimbine, rauwolscine, piperoxane and esproquin as well as the preferential alpha1-antagonists corynanthine and WB4101 increased homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the rat striatum, mesolimbic area, and cortex. Prazosine and clonidine tended to reduce HVA and DOPAC. The preferential alpha2-antagonists, tolazoline and RX-781094A, had no measurable effects on DA metabolism even at high doses. Those compounds which in comparable doses increased DA metabolism inhibited3H-spiperone binding in the hippocampus. The effects in the striatum and cortex were smaller and did not show a relation to those in hippocampus or on DA metabolism. Only the yohimbine alkaloids antagonized amphetamine-induced stereotypies. The results suggest that the effects on DA metabolism at least of yohimbine, rauwolscine, and corynanthine are related to their intrinsic antidopaminergic properties. The same might be true, although with a lesser degree of certainty, for piperoxane, esproquin, and WB4101. Since many of the tested compounds possessing alpha-antagonistic properties interacted with the DA system, a close molecular relationship between alpha-noradrenergic and DA receptors might be anticipated. The preference of these compounds for the hippocampal subtype of DA receptors might indicate a particular role of the latter in the regulation of DA metabolism. On the other hand, the antagonism against haloperidol's enhancing effect on DA metabolism by clonidine suggests a modulatory NA influence on DA transmission. The observation that clonidine reduced the effects of yohimbine and piperoxane to a lesser degree than that of haloperidol, is in agreement with this notion.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01959727
