Modification of avoidance behavior in 6-hydroxydopamine-treated rats by stimulation of central noradrenergic and dopaminergic receptors

Clonidine: New research in psychotropic drug pharmacology

“…Suppression of a previously learned conditioned avoidance response in rats produced by intraventricular administration of 6-hydroxydopamine was reported to be reversed by intraventricular administration of norepinephrine, dopamine, 1-dopa, or by intraperitoneal administration of amphetamine, phenylzine, desipramine, apomorphine, and ~lonidine.3O.~~ Pretreatment with spiroperidol prevented the recovery produced by the above drugs, however, clonidineinduced recovery was least affected. 31 The above studies demonstrate that clonidine has an effect on conditioned avoidance responding and support the suggestion for the involvement of both dopaminergic and noradrenergic systems in its mediation.…”

Modulation of Learning and Memory: Effects of Drugs Influencing Neurotransmitters

“…These results suggest a possible preferential role of DA, as opposed to NE, in the acquisition of avoidance responses, a view which has also found support in studies where intracisternal 6-0HDA infusions produced an apparent preferential depletion of whole-brain DA levels (Cooper et al, 1973;Howard et al, 1974). On the other hand, Lenard and Beer (1975b) have recently reported that the disruption of avoidance learning induced by intraventricular 6-0HDA infusion was reversed by administration of either DA or NE agonists. Furthermore, the use of intracerebral implantation of 6-0HDA as a tool for the specific destruction of CA neurons has been seriously questioned by recent morphological studies which have characterized the lesions produced by 6-0HDA as being largely nonspecific (Poirier et al, 1972;Sotelo et al, 1973;Evans et ai., 1975).…”

Pilocarpine and physostigmine attenuate spatial memory impairments produced by lesions of the nucleus basalis magnocellularis.

“…Rather, it appears that random occupancy of muscarinic receptor sites is sufficient for adequate functioning of brain regions that are innervated by the nBM. In this respect the nBM-cortical projection may be similar to the nigrostriatal dopaminergic system where directly acting dopamine receptor agonists are also known to reverse behavioral deficits produced by lesions of these dopaminergic neurons (Lenard & Beer, 1975; Ljungberg & Ungerstedt, 1976; Marshall & Gotthelf, 1979).…”