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After stereotaxically injecting male mice of the inbred strains C57BL/6 and DBA/2 with two doses of methylscopolamine or with two doses of neostigmine into the left dorsal hippocampus, the frequencies of the exploratory acts rearing, leaning, and sniffing carried out in a novel environment were recorded. At the lower dose-level, the anticholinergic drug tended to augment exploration in strain DBA and to reduce it in strain C57BL; the two doses of anticholinesterase diminished the scores in both genotypes. From these data it is concluded that the hippocampus contains a cholinergic mechanism which regulates exploratory behaviour and which is genetically controlled. [ABSTRACT FROM AUTHOR]

Peripheral administration of scopolamine tended to reduce the frequencies of three exploratory acts in mouse strain C57BL/6 and to increase them in strain DBA/2, whereas methylscopolamine was ineffective. Physostigmine diminished these exploratory scores in both genotypes, whereas neostigmine had no such effects. These observations support the hypothesis of a genetically controlled cholinergic mechanism which is located in the brain and which facilitates exploratory behaviour in mice. [ABSTRACT FROM AUTHOR]

In this psychopharmacogenetic study, male mice of strains C57BL/6, DBA/2, and D2B6F received injections with four doses of the anticholinergic scopolamine and with four doses of the anticholinesterase eserine. The frequencies of four different exploratory forms of behaviour carried out in a novel environment were subsequently measured. Both scopolamine and eserine reduced the scores of object-sniffing, leaning against the wall and rearing in the otherwise high-scoring C57BL and F animals. In DBA mice, which rate low when undrugged, scopolamine caused opposite effects and eserine similar effects with regard to these acts. From these observations it is concluded that there exists a cholinergic mechanism, operating efficiently in strain C57BL and less so in strain DBA, which facilitates certain exploratory behaviours and the action of which is controlled by genetic factors. [ABSTRACT FROM AUTHOR]