Brain choline acetyltransferase and muscarinic receptor sites, brain and liver cholinesterases in precocial Acomys cahirinus and altricial rat during post-natal development.

Brain choline acetyltransferase, acetylcholinesterase with its molecular forms, and muscarinic receptor sites, as well as liver total cholinesterases were evaluated during the first postnatal month in pups of a precocial (Acomys cahirinus) and altricial (rat) murid species. At birth the levels of brain cholinergic markers were higher in the Acomys than in the rat, but in adulthood the differences were smaller or even reversed. The postnatal increase up in the markers to weaning was considerably more pronounced in the rat. However, substantial variations in the patterns of development of the three cholinergic markers within and between species were observed. Liver cholinesterases were considerably higher in Acomys than in rats at all ages investigated. These and literature data are discussed in relation to postnatal, post-conception and post-organogenesis age of pups belonging to the two species. The variability of the ontogenetic patterns between the enzymes suggests that there is some biological control of individual rates of maturation and that it is necessary to be careful in broadly interpreting growth patterns across organs within the same species and across species.