title: [Met5]Enkephalin content in brain regions of rats treated with lithium.
abstract: In rats, chronic treatment with lithium elicits a dose-dependent increase in the [Met5]enkephalin content of nucleus caudatus and globus pallidus. A single injection of lithium fails to change the striatal [Met5]enkephalin content. The increase in [Met5]enkephalin caused by chronic lithium is proportional to the serum lithium level. The extent of the increase in striatal [Met5]enkephalin content levels off at a value of about 250% that of untreated rats. This increase has a time latency of 2--3 days and reaches a plateau at 5 days. The increase that was present at 5 days was no longer evident if the treatment was continued for 2 weeks. Lithium also increases striatal [Leu5]enkephalin content by an extent equal to the increase of [Met 5]enkephalin. Based on the characteristics of the lithium-induced increase in [Met6]enkephalin content, it is proposed that lithium may reduce the rate of release of [Met5]enkephalin from the small enkephalinergic neurons that are intrinsic to the striatum; this action may be related to a change in the regulation of striatal neurons.
mesh_terms: D000679:Amygdala / Q000378:metabolism; D000818:Animals; D002421:Caudate Nucleus / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000378:metabolism*; D004745:Enkephalins / Q000378:metabolism*; D005917:Globus Pallidus / Q000378:metabolism; D008094:Lithium / Q000494:pharmacology*; D051381:Rats; D012688:Septum Pellucidum / Q000378:metabolism
chemical_list: D004723:Endorphins; D004745:Enkephalins; D008094:Lithium