Cholinergic neurotransmission in the hippocampus of aged rats: influence of L-alpha-glycerylphosphorylcholine treatment.

The influence of aging and of L-alpha-glycerylphosphorylcholine (GFC) treatment on the acetylcholine synthesizing and degradating enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) and on cholinergic muscarinic M-1 and M-2 receptors were assessed in the hippocampus using immunocytochemical, histochemical and radioligand binding techniques, respectively. The investigation was performed on male Wistar rats of 2 months (young), 12 months (adult), and 27 months (old). Oral GFC was given at the dose of 100 mg/Kg/day from the 21st to the 27th month of age. ChAT revealed the highest immunostaining in the hippocampus of adult rats followed by young and old animals. The highest expression of AChE reactivity was noticeable in the hippocampus of adult rats followed by old and young animals. Treatment with GFC restored in part ChAT immunoreactivity and AChE reactivity in the hippocampus of aged rats. Muscarinic M-1 and M-2 receptors were labeled with [3H]-pirenzepine and [3H]-AF-DX-116 respectively. The density of M-1 muscarinic receptors decreased with age, whereas M-2 muscarinic receptors did not change. GFC treatment countered in part the loss of M-1 receptors in old rats and was without effect on M-2 receptors.