Histamine concentration in fetal rat brain is high at 17 days gestation but decreases sharply just before birth. Values subsequently increase to a maximum postnatal concentration 5 to 10 days after birth, and then steadily decline to low adult values by time of weaning. Spermidine follows a pattern similar to that of histamine but with a 24- to 48-hour lag. The developmental pattern for histamine in the central nervous system is different from that for other neural amines. It appears that the marked fetal and neonatal changes in brain histamine correlate best with periods of rapid cell proliferation and growth during brain maturation.

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Article abstractFourteen patients under treatment with levodopa for idiopathic Parkinson's disease were placed on a restricted methionine diet, 0.5 gm daily, for eight days. L-methionine, 1.5 gm three times a day, or placebo (lactose) was administered in a randomized, double-blind technique to seven patients. Seven on the low methionine regimen received placebo and three subjectively improved. Five of seven receiving a high I-methionine intake became worse. One patient exhibited a hypersexual, aggressive behavior without changes in clinical signs, and another became severely depressed. Patients regressed in gait, bradykinesia, tremor, and rigidity but returned to base line when I-methionine was discontinued. One patient deteriorated rapidly on I-methionine to a state even worse than that before levodopa therapy. We conclude that I-methionine may reverse the clinical effectiveness of levodopa in parkinsonism.

Livedo reticularis and peripheral edema often have been observed in patients receiving amantadine hydrochloride, suggesting alterations in the responsiveness of peripheral vessels. To investigate this possibility, five patients with Parkinson's disease who had either livedo reticularis or peripheral edema while being treated with amantadine (100 mg twice daily) were evaluated before and after the drug was discontinued. Finger and toe temperatures were significantly lower when patients received the drug than when it was discontinued, and plethysmographic studies showed increased flow in the lower limbs in three patients when the drug was stopped. It is concluded that amantadine therapy may be associated with peripheral vasoconstriction in some patients.