Autoradiographic localization of [14C]8-S-adenosyl-L-homocysteine in rat brain

Adenosine analogs elevate N-acetylserotonin and melatonin in rat pineal gland

Adenosine, S-adenosyl-L-homocysteine, adenosine analogs such as 5'-N-ethylcarboxamidoadenosine and mioflazine, a nucleoside transport inhibitor, injected intraperitoneally at 09.00 h during the light period increased melatonin levels in the pineal gland of the rat. The largest increase occurred with 1 mg/kg 5'-N-ethylcarboxamidoadenosine. A representative time-response curve with 5'-N-ethylcarboxamidoadenosine (1 mg/kg) showed a maximal peak of N-acetylserotonin and melatonin 2 and 4 h after injection, respectively. These results are discussed in relation with the possible modulation through A2 receptors of melatonin synthesis in the pineal gland.

The chemical synthesis of high specific-activity [35S]adenosylhomocysteine

The study of the family of transmethylases, critical to normal cellular function and often altered in cancer, can be facilitated by the availability of a high specific-activity S-adenosylhomocysteine. We report the two-step preparation of [35S]adenosylhomocysteine from [35S]methionine at a specific activity of 1420 Ci/mmol in an overall yield of 24% by a procedure involving demethylation of the [35S]methionine to [35S]homocysteine followed by condensation with 5'-chloro-5'-deoxyadenosine. The ease of the reactions, ready availability and low cost of the reagents and high specific-activity and stability of the product make the procedure an attractive one with many uses, and superior to current methodology.

Pharmacokinetics and metabolism of S-adenosyl-L-homocysteine, in rats and dog

Tissue distribution, metabolism and excretion of 14C-S-adenosyl-L-homocyteine were investigated in rat after oral and intraperitoneal administration. The radioactivity was distributed rapidly to the tissues. The urine was the major route of excretion: respectively 32% and 52% of radioactivity were excreted in 48 h urine after oral and intraperitoneal administration. Analysis of urine by HPLC showed that the major part of the radioactivity could be identified as uric acid. Absorption and pharmacokinetic parameters were determined in dog after oral and intravenous administration. The experimental data were fitted to a biexponential equation from a two-compartment open model.

Effect of S-adenosyl-L-homocysteine upon sleep in p-chlorophenylalanine pretreated rats

S-Adenosyl-L-homocysteine (7 mg/kg), administered to PCPA-pretreated rats, was able to restore normal SWS and PS quantities, as well as circadian rhythms. This effect was at its maximum when SAH was injected 48 h after PCPA (400 mg/kg). These results are discussed in terms of post-synaptic synergetic control by SAH of serotonergic and noradrenergic nerve terminals via the periventricular system and caudal medulla in relation to environmental input.