title: Administration of 1,25-dihydroxyvitamin D3 results in the elevation of hippocampal seizure threshold levels in rats.
abstract: Electrical stimulation of the dorsal hippocampal formation of the rat was employed to determine the effect of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), the hormonal form of vitamin D, on induced seizure thresholds. Stereotaxic injection of 100 micrograms or 50 micrograms 1,25-dihydroxyvitamin D3 in 2 microliter propylene glycol into the hippocampus resulted in a significant elevation in seizure threshold in all animals treated. 1,25-dihydroxyvitamin D3-induced increases were noted within 5-10 min and lasted at least 120-180 min after injection when the experiments were terminated. Intravenous injection of 1,25-(OH)2D3 also resulted in a significant elevation of seizure threshold; however, the increase was transient, lasting only 30 min. This effect was specific since 200 micrograms vitamin D3 or 200 micrograms 25-hydroxyvitamin D3 (25-(OH)D3), injected into the hippocampus, had no effect on seizure threshold levels. This investigation represents the first direct demonstration of a role for 1,25-(OH)2D3 in the regulation of seizure activity and suggests, along with the previously demonstrated presence of immunoreactive vitamin D-dependent calcium binding protein and receptors for 1,25-dihydroxyvitamin D3 in the brain, that the vitamin D endocrine system may play a significant role in the physiological mechanisms underlying convulsive disorders.
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000627:therapeutic use*; D004558:Electric Stimulation; D004569:Electroencephalography; D006624:Hippocampus / Q000503:physiopathology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012640:Seizures / Q000503:physiopathology / Q000517:prevention & control*
chemical_list: D002117:Calcitriol