ABSTRACT
Nitric oxide (NO) production has been widely reported to be required for the induction of long-term potentiation (LTP) in hippocampal CA1 cells. Of the two constitutive isoforms of NO synthase, the endothelial form (eNOS) has been implicated in the induction of LTP in these cells. The distribution of eNOS within CA1 cells is not uniform, however, being present in the cell bodies and apical dendrites but absent from the basal dendrites. Using extracellular and intracellular recording techniques, we demonstrate that LTP induction in stratum radiatum synapses (onto apical dendrites) is dependent on NO production, being attenuated by pretreatment with a NOS inhibitor. LTP induced in stratum oriens synapses (onto basal dendrites) is, however, resistant to NOS inhibitors. Both forms of LTP require the activation of N-methyl-D-aspartate (NMDA) receptors because induction of LTP in both stratum radiatum and stratum oriens is blocked by AP5. Thus, it appears that synapses onto apical and basal dendrites of CA1 cells use different cellular mechanisms of LTP induction.
Subject(s)
Hippocampus/physiology , Long-Term Potentiation/physiology , Pyramidal Cells/physiology , Synapses/physiology , Animals , Cell Membrane/physiology , Electric Stimulation , Excitatory Postsynaptic Potentials/physiology , Hippocampus/cytology , In Vitro Techniques , Intracellular Membranes/physiology , Male , Rats , Rats, Sprague-DawleyABSTRACT
We examined six patients who presented with bilateral, progressive visual loss. Each patient had a bilateral decrease in visual acuity, poor color vision, and central or cecocentral scotomas. Optic nerve head appearance varied from normal to diffusely pale. All patients consumed tobacco, ethanol, or both. Each patient was folate deficient and had normal vitamin B12 levels. Patients were treated with oral folic acid, 1 mg per day. Visual acuity improved bilaterally in all patients (mean: five lines in 2 months). Folate deficiency should be considered in any patient with progressive bilateral optic neuropathy of unknown etiology. Treatment with folic acid can result in significant improvement in visual function.
Subject(s)
Folic Acid/therapeutic use , Optic Nerve Diseases/drug therapy , Administration, Oral , Adult , Alcohol Drinking/adverse effects , Amblyopia/etiology , Female , Folic Acid/administration & dosage , Folic Acid Deficiency/complications , Humans , Male , Middle Aged , Optic Nerve Diseases/etiology , Smoking/adverse effects , Visual Acuity , Visual Field Tests , Visual FieldsABSTRACT
The present study sought to determine if axonal connectivity is established between 6-month-old neostriatal transplants and the host substantia nigra. Cell suspensions of fetal neostriatum were transplanted into the adult rat neostriatum lesioned previously by kainic acid. Horseradish peroxidase injections into the ipsilateral ventral midbrain labelled the lesion site and the intact neostriatum extensively, but no appreciable anterograde or retrograde label was found within the graft. These results demonstrate a paucity of connectivity between neostriatal grafts and the host brain at a time when other investigators have described transplant-mediated recovery of function.
