As per the Opinion of the Scientific Committee on Food on the Tolerable Upper Intake Level of Vitamin B6 (Nov 2000), “Krinkle and Fitzgerald (1988) have shown that the type of neurotoxicity produced by pyridoxine in the rat is a function of the dose and duration of administration. Rats administered single high doses (1200 mg/kg) of pyridoxine were observed to have neuronopathy (damage to the cell body), those administered lower chronic doses (200 mg/kg for 12 weeks) were observed to have axonopathy to the distal portion of sensory nerves. These workers also reported that animals administered pyridoxine for five days a week had considerably less damage than those dosed every day”.
Articles on B6 and animal studies:
Ultrastructural Lesions of Pyridoxine Toxicity in Beagle Dogs Beagles-Damage-to-Cells (PDF)
The Behavior of Muscle Phosphorylase as a Reservoir for Vitamin B6 in the Rat
Effects of Excess Vitamin B6 Intake on Cerebral Cortex Neurons in Rat: An Ultrastructural Study
Thyroid Function in Pyridoxine-Deficient Young Rats
Hypothyroidism of Hypothalamic Origin in Pyridoxine-Deficient Rats
An Investigation of Selected Toxic Effects of Pyridoxal and Pyridoxine in the Sprague-Dawley Rat
Pyridoxine (Vitamin B6) Neurotoxicity: Enhancement by Protein-Deficient Diet
Pathologic Processes of Lumbar Primary Sensory Neurons Produced by High Doses of Pyridoxine in Rats
Pyridoxine Induced Neuropathy by Subcutaneous Administration in Dogs
High-Dosage Pyridoxine-Induced Auditory Neuropathy and Protection with Coffee in Mice
Pyridoxine-Induced Neuropathy in Rats: A Sensory Neuropathy that Responds to 4-Methylcatechol
Pyridoxine-Induced Toxicity in Rats: A Stereological Quantification of the Sensory Neuropathy