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Nonketotic hyperglycinemia treated with strychnine, a glycine receptor antagonist
Insights
Strychnine treatment improved motor skills and behavior in an infant with nonketotic hyperglycinemia. This suggests strychnine may counteract glycine
Area of Science:
- Neuroscience
- Pediatric Neurology
- Pharmacology
Background:
- Nonketotic hyperglycinemia (NKH) is a rare metabolic disorder characterized by excessive glycine levels.
- Glycine acts as an inhibitory neurotransmitter in the central nervous system, particularly at spinal and brainstem levels.
- Current treatments for NKH are limited, highlighting the need for novel therapeutic strategies.
Observation:
- A 6.5-month-old infant diagnosed with nonketotic hyperglycinemia received oral strychnine therapy for over 12 months.
- The patient exhibited notable improvements in muscle tone, motor function, alertness (vigilance), and social interactions during treatment.
Findings:
- Strychnine, a known antagonist of glycine receptors, appeared to reverse the inhibitory effects of excessive glycine.
- Improved motor function was likely due to strychnine blocking glycine-mediated inhibition of motor neurons.
- Enhanced vigilance and social behavior may stem from strychnine's antagonism of glycine inhibition in brainstem reticular neurons.
Implications:
- Strychnine shows potential as a therapeutic agent for nonketotic hyperglycinemia, addressing both motor and cognitive/behavioral symptoms.
- This case suggests a potential role for glycine receptor antagonists in managing certain neurological disorders.
- Further research is warranted to explore the efficacy and safety of strychnine in a larger cohort of NKH patients.
Abstract:
A 6 1/2-month-old boy suffering from nonketotic hyperglycinemia has been treated for at least 12 months with oral strychnine. The drug caused improvement of muscle tone, motoricity, vigilance and social behavior. Glycine is one of the putative neurotransmitters of postsynaptic inhibition, particularly at the spinal and reticular levels, strychnine its antagonist at the postsynaptic membrane. Strychnine improved the patient's motoricity presumably by blocking the excessive glycine-mediated inhibition of motoneurons. The beneficial effect of strychnine on vigilance and social behavior is more difficult to explain but may have been related to its antagonism of glycine inhibition of brainstem reticular neurons.