3-Acetylpyridine neurotoxicity in mice

Abstract

3-acetylpyridine (3-AP) is a metabolic antagonist used in research to decrease levels of nicotinamide (niacinamide) in laboratory animals. The administration of 3-AP followed by nicotinamide to rats leads to the selective destruction of neurons in the medial inferior olive, resulting in a loss of climbing fibers innervating cerebellar Purkinje cells and a consequent ataxia manifest by alterations in both balance and gait. Although 3-AP has also been administered to mice to destroy neurons in the inferior olive, there are limited studies quantifying the consequent effects on balance, and no studies on gait. Further, the relationship between 3-AP-induced lesions of the inferior olive and behavior has not been elucidated. Because 3-AP continues to be used for experiments involving mice, this study characterized the effects of this toxin on both balance and gait, and on the neuronal integrity of several brain regions involved in motor coordination. Results indicate that C57BL/6 mice are less sensitive to the neurotoxic effects of 3-AP than rats, and a dose more than 6.5 times that used for rats produces deficits in both balance and gait comparable to those in rats. This dose led to a significant (p< 0.05) loss of NeuN(+) neurons in several subregions of the inferior olive including the rostral medial nucleus, dorsomedial cell column, ventrolateral protrusion, and cap of Kooy. Further, the number of NeuN(+) neurons in these subregions, with the exception of the dorsomedial cell column, was significantly (p<0.05) related to rotorod performance, implicating their involvement in this behavior.

Microglia permit climbing fiber elimination by promoting GABAergic inhibition in the developing cerebellum

“…The Alexa Fluor 568-conjugated dextran is thought to be relatively resistant to lysosomal activity 36 , but it might be rapidly degraded and become undetectable in our system. To test this possibility, Alexa Fluor 568-labeled CFs were partially degenerated by sequential administration of 3-acetylpyridine (3-AP), harmaline, and nicotinamide to mice 37 – 39 . As an analog of nicotinamide, 3-AP severely damages inferior olive (IO) neurons projecting CFs by metabolic disturbance.…”

Neurotoxins subvert the allosteric activation mechanism of SARM1 to induce neuronal loss

“…It was first observed three quarters of a century ago that treatment with a nicotinamide analog, 3-AP, induces rapid hindlimb paralysis and death in mice, symptoms that could be prevented by sufficient prior fortification with nicotinic acid or Nam (Woolley et al, 1943). 3-AP-treated animals develop widespread nervous system lesions, particularly in brainstem nuclei, and consecutive treatment with 3-AP and Nam was eventually developed into a useful method for specific ablation of the inferior olive in rodents (Desclin et al, 1974;Rondi-Reig et al, 1997;Wecker et al, 2017). However, the mechanism of 3-AP neurotoxicity remained unknown.…”

“…1a). Studies of anti-metabolites starting in the 1940s demonstrated that 3-acetylpyridine (3-AP), a Nam analogue, is a neurotoxin that causes degeneration in both the central and peripheral nervous systems (Beher et al, 1952;Desclin et al, 1974;Hicks, 1955;Lopiano et al, 1986;Schulz et al, 1994;Wecker et al, 2017;Woolley et al, 1943). 3-AP is structurally identical to Nam except that a methyl group replaces Nam's amino group.…”

TGF-β1 Provides Neuroprotection via Inhibition of Microglial Activation in 3-Acetylpyridine-Induced Cerebellar Ataxia Model Rats

“…3-AP, known as methyl β-pyridyl ketone, is a metabolic antagonist utilized to decrease nicotinamide level of laboratory animals in research. Although a large number of laboratory animals with neurological mutations have been reported and numerous relevant animal models mimicking the phenotype of CAs are becoming available (Manto and Marmolino, 2009), the administration of 3-AP has still been suggested as a classic method to induce the CA animal model and provokes many characteristics similar to the typical features of CA in human (Janahmadi et al, 2009;Wecker et al, 2017). The application of 3-AP selectively lesions the neurons in the medial inferior olive, leading to a loss of climbing fibers innervating cerebellar Purkinje cells and a consequent ataxia manifested by alterations in both balance and gait (Rondi-Reig et al, 1997;Gasbarri et al, 2003;Wecker et al, 2013).…”

“…Neurotoxin 3-acetylpyridine (3-AP), an antimetabolite of nicotinamide, specifically damages calbindin-expressing neurons in the inferior olive, which sends axons, termed climbing fibers, to form synapses on Purkinje cells (Wecker et al, 2017). Destruction of the nerve fibers innervating the cerebellum by 3-AP can induce CA and provoke inflammatory reactivity present in animal brain in CA (Riva-Depaty et al, 1994).…”