Читать книгу Canine and Feline Epilepsy - Luisa De Risio - Страница 176

The toxic mechanism of lead is caused predominantly by its ability to substitute for other polyvalent cations (particularly divalent cations, such as calcium (Ca2+) and zinc (Zn2+)) in multiple molecular processes, and subsequently affect metal transport, energy metabolism, membrane ionic channel conduction, inter- and intracellular signalling, diverse enzymatic processes (including sulfhydryl-containing enzymes involved in haem synthesis), protein maturation, cell adhesion and regulation of gene transcription. The effects of lead neurotoxicity include decreased cellular energy metabolism, impaired haem biosynthesis (resulting in increased erythrocytes fragility, basophilic stippling and circulating nucleated erythrocytes), oxidative stress, lipid peroxidation, altered activity of second messenger systems, altered neurotransmitter release (e.g. decreased GABA neurotransmission) and neurotransmitter receptor density, excitotoxicity, apoptosis impaired development and function of oligodendrocytes, abnormal myelin formation, abnormal neurotrophic factor expression, abnormal dendritic branching patterns and disruption of the blood-brain barrier (Lidsky and Scneider, 2003; Garza et al., 2006).