Reduction of voltage-dependent calcium currents in mumps virus-infected cultures of rat hippocampal neurons

Abstract

The effects of a mumps virus infection on functional properties of embryonic hippocampal neurons in culture were analysed with special emphasis on voltage-dependent Ca²⁺ channels. Cultures with higher or lower density of glial cells (not treated or treated with mitotic inhibitor, respectively) were infected with the relatively non-cytolytic RW strain of mumps virus and currents were recorded from neurons using whole cell voltage clamp. More than 65% of neurons and glial cells contained viral antigens 1–2 days post infection (p.i.). Glial cells remained infected 6–7 days p.i., while the ratio of infected versus uninfected neurons, especially in cultures with higher glial cell density, was reduced. In both infected and uninfected cultures the somal voltage-dependent Ca²⁺ currents were stronger in cultures with a higher glial cell density, which indicates that these currents are influenced by glial cells. Introduction of the virus into cultures caused a selective decrease in inward Ca²⁺ currents, which was most marked at days 6–7 p.i., and which included both infected and unifected neurons. Spontaneous synaptic currents and other ion channel conductances appeared normal in the infected cultures. Dantrolene, which inhibits release of Ca²⁺ from intracellular stores, decreased the neurons that died during the infection. Taken together the results show that a mumps viral infection can selectively alter the number or function of somal voltage dependent Ca²⁺ channels in immature hippocampal neurons and that this may reflect a disturbed glia-nerve cell interaction.

Key Words:

• nervous system
• glial cells
• voltage clamp
• viral infection