Adolescent Morphine Exposure in Male Rats Alters the Electrophysiological Properties of Locus Coeruleus Neurons of the Male Offspring

Abstract

Opioid prescription and illegal use have been soaring, and it has become a global concern. Adolescence, as a critical developmental period, is radically influenced by drug exposure. In the recent decade, transgenerational effects of paternal environmental exposure have been given greater consideration. There is compelling evidence for the effect of paternal drug abuse such as alcohol, cocaine, and nicotine on the offspring; however, a limited number of studies have focused on the paternal effect of opioids during adolescence on progeny. Locus coeruleus (LC) is a noradrenergic nucleus involved in different brain functions and cognitive processes. The present study aimed to investigate the transgenerational effect of adolescent morphine exposure on electrophysiological properties of LC neurons of the offspring. For this purpose, adolescent male rats received morphine or saline for 10 days between postnatal days 31 and 40, and then after 20 days of washout period, they were mated with naïve female rats. Whole cell patch clamp recordings were performed in current clamp configuration from LC neurons of 14–21-day-old male offspring. The results demonstrated that the decay slope of the action potentials and the amplitude of afterhyperpolarization potential increased in morphine sired animals. Moreover, the duration of action potentials decreased in morphine sired animals. Besides, the coefficient of variation of interspike intervals increased in morphine sired animals compared to the saline sired ones. Overall, the altered electrophysiological properties observed in this study may suggest a functional enhancement of Ca2+ activated K+ channels in LC neurons of morphine sired animals.