Long-lasting effects of feline amygdala kindling on monoamines, seizures and sleep

This report describes the relationship between monoamines, sleep and seizur es before and 1-month after amygdala kindling in young cats (<1 year old; n =8; six female and two male). Concentrations (fmoles of norepinephrine or N E, dopamine or DA and serotonin or 5-HT) were quantified in consecutive, 5- min microdialysis samples (2 <mu>l/min infusion rate) from amygdala and loc us ceruleus complex (LC) during four, 6-8-h polygraphic recordings before ( n=2) and 1 month post-kindling (n=2); 5-min recording epochs were temporall y adjusted to correspond to dialysate samples and differentiated according to dominant sleep or waking state (lasting greater than or equal to 80% of 5-min epoch) and degree of spontaneous seizure activity (number and duratio n of focal versus generalized spikes and spike trains and behavioral seizur e correlates). Post-kindling records in each cat were divided into two grou ps (n=1 record each) based on higher or lower spontaneous EEG and behaviora l seizure activity and compared to pre-kindling records. We found: (1) befo re and after kindling, NE and 5-HT but not DA concentrations were significa ntly lower in sleep than waking at both sites; (2) after kindling, each cat showed cyclic patterns, as follows: (a) higher NE, 5-HT and DA concentrati ons accompanied increased seizure activity with delayed sleep onset latency and increased sleep fragmentation (reduced sleep state percentages, number of epochs and/or epoch duration) in one recording versus (b) lower monoami nergic concentrations accompanied reduced seizure activity, rapid sleep ons et and reduced sleep disruption in the other recording. The alternating, po st-kindling pattern suggested 'rebound' effects which could explain some co ntroversies in the literature about chronic effects of kindling on monoamin es and sleep-waking state patterns. (C) 2001 Elsevier Science B.V. All righ ts reserved.