Long-Term Fish Oil Supplementation Attenuates Spike Wave Discharges in the Amygdala of Adult Rats with Early-Life Febrile Seizures

Abstract

Background and Objectives: Febrile seizures (FS) are neuronal disturbances frequently associated with abnormal electroencephalographic activity (EEG) as spike-wave discharges (SWDs). Fish oil (FO) has high amounts of omega-3 fatty acids (θ-3), and its effects on FS alterations are poorly understood. The aim of this work was to evaluate the effect of long-term FO supplementation on the EEG of the amygdala of adult male rats with early-life FS. Materials and Methods: Progenitor female Wistar rats, from puberty to gestation and delivery, were fed daily with a commercial diet supplemented with either fish oil (FO), palm oil (PO), or deionized water (CTRL). After parturition, male pups were exposed for 30 min to hyperthermia (HP) and then returned to their dams. After weaning, pups were fed a commercial diet and the respective treatments up to 155 days of age when electrodes were implanted in the amygdala. Results: During early life HP, the PO and CTRL groups reached maximal core temperature (CT) in comparison with the FO group. Furthermore, the FO group only has fewer myoclonus and long latency to adopt an uncontrolled posture. At an adult age, the FO group with early-life FS scored shorter periods of SWDs in amygdala EEG but without seizures and presented minor values of absolute power than the PO and CTRL groups. Conclusions: In adult rats, the long-term supplementation of FO minimizes the deleterious behavioral effects caused by early-life FS and decreases the occurrence and amplitude of SWDs in the EEG of the amygdala.

Keywords: absence epilepsy; amygdala; electroencephalogram; febrile seizures; neuroprotection; polyunsaturated fatty acids; θ-3.

Figure 1

Mean ± SE of core temperature (A), sudden arrest (B), and myoclonus (C) in pups at 5 days of age during exposure to HP. One-way ANOVA followed by a Tukey’s test. * p < 0.05 FO compared to PO and CTRL; • p < 0.05 CTRL compared to PO and FO.

Figure 2

Mean ± SE of the latency to onset of uncontrolled body posture (A), frequency of events on uncontrolled body posture (B), and permanence in uncontrolled posture during exposure to hyperthermia (C). One-way ANOVA followed by a Tukey’s test. * p < 0.05 FO compared to PO and CTRL; • p < 0.05 PO compared to CTRL and FO.

Figure 3

(A) Depiction of the sites of the electrode tips implanted in the left and right amygdala of adult rats with an early-life history of HP according to the coronal sections as per the atlas of Paxinos and Watson [42]. (B) Three examples of coronal sections of the rats’ brains show the trajectory of the electrodes. The dots show the location of the electrode tips.

Figure 4

Traces of the EEG of the rats with no early-life history of HP (NT). No abnormalities, such as SWDs, were observed during sudden arrest behaviors in either the right or left amygdala.

Figure 5

EEG traces from adult rats with an early-life history of HP in the arrest behavior condition from the right (A) and left amygdala (B). Note the occurrence of SWDs in the PO and CTRL groups: interestingly, synchronized electrical activity between the two brain hemispheres was also observed.

Figure 6

EEG segments from the right (A) and left (B) amygdala of adult rats with early-life HP correspond to the CTRL (n = 7), PO (n = 8), and FO (n = 5) groups. Mean ± SE of the period of appearance (C), onset (D), and total number of the spike-wave discharges (SWD) (E). One-way ANOVA followed by a Tukey’s test * p < 0.05 FO compared to PO and CTRL • p < 0.05 PO compared to CTRL and FO.

Figure 7

Absolute power (log, mean ± SE) of the several EEG frequencies before SWDs in the adult rats with early-life HP in the right (A) and left (B) amygdala of the CTRL, palm oil (PO), and fish oil (FO) groups. One-way ANOVA followed by a Tukey’s test. * p < 0.05 FO compared to CTRL and PO at each Hz analyzed.

Figure 8

Absolute power (log, mean ± SE) of several EEG frequencies during SWD events in the adult rats with early-life HP in the right (A) and left (B) amygdala of the CTRL, PO, and FO groups. One-way ANOVA followed by a Tukey’s test. * p < 0.05 FO compared to CTRL and PO at each Hz analyzed.

Figure 9

Absolute power (log, mean ± SE) of the EEG frequencies after the occurrence of SWDs in the adult animals with an early-life history of HP in the right (A) and left (B) amygdala of the CTRL, palm oil (PO), and fish oil (FO) groups. One-way ANOVA followed by a Tukey’s test. * p < 0.05 FO compared to CTRL and PO at each Hz analyzed.