Low - frequency stimulation of histaminergic tuberomammillary nucleus facilitates basolateral amygdaloid kindling in rats

Aim： The tuberomammillary nucleus （TM）, located in the posterior hypothalamus, is the sole seat of histaminergic neurons in the brain. In this study, we investigate whether low - frequency stimulation of TM is involved in the acquisition of amygdala kindling seizure and participated in maximal electroconvulsive shock （MES） and pentylenetetrazole （PTZ） induced convulsion models in fully amygdaloid -kindled rats. Methods： The ipsilateral or contralateral TM received lowfrequency stimulation （ 15 min train of 0. 1 ms pulses at 1 HZ and 300 -400 μA） immediately after termination of once daily kindling stimulation （2 s train of 1 ms pulses at 60 HZ and 150 -300 μA） in the right amygdala. After control animals reached fully kindled state, they were divided into two groups, one group received daily LFS plus kindling stimulation and another group only received kindling stimulation. Ten days later, all of them were tested for MES as well as PTZ induced convulsions. Results： LFS of either ipsilateral or contralateral TM significantly facilitated the progression of seizure stages and increased afterdischarge duration throughout the course of amygdaloid kindling. The marked facilitation induced by LFS on either side of the TM was predominantly due to the significant promotion of progression from stage 3 to stage 5 seizures. In addition, LFS of TM significantly increased seizure severity and prolonged forelimb and hindlimb extension durations in MES model. However, no obvious changes can be observed in PTZ convulsion model.

Low - frequency stimulation of histaminergic tuberomammillary nucleus facilitates basolateral amygdaloid kindling in rats