Lateral asymmetry in activation of hypothalamic neurons with unilateral amygdaloid seizures

Purpose: Reproductive disorders are unusually frequent among women with tem poral lobe seizures. The particular type of disorder may be related to the laterality and focality of epileptiform discharges. Hen we examined whether unilateral amygdaloid seizures activate hypothalamic neurons involved in r eproductive function and reproductive endocrine secretion in female rats an d whether such activation shows lateral asymmetry. Methods: Numbers of Fos-immunoreactive (Fos-ir) neurons in various hypothal amic regions were compared for three groups of animals: (a) unilateral amyg dala-kindled, (b) implanted but unstimulated, and (c) unimplanted. Results: Fos-ir neurons showed strong ipsilateral occurrence in the medial preoptic, ventrolateral part of the ventromedial, and ventral premammillary nuclei, sexually dimorphic regions involved in reproductive endocrine regu lation. No significant lateral asymmetry was observed for other investigate d hypothalamic regions. Conclusions: Unilateral amygdaloid seizures activate hypothalamic neurons t hat regulate reproductive endocrine secretion in a laterally asymmetric fas hion. This may explain the clinical association of different reproductive e ndocrine disorders with left and right temporal epileptiform discharges.