Summary:Purpose: Reproductive disorders are unusually frequent among women with temporal lobe seizures. The particular type of disorder may be related to the laterality and focality of epileptiform discharges. Here we examined whether unilateral amygdaloid seizures activate hypothalamic neurons involved in reproductive function and reproductive endocrine secretion in female rats and whether such activation shows lateral asymmetry.Methods: Numbers of Fos-immunoreactive (Fos-ir) neurons in various hypothalamic regions were compared for three groups of animals: (a) unilateral amygdala-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 i n reproductive endocrine regulation. No significant lateral asymmetry was observed for other investigated hypothalamic regions.Conclusions: Unilateral amygdaloid seizures activate hypothalamic neurons that regulate reproductive endocrine secretion in a laterally asymmetric fashion. This may explain the clinical association of different reproductive endocrine disorders with left and right temporal epileptiform discharges.
Summary: Purpose: Substnatia nigra (SN) and locus coeruleus (LC) neurons are implicated in the propagation and suppression of amygdaloid seizures. Both structures are activated concomitant with amygdaloid seizure discharges. Their rnechanisms of activation, however, remain to be elucidated. SN firing is not associated with the induction of Fos imrnunoreactivity (ir), a marker of excitatory neuronal activation. LC has not been studied. The purpose of this investigation was to determine if amygdala-kindled generalized seizures could induce Fos-ir in the LC.Methods: Female Sprague-Dawley rats were killed after generalized seizures induced by amygdala electrical stimulation and stained by using Fos irnmunocytochemistry. The nurnber of Fos-ir neurons was compared between 15 animals with generalized seizures and four implanted, unstimulated controls.Results: LC-ir neurons were significantly (p < 0.05) more prevalent after seizures than in control animals. Their numbers correlated very highly with Fos-ir in the central nucleus of the amygdala (p < 0.0001). No Fos induction was observed in LC in controls or in the SN in either group.Conclusions: Amygdala-induced generalized seizures result in Fos-ir in the LC but not in the SN. This is consistent with different mechanisms of activation possibly involving disinhibition in the SN and direct excitation in the LC. Key Words: Fos-Kindling-Seizures-Locus coeruleus.The substantia nigra (SN) and locus coeruleus (LC) are brainstem structures that have been implicated in the propagation and suppression of seizures (1-3). Amygdala-kindled seizures produce short-latency, single-and multiple-unit burst firing neuronal discharges in the SN (4) and LC (5). The manner in which the SN and LC neurons are activated, however, is not known. Fos, a protein product of the immediate-early genes family, has been used extensively as a nonspecific marker of excitatory neuronal activation (6,7). Direct excitatory transmission is unlikely in the SN because amygdaloid kindling does not induceFos in SN pars reticulata (SNpr) or SN pars compacta (SNpc) neurons (6,7). Kindling-induced Fos-immunoreactivity (ir) in LC neurons has never been reported. This investigation uses Fos as a marker to determine whether amygdala-kindled seizures are associated with excitatory neuronal activation in the LC. METHODSTwenty-one female Sprague-Dawley rats (Charles River Laboratories), weighing 20CL300 g, were used in this study. Their care and use conformed to institutional policies and guidelines. The rats were maintained on a
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