GnRH-Immunoreactive Fiber Changes with Unilateral Amygdala-Kindled Seizures
Abstract number :
1.101
Submission category :
Year :
2000
Submission ID :
2403
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Mark N Friedman, Changiz Geula, Greg Holmes, Andrew Herzog, Neuroendocrine Unit, Beth Israel Deaconess Medical Ctr, Boston, MA; Beth Israel Deaconess Medical Ctr, Boston, MA; Children's Hosp, Boston, MA.
RATIONALE: Amygdala kindling can produce reproductive dysfunction in female rats. Disruption of the gonadotropin releasing hormone (GnRH) system may be a factor (Amado D, et al., Epilepsy Research 1993;14:149-159). This investigation compared counts of hypothalamic GnRH-immunoreactive (ir) soma and fibers among unilateral kainate (KA)-injected, saline-injected and naive control female rats. Findings in the ventromedial hypothalamus are presented. METHODS: 23 adult female rats were studied and divided into 3 groups: experimental (6 left & 4 right), control (3 left & 5 right), & naive (5). Focal injection (4 ?l) of KA or saline (control) was made unilaterally into the amygdala. The animals were observed for seizures several hours postoperatively and periodically over 4 weeks. They were sacrificed 4 weeks post-injection in the diestrus phase, as were the naive animals. The brains were processed and stained for GnRH immunoreactivity using an immunoperoxidase ABC method. Total GnRH cell counts were estimated using every 5th coronal section. GnRH fiber counts were obtained using a grid intersect method in the ventrolateral part of the ventromedial nucleus (VMHVL). RESULTS: All KA animals developed seizures and amygdaloid lesions. Total GnRH cell and VMHVL fiber counts did not differ among the 3 groups. Ipsilateral (I) counts were significantly lower (p < .001) for the saline (17.4 ? 3.2) and KA groups (22.5 ? 7.5) than the naive group (46.0 16.0). Contralateral (C) counts were significantly greater (p < .01) for the KA group (53.2 ? 10.0) than the saline group (28.4 ? 7.6). C-I differences were greater for the KA group than both the saline group (30.6 ? 6.6 vs 11.0 ? 6.7; p = .05) and the naive controls (30.6 ? 6.6 vs -6.4 ? 4.8; p < .001). CONCLUSIONS: Both KA and saline injection into the amygdala are associated with an ipsilateral loss of GnRH fiber staining in the VMHVL in the female rat in diestrus at 4 weeks. Only saline counts, however, are reduced contralaterally. Contralateral KA counts are significantly higher, raising the possibility of a differential effect of KA-induced amygdaloid seizures or lesions. Supported by Winokur Family Foundation