Modulation of axonal sprouting along rostro-caudal axis of dorsal hippocampus and no neuronal survival in parahippocampal cortices by long-term post-lesion melatonin administration in lithium-pilocarpine model of temporal lobe epilepsy / 대한해부학회지

Feature outcome of hippocampus and extra-hippocampal cortices was evaluated in melatonin treated lithium-pilocarpine epileptic rats during early and chronic phases of temporal lobe epilepsy (TLE). After status epilepticus (SE) induction, 5 and 20 mg/kg melatonin were administered for 14 days or 60 days. All animals were killed 60 days post SE induction and the histological features of the rosrto-caudal axis of the dorsal hippocampus, piriform and entorhinal cortices were evaluated utilizing Nissl, Timm, and synapsin I immunoflorescent staining. Melatonin (20 mg/kg) effect on CA1 and CA3 neurons showed a region-specific pattern along the rostro-caudal axis of the dorsal hippocampus. The number of counted granular cells by melatonin (20 mg/kg) treatment increased along the rostro-caudal axis of the dorsal hippocampus in comparison to the untreated epileptic group. The density of Timm granules in the inner molecular layer of the dentate gyrus decreased significantly in all melatonin treated groups in comparison to the untreated epileptic animals. The increased density of synapsin I immunoreactivity in the outer molecular layer of the dentate gyrus of untreated epileptic rats showed a profound decrease following melatonin treatment. There was no neuronal protection in the piriform and entorhinal cortices whatever the melatonin treatment. Long-term melatonin administration as a co-adjuvant probably could reduce the post-lesion histological consequences of TLE in a region-specific pattern along the rostro-caudal axis of the dorsal hippocampus.

Effect of GABA[A] receptors in the rostral ventrolateral medulla on cardiovascular response to the activation of the bed nucleus of the stria terminalis in female ovariectomized rats

The areas of the bed nucleus of the stria terminalis [BST] with a high density of estrogen receptors are involved in cardiovascular regulation and send axonal projections to the rostroventrolateral medulla [RVLM]. We aimed to find the contribution of the RVLM to cardiovascular responses elicited by glutamate microinjection into the BST. Experiments were done in alpha-chloralose anesthetized ovariectomized [OVX] or OVX estrogen treated [OVX+E] female Wistar rats. Drugs were microinjected into the BST and RVLM. The average changes in mean arterial pressure [MAP] and heart rate [HR] were compared between the case and control groups using t test and with the pre-injection values using paired t test. Unilateral microinjection of glutamate [0.25 M/50 nl] into the BST decreased MAP and HR, in the OVX+E and OVX rats. These cardiovascular responses were reversibly attenuated 10 minutes after microinjection of synaptic blocker cobalt chloride [CoCl2, 5 mM/50 nl] into the ipsilateral RVLM. Re-stimulation of the BST 60 min after CoCl2 injection elicited cardiovascular responses that were not different from the control values. Ipsilateral microinjection of GABA[A] antagonist bicuculline [1.0 mM/50 nl] into the RVLM caused a 50% attenuation of glutamate induced depressor and bradycardic responses in both groups. Ipsilateral microinjection of GABA[B] antagonist, phaclophen [5.0 mM/50 nl], into the RVLM did not affect the depressor and bradycardic responses due to re-stimulation of the BST by glutamate. The RVLM sympathetic premotor neurons contain GABA[A] receptors that mediate in part the sympathoinhibitory responses to stimulation of the BST in the OVX animals