Relationship Between Regional Distributions of Cytochrome C Oxidase and Copper-Delivering Chaperones in Sclerotic Hippocampi of Epilepsy Patients

Aims: A drop in copper level and the loss of energy homeostasis are both portrayed in mesial temporal lobe epilepsy (mTLE) with hippocampal sclerosis (HS) patients. Cytochrome c oxidase (COX) represents a crossroad of energy and copper metabolism; it is a key component of mitochondrial machinery and contains two copper centers. Our aim here was to examine the link between COX activity and the copper transporting system in HS. COX activity and the levels of mRNA of selected chaperones - COX11, COX17, Sco1 and Sco2 were determined in 13 anatomically distinct hippocampal regions. Methods: Study was performed on seven hippocampal samples, four of which had been acquired during the course of amygdalohippocampectomy treatment of medically intractable epilepsy and three control postmortem samples. Adjacent slices were used for Nissl staining, COX activity assay and mRNA in situ hybridization with autoradiography. Densitometry was performed using ImageJ. Results: Overall COX activity was decreased in HS compared to controls (P = 0.0003). However, 5 regions showed significantly lower COX activity in HS and 8 did not. Subiculum showed slightly higher activity in HS. The levels of mRNA levels were lowered in HS in 6 regions for COX11, 10 regions for COX17, two regions for Sco1 and 11 regions for Sco2. Conclusions: Our findings suggest the loss of energy homeostasis in HS may be related to pathological changes in specific components of copper delivery to COX, and that the impact may vary between different hippocampal regions

Temporal Processing of Vibratory Communication Signals at the Level of Ascending Interneurons in Nezara viridula (Hemiptera: Pentatomidae)

During mating, males and females of N. viridula (Heteroptera: Pentatomidae) produce sex- and species-specific calling and courtship substrate-borne vibratory signals, grouped into songs. Recognition and localization of these signals are fundamental for successful mating. The recognition is mainly based on the temporal pattern, i.e. the amplitude modulation, while the frequency spectrum of the signals usually only plays a minor role. We examined the temporal selectivity for vibratory signals in four types of ascending vibratory interneurons in N. viridula. Using intracellular recording and labelling technique, we analyzed the neurons' responses to 30 pulse duration/interval duration (PD/ID) combinations. Two response arrays were created for each neuron type, showing the intensity of the responses either as time-averaged spike counts or as peak instantaneous spike rates. The mean spike rate response arrays showed preference of the neurons for short PDs (below 600 ms) and no selectivity towards interval duration; while the peak spike rate response arrays exhibited either short PD/long ID selectivity or no selectivity at all. The long PD/short ID combinations elicited the weakest responses in all neurons tested. No response arrays showed the receiver preference for either constant period or duty cycle. The vibratory song pattern selectivity matched the PD of N. viridula male vibratory signals, thus pointing to temporal filtering for the conspecific vibratory signals already at level of the ascending interneurons. In some neurons the responses elicited by the vibratory stimuli were followed by distinct, regular oscillations of the membrane potential. The distance between the oscillation peaks matched the temporal structure of the male calling song, indicating a possible resonance based mechanism for signal recognition

The importance of copper in pathology of mesial temporal lobe epilepsy

More and more studies are identifying the regulation of metal homeostasis as one of the key points of central nervous system’s well-being. Epilepsy is a particularly interesting neurological condition when viewed in terms of the correlation between the amount of metals and the development of a seizure. This lecture will present contribution of our group to the field of metal biology in epilepsy by mapping brain metals in sclerotic hippocampus resected from drug resistant mesial temporal lobe epilepsy (mTLE) patients as surgical therapeutic approach. Direct insight into this epileptogenic area, by two powerful techniques, optical emission and mass spectrometry, has led us to investigation of copper turnover. Namely, among the examined metals, we found the deficiency of copper in sclerotic hippocampus on two levels: (i) in whole structure (ii) and locally in the areas of neuronal loss, with significant correlation between copper concentration and neuron density. Furthermore, analysis of copper metalloproteins showed: (i) significant increase or decrease in levels of protein that is participating in copper transport into the cell (CTR1) depending on the degree of hippocampal neuronal loss; (ii) and lower activity of an enzyme in which copper is part of the active site, cytochrome c oxidase, in sclerotic hippocampi of patients compared to control tissue. In our further investigations it remained to be determined whether changes in copper concentrations and copper metalloproteins are causal to pathology of mTLE or they represent epiphenomenon

A diagram explaining the terms pulse, interval and pulse period as they are used in the text.

<p>A diagram explaining the terms pulse, interval and pulse period as they are used in the text.</p

Oscillations in the membrane potential evoked by sine-wave stimuli of 105 Hz carrier frequency in CG-AC7.

<p>(A) An intracellular recording of a single response to a 100 ms stimulus. Oscillations of the membrane potential are indicated by arrows. Note that the spikes are not shown in whole; their maximum amplitude was 30 mV. (B) Waveform averages of 17 responses to the different PDs: 100 ms (<i>upper trace</i>), 700 ms (<i>middle trace</i>) and 1200 ms (<i>lower trace</i>). The periodical graded potentials (<i>arrows</i>) following the stimulus occurred in ca. 80 ms intervals. The IDs did not affect the occurrence or the size of the oscillations. Note that in the upper trace the spikes are not shown in whole, their max. amplitude reached 30 mV.</p

Response arrays from four types of vibratory interneurons.

<p>(A) to (D) Mean spike frequency response arrays (<i>uper row</i>) and peak instantaneous spike frequency response arrays (<i>lower row</i>) for CG-AC1 (N = 4, n = 3–6 for every PD/ID combination), CG-AC6 (N = 2, n = 3–6 for every PD/ID combination), CG-AC7 (N = 3; n = 3 for every PD/ID combination) and CG-AC8 (N = 2; n = 3 for every PD/ID combination). Large circles indicate a strong response, medium-sized circles indicate an intermediate response and small circles indicate a weak or no response.</p

Arborization patterns, frequency tuning and responses of vibratory interneurons CG-AC1, CG-AC6, CG-AC7 and CG-AC8.

<p><i>Left:</i> Wholemount drawings of CG-AC1 and CG-AC8 in both the CG and PTG and the CG-AC6 and CG-AC7 in the CG. <i>Middle:</i> The histograms in the middle column show the frequency preference of neurons at 20 cm/s² as the number of spikes per 20 ms stimuli of varying frequencies (N = 2–4, n = 3–24; means and SE are shown). The traces of intracellular recordings in the right column show typical responses of neurons to 105 Hz sine wave stimuli of different durations and stimulus intervals. The intensity of all stimuli was 20 cm/s². <i>Right:</i> (A) SDs were 100, 500 and 900 ms. ID was 1000 ms in all cases. (B) SDs were 100, 500 and 900 ms. ID was 1500 ms in all cases. (C) SDs were 100, 700 and 1200 ms. ID was 1500 ms in all cases. (D) SDs were 100, 700 and 1200 ms. ID was 1500 ms. Bars below the intracellular recording traces represent the stimuli.</p