Extracranial transport of brain lymphatics via cranial nerve in human.

Extracranial waste transport from the brain interstitial fluid to the deep cervical lymph node (dCLN) is not extensively understood. The present study aims to show the cranial nerves that have a role in the transport of brain lymphatics vessels (LVs), their localization, diameter, and number using podoplanin (PDPN) and CD31 immunohistochemistry (IHC) and Western blotting. Cranial nerve samples from 6 human cases (3 cadavers, and 3 autopsies) were evaluated for IHC and 3 autopsies for Western blotting. The IHC staining showed LVs along the optic, olfactory, oculomotor, trigeminal, facial, glossopharyngeal, accessory, and vagus nerves. However, no LVs present along the trochlear, abducens, vestibulocochlear, and hypoglossal nerves. The LVs were predominantly localized at the endoneurium of the cranial nerve that has motor components, and LVs in the cranial nerves that had sensory components were present in all 3 layers. The number of LVs accompanying the olfactory, optic, and trigeminal nerves was classified as numerous; oculomotor, glossopharyngeal, vagus, and accessory was moderate; and facial nerves was few. The largest diameter of LVs was in the epineurium and the smallest one was in the endoneurium. The majority of Western blotting results correlated with the IHC. The present findings suggest that specific cranial nerves with variable quantities provide a pathway for the transport of wastes from the brain to dCLN. Thus, the knowledge of the transport of brain lymphatics along cranial nerves may help understand the pathophysiology of various neurological diseases.

The brainstem connections of the supplementary motor area and its relations to the corticospinal tract: Experimental rat and human 3-tesla tractography study.

Although the supplementary motor area (SMA) is a large region on the medial surface of the frontal lobe of the brain, little is known about its function. The current study uses 3-tesla high-resolution diffusion tensor tractography (DTI) in healthy individuals and biotinylated dextran amine (BDA) and fluoro-gold (FG) tracer in rats to demonstrate the afferent and efferent connections of the SMA with brainstem structures. It also aims to clarify how SMA fibers relate to the corticospinal tract (CST). The BDA (n = 6) and FG (n = 8) tracers were pressure-injected into the SMA of 14 Wistar albino rats. Light and fluorescence microscopy was used to capture images of the FG and BDA-labeled cells and axons. High-resolution 3-tesla DTI data were acquired from the Human Connectome Project database. Tracts between the SMA and brainstem structures were analyzed using diffusion spectrum imaging (DSI) studio software. The FG injections into the SMA showed afferent projections from mesencephalic (periaqueductal gray matter, substantia nigra pars reticulata, ventral tegmental area, inferior colliculus, mesencephalic reticular, tegmental, and raphe nuclei), pontine (locus coeruleus, pontine reticular and vestibular nuclei), and medullary (area postrema, parabrachial, and medullary reticular nuclei) structures. The anterograde tracer BDA injections into the SMA showed efferent connections with mesencephalic (periaqueductal gray, substantia nigra pars compacta, dorsal raphe, trigeminal motor mesencephalic, and mesencephalic reticular nuclei), pontine (locus coeruleus, nucleus of the lateral lemniscus, vestibular, cochlear, and pontine reticular nuclei), and medullary (area postrema, medullary reticular, olivary, and parabrachial nuclei) structures. The SMA had efferent but no afferent connections with the cerebellar nuclei. The DTI results in healthy human subjects highly corresponded with the experimental results. Further, the DTI results showed a distinct bundle that descended to spinal levels closely related to the CST. Understanding SMA's afferent and efferent connections will enrich our knowledge of its contribution to various brainstem networks and may provide new perspectives for understanding its motor and non-motor functions.

The Effects of Optogenetic Activation of Astrocytes on Spike-and-Wave Discharges in Genetic Absence Epileptic Rats.

Background: Absence seizures (petit mal seizures) are characterized by a brief loss of consciousness without loss of postural tone. The disease is diagnosed by an electroencephalogram (EEG) showing spike-wave discharges (SWD) caused by hypersynchronous thalamocortical (TC) oscillations. There has been an explosion of research highlighting the role of astrocytes in supporting and modulating neuronal activity. Despite established in vitro evidence, astrocytes' influence on the TC network remains to be elucidated in vivo in the absence epilepsy (AE). Purpose: In this study, we investigated the role of astrocytes in the generation and modulation of SWDs. We hypothesize that disturbances in astrocytes' function may affect the pathomechanism of AE. Methods: To direct the expression of channelrhodopsin-2 (ChR2) rAAV8-GFAP-ChR2(H134R)-EYFP or to control the effect of surgical intervention, AAV-CaMKIIa-EYFP was injected into the ventrobasal nucleus (VB) of the thalamus of 18 animals. After four weeks following the injection, rats were stimulated using blue light (~473 nm) and, simultaneously, the electrophysiological activity of the frontal cortical neurons was recorded for three consecutive days. The animals were then perfused, and the brain tissue was analyzed by confocal microscopy. Results: A significant increase in the duration of SWD without affecting the number of SWD in genetic absence epileptic rats from Strasbourg (GAERS) compared to control injections was observed. The duration of the SWD was increased from 12.50 ± 4.41 s to 17.44 ± 6.07 following optogenetic stimulation in GAERS. The excitation of the astrocytes in Wistar Albino Glaxo Rijswijk (WAG-Rij) did not change the duration of SWD; however, stimulation resulted in a significant increase in the number of SWD from 18.52 ± 11.46 bursts/30 min to 30.17 ± 18.43 bursts/30 min. Whereas in control injection, the duration and the number of SWDs were similar at pre- and poststimulus. Both the background and poststimulus average firing rates of the SWD in WAG-Rij were significantly higher than the firing recorded in GAERS. Conclusion: These findings suggest that VB astrocytes play a role in modulating the SWD generation in both rat models with distinct mechanisms and can present an essential target for the possible therapeutic approach for AE.

Connections of the Dentate Nucleus with the Amygdala: Experimental Rat and Human 3-Tesla Tractography Study.

Background: The role of the cerebellum in motor function is well recognized. However, its role in higher nervous system activities such as cognition, emotion, endocrine, and autonomic activities is less known. The present study aims to show direct dento-amygdala projections using a biotinylated dextran amine (BDA) tracer in rats and 3-tesla (T) high-resolution diffusion tensor imaging (DTI)-based tractography in humans. Materials and Methods: The BDA tracer was pressure injected into the dentate nucleus of the cerebellum of Wistar albino rats. Labeled cells and axons were documented. High-resolution 3-T tractography data were obtained from the Human Connectome Project database. Dento-amygdala tracts were analyzed using diffusion spectrum imaging (DSI) Studio software. Results: The experimental study showed bilateral projections between the dentate nucleus and the central and basal nuclei and ipsilateral projections between lateral nuclei of the amygdala. The fibers from the dentate nucleus reached the amygdala through the superior cerebellar peduncle (SCP), and the contralateral fibers crossed in the decussation of SCP at the midbrain. The dento-amygdala results of the experimental study corresponded with the 3-T tractography findings on humans. Additionally, DTI findings showed that most of the dentate fibers passed through the hypothalamus before reaching the amygdala, and the amygdalae of the two sides are connected through the anterior commissure. Discussion: The 3-T DTI data of adult humans showed both direct dento-amygdala and indirect dento-hypothalamo-amygdala projections. Thus, this may indicate cerebellar contribution in modulation of emotional and autonomic functions. Furthermore, this can explain the emotional and cognitive deficits that occur in patients with cerebellar or SCP damage. Impact statement The present study showed direct dento-amygdala connections in the rat brain and human brain, which may provide evidence for cerebellar contribution in modulation of emotional and autonomic functions.

Does astrocyte gap junction protein expression differ during development in absence epileptic rats?

Intercellular communication via gap junctions (GJs) has a wide variety of complex and essential functions in the CNS. In the present developmental study, we aimed to quantify the number of astrocytic GJs protein connexin 30 (Cx30) of genetic model of absence epilepsy rats from Strasbourg (GAERS) at postnatal P10, P30, and P60 days in the epileptic focal areas involved in the cortico-thalamic circuit. We compared the results with Wistar rats using immunohistochemistry and western blotting. The number of Cx30 immunopositive astrocytes per unit area were quantified for the somatosensory cortex (SSCx), ventrobasal (VB), and lateral geniculate (LGN) thalamic nuclei of the two strains and Cx30 western blot was applied to the tissue samples from the same regions. Both immunohistochemical and western blot results revealed the presence of Cx30 in all regions studied at P10 in both Wistar and GAERS animals. The SSCx, VB, and LGN of Wistar animals showed progressive increase in the number of Cx30 immunopositive labeled astrocytes from P10 to P30 and reached a peak at P30; then a significant decline was observed from P30 to P60 for the SSCx and VB. However, in GAERS Cx30 immunopositive labeled astrocytes showed a progressive increase from P10 to P60 for all brain regions studied. The immunohistochemical data highly corresponded with western blotting results. We conclude that the developmental disproportional expression of Cx30 in the epileptic focal areas in GAERS may be related to the onset of absence seizures or may be related to the neurogenesis of absence epilepsy.

Comparison of astrocytes and gap junction proteins in the white matter of genetic absence epileptic and control rats: an experimental study.

OBJECTIVES: The role of white matter astrocytes in absence epilepsy is unknown. The present study aims to quantify astrocytic markers glial fibrillary acidic protein (GFAP), gap junction's proteins connexin 30 (Cx30) and connexin 43 (Cx43) in the corpus callosum (CC) of genetic absence epileptic rats from Strasbourg (GAERS), Wistar albino glaxo rats from Rijswijk (WAG/Rij)and compare the results with control animals. METHODS: -The density of GFAP, Cx30 and Cx43 positive astrocytes in per unite area were quantified in the CC of GAERS, WAG/Rij and control animals using immunohistochemistry and real-time quantitative polymerase chain reaction (RT-qPCR). The quantifications were made from three regions of CC; below the primary somatosensory (S1BF), below the motor (M1) and below the retrosplenial (RSG) cortices. RESULTS: oThe number GFAP, Cx30 and Cx43 immunopositive astrocytes showed heterogeneous distribution within the CC. The GFAP immunopositive astrocytes was significantly high in the S1BF region of the three strains. The immunopositive GFAP and Cx43 showed significant decrease in the S1BF and M1 regions in GAERS and WAG/Rij compared to control animals, however, an increase in the immunopositive Cx30 was observed in the same regions in both GAERS and WAG/Rij compared to control Wistar animals but the increase was significant for GAERS but not for WAG/Rij. The RT-qPCR analysis was corroborated by GFAP immunohistochemistry results. CONCLUSION: The different expression pattern of the two Cx's in the CC of the epileptic strains compared to control animals may indicate a compensatory response or maybe the cause of generalization of absence seizures.

Comparison of the Morphologic and Mechanical Features of Human Cranial Dura and Other Graft Materials Used for Duraplasty.

OBJECTIVE: This study aimed to compare the thickness and mechanical properties of the frontal; parietal; temporal; occipital human dura; autogenous grafts (facia lata, temporal fascia, galea aponeurotica); and artificial dura. METHODS: Sagittal and transverse dura samples were obtained from standard regions of the cranial dura from 30 autopsies for histologic and mechanical property measurements. Identical measurements were made for the autogenous grafts artificial dura, and the results were statistically analyzed. RESULTS: The thickness of the temporal (0.35 ± 0.11 mm), parietal (0.44 ± 0.13 mm), frontal (0.38 ± 0.12 mm), and occipital (0.46 ± 0.18 mm) dura showed regional variations. The parietal and occipital dura were significantly thicker than the temporal dura. The occipital dura was considerably thicker than the frontal dura. The frontal and temporal dura of males were significantly thicker than females. The sagittal maximum tensile force measurements were significantly greater than transverse, for the frontal, temporal, and occipital dura. The stiffness measurements in sagittal direction were greater than the measurements in transverse direction for the frontal dura. The mechanical properties and thickness of the autogenous and artificial dura were not similar to the human dura. CONCLUSIONS: The thickness and mechanical properties of the regional cranial dura should be taken into consideration for a better cure and fewer complications. The mechanical properties of sagittal and transverse dura should be kept in mind for the preference of dura material. The present study's data can pave the way to produce artificial regional dura by mimicking the thickness and mechanical properties of the human dura.

Non-motor connections of the pedunculopontine nucleus of the rat and human brain.

INTRODUCTION: The connections of the pedunculopontine nucleus (PPN) with motor areas of the central nervous system (CNS) are well described in the literature, in contrast relations with non-motor areas are lacking. Thus, the aim of the present study is to define the non-motor connections of the PPN in rats using the fluoro-gold (FG) tracer and compare the presence of these connections in healthy human adults using diffusion tensor tractography (DTI). MATERIALS AND METHODS: We injected FG into the PPN of 12 rats. The non-motor connections of the PPN with cortical, subcortical, and brainstem structures were documented. The non-motor connections of the rats were compared with the DTI obtained from 35 healthy adults. RESULTS: The results of the tract-tracing study in the rat showed that the PPN was connected to non-motor cortical (cingulate, somatosensory, visual, auditory, medial frontal cortices), subcortical (amygdala, hypothalamus, thalamus, habenular, and bed nucleus of stria terminalis), and brainstem (medullary reticular, trigeminal spinal, external cuneate, pontine reticular, vestibular, superior and inferior colliculus, locus ceruleus, periaqueductal gray, parabrachial, dorsal raphe, pretectal, lateral lemniscus nuclei, and the contralateral PPN) structures. The DTI obtained from healthy adults showed similar PPN non-motor connections as in rats. CONCLUSION: Understanding the connections of the PPN with non-motor cortical, subcortical, and brainstem areas of the CNS will enrich our knowledge of its contribution in various circuits and the areas that PPN activity can influence. Further, it will provide insight into the role of Parkinson's disease and related disorders and explain the non-motor complications which occur subsequent to deep brain stimulation (DBS) of the PPN.

Comparing astrocytic gap junction of genetic absence epileptic rats with control rats: an experimental study.

The synchronization of astrocytes via gap junctions (GJ) is a crucial mechanism in epileptic conditions, contributing to the synchronization of the neuronal networks. Little is known about the endogenous response of GJ in genetic absence epileptic animal models. We evaluated and quantified astrocyte GJ protein connexin (Cx) 30 and 43 in the somatosensory cortex (SSCx), ventrobasal (VB), centromedian (CM), lateral geniculate (LGN) and thalamic reticular (TRN) nuclei of thalamus of genetic absence epilepsy rats from Strasbourg (GAERS), Wistar albino glaxo rats from Rijswijk (WAG/Rij) and control Wistar animals using immunohistochemistry and Western Blot. The Cx30 and Cx43 immunopositive astrocytes per unit area were quantified for each region of the three animal strains. Furthermore, Cx30 and Cx43 Western Blot was applied to the tissue samples from the same regions of the three strain. The number of Cx30 immunopositive astrocytes showed significant increase in both GAERS and WAG/Rij compared to control Wistar in all brain regions studied except LGN of WAG/Rij animals. Furthermore, Cx43 in both GAERS and WAG/Rij showed significant increase in SSCx, VB and TRN. The protein expression was increased in both Cx30 and Cx43 in the two epileptic strains compared to control Wistar animals. The significant increase in the astrocytic GJ proteins Cx30 and Cx43 and the differences in the co-expression of Cx30 and Cx43 in the genetically absence epileptic strains compared to control Wistar animals may suggest that astrocytic Cx's may be involved in the mechanism of absence epilepsy. Increased number of astrocytic Cx's in GAERS and WAG/Rij may represent a compensatory response of the thalamocortical circuitry to the absence seizures or may be related to the production and/or development of absence seizures.

The Complex Structure of the Anterior White Commissure of the Human Brain: Fiber Dissection and Tractography Study.

OBJECTIVE: Commissural fibers are necessary for bilateral integration, body coordination, and complex cognitive information flow between the hemispheres. The anterior commissure (AC) has a complex architecture interconnecting areas of the frontal, temporal and occipital lobes. The present study aims to demonstrate the connections and the course of the anterior (ACa) and posterior (ACp) limb of the AC using fiber dissection and diffusion tensor imaging (DTI) of the human brain. METHODS: Fiber dissection was performed in a stepwise manner from lateral to medial on 6 left hemispheres. The gray matter was decorticated and the ACa-ACp was exposed. The ACa and ACp tracts were demonstrated using a high-spatial-resolution DTI with a 3T magnetic resonance unit in 13 cases. RESULTS: Using both techniques showed that the AC has complex interconnections with large areas of the frontal (olfactory tubercles, anterior olfactory nucleus, olfactory bulb, and the orbital gyri), temporal (amygdaloidal nuclei, temporal and perirhinal cortex), and occipital (visual cortex) lobes. The ACp makes up the major component of the AC and is composed of temporal and occipital fibers. We observed that these fibers do not make a distinct bundle; the temporal fibers joined the uncinate fasciculus and the occipital fibers joined the sagittal striatum to reach their targets. CONCLUSIONS: Being aware of the course of the AC is important during transcallosal and interforniceal approaches to the third ventricle tumors and temporal lobe epilepsy surgery. The intermingling fibers of the AC can provide a better understanding of the unexplained deficit that may occur during regional surgery.

Anatomic variations of the human falx cerebelli and its association with occipital venous sinuses.

PURPOSE: Human falx cerebelli is an important anatomical structure in regard to its relations with venous structures during infratentorial approach to reach cerebellar tumors, vascular malformations, traumatic hemorrhage and Chiari malformations. The present study aim to describe the different types of variations of the falx cerebelli, its morphological features and its association with occipital venous sinuses. METHOD: In this study 49 dura mater was obtained from the Institution of Forensic Medicine. The length, width and the depth of the falx cerebelli were measured using a digital compass. The data obtained were statistically analyzed in relation to age and gender. The relations of the falx cerebelli with the occipital sinus was documented. Histological sections from the falx cerebelli were stained with Hematoxylin Eosin to evaluate the fine structure. RESULTS: Among the 49 falx cerebelli examined 36 (73.5%) were classified as normal. The average length, width and depth of the normal falx cerebelli was 3.7, 1.0 and 0.4 cm respectively. Of the 49 falx cerebelli in 1 (2%) case it was absent, in 5 cases (10.2%) duplicate, in 5 cases (10.2%) triplicate, in 1 (2%) case quadruplets and in 1 case (2%) it was five-folded. The proximal and the distal attachments of the falx cerebelli showed 3 types of variations; both attachments triangular, the proximal attachments triangular and the distal ramified and distal attachments triangular and the proximal attachments ramified. The drainage of the occipital sinus of falx cerebelli with variations were evaluated. The increased number of falx cerebelli highly corresponded with the increased number of occipital sinus. CONCLUSIONS: The dural-venous variation in the posterior cranial fossa can be problematic in various diagnostic and operative procedures of this region. Neurosurgeons should be aware of such variations, as these could be potential sources of haemorrhage during the midline suboccipital and infratentorial approaches.

Morphometric Study of the Cervical Spinal Canal Content and the Vertebral Artery.

BACKGROUND: The morphological features of the cervical spinal nerves (C1-C8), their dimensions, and their anatomical relations with the vertebral artery are important for safe spinal surgery. The aim of the present study is to give detailed morphological data of the region to avoid complications. METHODS: Five formalin-fixed adult cadavers were studied. The cervical spinal nerves and the vertebral artery were exposed via the posterior approach, and detailed anatomy and morphometric measurements were evaluated. The following measurements were documented: angles between the spinal nerve and the spinal cord of C1 to C8, width of the C1 to C8 spinal nerves at their origin, distance of the spinal cord to the vertebral artery, number of dorsal rootlets, length of the dorsal root entry zone of C1 to C8, and distance between respective spinal nerves. Further, the average length and width of the transverse foramen were measured. RESULTS: The average angle between the spinal cord and the spinal nerve within the vertebral canal ranged between 54 and 87 degrees and were most acute at C5 (54 degrees) compared to the rest of the cervical spinal nerves. The average width of the spinal nerves (mean ± SD), was thickest at C5 (5.7 ± 1.2 mm) and C6 (5.8 ± 0.7 mm). The average largest distance between the vertebral artery and the spinal cord was at C2 (14.3 ± 1.7 mm) and the smallest at C5 (7.3 ± 0.9 mm) and C6 (7.3 ± 2.2 mm) spinal levels. The number of dorsal rootlets was most numerous at C6 (8.25 ± 0.6) and C7 (7.25 ± 0.9). The dorsal root entry zone length was the largest at C5 (13.0 ± 1.6 mm) and C6 (13.75 ± 0.5 mm). The distance between respective spinal nerves was largest between C2 and C3 (11.8 ± 2.2) and C7 and C8 (11.5 ± 0.6). CONCLUSION: The knowledge of detailed anatomy of the cervical spine (C1-C8) and its relations with the vertebral artery will reduce the unwanted damage to the vital structures of the region.

Fiber dissection and 3-tesla diffusion tensor tractography of the superior cerebellar peduncle in the human brain: emphasize on the cerebello-hypthalamic fibers.

Experimental studies in various species using tract-tracing techniques showed clear evidence of the presence of cerebello-hypothalamic projections. However, these connections were not clearly described in humans. In the present study we aimed to describe the direct cerebello-hypothalamic connections within the superior cerebellar peduncle (SCP) using fiber dissection techniques on cadaveric brains and diffusion tensor tractography (DTI) in healthy adults. Fiber dissection was performed in a stepwise manner from lateral to medial on 6 cerebral hemispheres. The gray matter was decorticate and fiber tracts were revealed. The SCP was exposed and the fibers were traced distally using wooden spatulas. The MRI examinations were performed in seven cases using 3-tesla 3T unit. The direct cerebello-hyothalamic pathways were exposed using high-spatial-resolution DTI. The present study using both fiber dissection and DTI in adult human showed direct cerebello-hypothalamic fibers within the SCP. The SCP fibers course anterolateral to the cerebral aqueduct reaching the level of the red nucleus of the midbrain. The majority of the fibers crosses over and reached the contralateral diencephalic structures and some of these fibers terminated at the contralateral anterior hypothalamic area. Some of the uncrossed SCP fibers reached the ipsilateral diencephalic structures and terminated at the ipsilateral posterior hypothalamic area. We further reported the close relationship of the SCP with the MCP, lateral lemniscus, red nucleus and substantia nigra. In the DTI evaluations of the SCP we exposed unilateral left cerebello-hypothalamic fibers in five cases and bilateral cerebello-hypothalamic fibers in two cases. The present study demonstrates the direct cerebello-hypothalamic connections within the SCP for the first time using fiber dissection and DTI technique in the human brain. The detailed knowledge of the cerebello-hypothalamic fibers can outline the unexplained deficit that may occur during regional surgery.

Do the Dento-Thalamic Connections of Genetic Absence Epilepsy Rats from Strasbourg Differ from Those of Control Wistar Rats?

The thalamo-cortical circuit is important in the genesis of absence epilepsy. This circuit can be influenced by connecting pathways from various parts of central nervous system. The aim of the present study is to define the dento-thalamic connections in Wistar animals and compare the results with genetic absence epilepsy rats from Strasbourg (GAERS) using the biotinylated dextran amine (BDA) tracer. We injected BDA into the dentate nucleus of 13 (n = 6 Wistar and n = 7 GAERS) animals. The dento-thalamic connections in the Wistar animals were denser and were connected to a wider range of thalamic nuclei compared with GAERS. The dentate nucleus was bilaterally connected to the central (central medial [CM], paracentral [PC]), ventral (ventral medial [VM], ventral lateral [VL], and ventral posterior lateral [VPL]), and posterior (Po) thalamic nuclei in Wistar animals. The majority of these connections were dense contralaterally and scarce ipsilaterally. Contralateral connections were present with the parafascicular (PF), ventral posterior medial, ventral anterior (VA), and central lateral (CL) thalamic nuclei in Wistar animals. Whereas in GAERS, bilateral connections were observed with the VL and CM. Contralateral connections were present with the PC, VM, VA, and PF thalamic nuclei in GAERS. The CL, VPL, and Po thalamic nucleus connections were not observed in GAERS. The present study showed weak/deficit dento-thalamic connections in GAERS compared with control Wistar animals. The scarce information flow from the dentate nucleus to thalamus in GAERS may have a deficient modulatory role on the thalamus and thus may affect modulation of the thalamo-cortical circuit.

Relationships between astrocytes and absence epilepsy in rat: An experimental study.

Astrocytes take part in the modulation of neuronal activity through the uptake and release of both GABA and glutamate. In the present study we aimed to quantify the number of astrocytes expressing the astrocyte marker glial fibrillary acidic protein (GFAP) in the somatosensory cortex (SSCx), ventrobasal (VB), centromedial (CM), reticular (TRN) and dorsal lateral geniculate (dLGN) nuclei of thalamus in Genetic Absence Epilepsy Rats from Strasbourg (GAERS), Wistar Albino Glaxo Rats from Rijswijk (WAG/Rij) and control Wistar animals. Further, we aimed to compare the GFAP protein expression levels between the three animal strains. The GFAP-immunohistochemistry was applied to sections from the SSCx, VB, CM, TRN and dLGN and GFAP-positive astrocytes were quantified for the three animal strains. Further, GFAP Western Blot was applied to the tissue samples from the same regions of the three strain. The data obtained from Wistar animals were compared with GAERS and WAG/Rij animals. The number of GFAP-positive astrocytes per unit area in all brain regions studied showed high significance between Wistar-GAERS and Wistar-WAG/Rij except the dLGN. The GAERS had significant higher endogenous GFAP expression in all brain regions studied compared to Wistar and WAG/Rij animals. These findings demonstrate a discrete difference in both GFAP-positive astrocyte populations and GFAP protein expression levels between Wistar and genetically epileptic strains (GAERS and WAG/Rij). Absence seizures are thought to result from a possible imbalance in glutamatergic and GABAergic neurotransmission. Astrocytes regulate the concentration of glutamate and GABA in the extracellular space in the brain, the difference in the astrocyte population and GFAP protein expression in the epileptic strains clearly shows the involvement of astrocytes in the mechanism of absence epilepsy.

The effect of prenatal and postnatal caffeine exposure on pentylentetrazole induced seizures in the non-epileptic and epileptic offsprings.

Caffeine, a central nervous system stimulant, has been reported to modulate seizure activity in various studies. In this study the effects of caffeine exposure on the pentylenetetrazole (PTZ) induced seizure thresholds and seizure stages in the Wistar and genetic absence epilepsy model offsprings were examined. Adult female and male Wistar rats and genetic absence epilepsy rats from Strasbourg (GAERS) consumed caffeine dissolved in water (0.3 g/L) before conception, during the gestational periods and lactation period whereas control groups of each strain received tap water. All offsprings at postnatal day 30 (PN30) subjected to 70 mg/kg of PTZ were evaluated in terms of overall seizure stages, the latency to the first generalized seizure and the c-Fos protein activity in the brain regions of somatosensorial cortex (SSCx), reticular thalamic nucleus (Rt), ventrobasal thalamus (VB), centromedial nucleus (CM) and lateral geniculate nucleus (LGN). The Wistar caffeine group had significantly shorter latency to the first generalized seizure (1.53 ±â€¯0.49 min) comparing to the Wistar control offsprings (3.40 ±â€¯0.68 min). GAERS caffeine group (6.52 ±â€¯2.48 min) showed significantly longer latency comparing to Wistar caffeine group (1.53 ±â€¯0.49 min). Although statistically not significant, GAERS caffeine group showed a longer latency comparing to the GAERS control group (4.71 ±â€¯1.82 min). In all regions of SSCx, Rt, VB, CM and LGN, GAERS caffeine group had lower c-Fos protein expression comparing to the GAERS control group (p < 0.05). Wistar caffeine rats had lower expression of c-Fos protein comparing to the Wistar control group only in SSCx. In CM, GAERS rats expressed lower c-Fos protein comparing to the Wistar control (p < 0.05). In conclusion differential effects of caffeine in the seizure modulation may involve c-Fos protein activity-dependent protection mechanisms.

Afferent projections of the subthalamic nucleus in the rat: emphasis on bilateral and interhemispheric connections.

The subthalamic nucleus (STN) is important for normal movement as well as in movement disorders. The STN is a target nuclei in patients with advanced Parkinson's disease (PD). Deep brain stimulation (DBS) is a standard surgical treatment for PD. Although DBS results in a significant reduction in motor disability, several negative side effects have been reported. Thus, to understand the side effects of DBS the connection of the STN should be well known. Therefore, the present study aims to re­examine the STN with an emphasis on poorly­ or un­documented connections. Furthermore, the bilateral and interhemispheric connections of the STN are evaluated. Fifteen male albino rats received injections of Fluoro­Gold retrograde and biotinylated dextran amine anterograde tracers into the STN. Following a 7-10 day survival period, the animals were processed according to the relevant protocol for each tracer. The present study demonstrates ipsilateral connections of the STN with cortical regions (i.e., infralimbic, cingulate, frontal, piriform, primary motor, primary sensory, insular and retrosplenial cortices), the endopiriform nucleus, basal ganglia related structures (i.e., caudate putamen, globus pallidus, ventral pallidum, nucleus accumbens, claustrum and substantia innominata) and the deep cerebellar nuclei (i.e., lateral, anterior interposed). Bilateral connections of the STN were observed with limbic (amygdala, bed nucleus of stria terminalis), hypothalamic (ventromedial, posterior, anterior, lateral and mammillary) thalamic (thalamic reticular nucleus), epithalamic (habenular nucleus), and brainstem structures (superior colliculus, substantia nigra, spinal nucleus of the trigeminal nerve, red nucleus, dorsal raphe nucleus, pedunculopontine tegmental nuclei). Interhemispheric connections between left and right STN were also observed. The present study fills important gaps in connectivity of the STN. In particular, we report STN connectivity with cortical areas (i.e., piriform, endopiriform and insular), claustrum, hypothalamic, thalamic reticular, cerebellar, habenular, trigeminal, red, cuneate and gracile nuclei and substantia innominate. These connections, which have not been previously described or poorly described, provide new routes that can alter the conceptual architecture of the basal ganglia circuitry and may modify our view of the functional identity of the STN.