Prelimbic Cortex Deep Brain Stimulation Reduces Binge Size in a Chronic Binge Eating Rat Model.

BACKGROUND: Binge eating (BE) involves the consumption of a large amount of food in a short period of time and a loss of control during the binge episode. It is a key feature of the major subtypes of eating disorders like bulimia nervosa, BE disorder, anorexia nervosa binge/purge type. Alterations in the mesocorticolimbic pathway play a crucial role in its pathophysiology. OBJECTIVES: We hypothesized that BE rats receiving deep brain stimulation (DBS) in the prelimbic cortex, a functional analog of the dorsolateral prefrontal cortex in humans, would have a reduced binge size compared with those receiving sham stimulation. METHODS: Eight male Sprague-Dawley rats were implanted with a DBS electrode in the left prelimbic cortex. A protocol which included limited access to a "sweet-fat" diet was used to achieve a chronic BE state in the rats. After reaching a stable binge size, each rat had undergone sham, low-frequency stimulation (60 Hz), and high-frequency (130 Hz) stimulation for 3 sessions each, and 2 consecutive treatments were separated by at least 2 empty sessions to allow a washout of the effects. A one-way ANOVA was used for the data analysis. RESULTS: Low-frequency (60 Hz) stimulation of the prelimbic cortex significantly reduced the binge size compared to the sham stimulation (p < 0.0001). High-frequency DBS (130 Hz) had no significant influence on this behavior when compared to sham stimulation (p = 0.9). CONCLUSIONS: This study suggests that low-frequency prelimbic cortex stimulation in BE would be useful for correcting prefrontal hypofunction which is strongly associated with BE and addiction pathogenesis.

Diagnostic utilities of tracheal ultrasound and USB-endoscope for the confirmation of endotracheal tube placement: A cadaver study.

OBJECTIVES: Confirmation of the endotracheal tube placement (CoETP) has the utmost importance in the management of an airway. Visualization of tracheal rings or carina with a fiber-optical bronchoscope (FOB) has considered to be a reliable method for the CoETP. However, FOB is expensive, time-consuming, and not always practical. Inexpensive endoscopic USB-cameras were shown to aid intubation successfully and reliably. On the other hand, there have been no studies investigating their use for the CoETP. Tracheal ultrasonography (TUS) is also a new, inexpensive and widely available alternative. A cadaver study has planned to evaluate the diagnostic utility of TUS and a USB-camera. METHODS: This study was conducted in the Anatomy Lab of a University on a fresh frozen female cadaver. Three senior Emergency Physicians have intubated the cadaver, and performed TUS or USB-endoscopy. We have prepared a randomized intubation list (n=96) in three blocks (3 times 32) as to include equal number of esophageal and tracheal intubations (48 for each). Each EP is performed all three interventions (intubation, TUS and USB-endoscopy) in consecutive blocks of 32 intubations, in turn. The position of the tube has been verified from a 2cm wide ostium on the proximal trachea. RESULTS: In this study, all intubations (n=96, 100%) were correctly identified as tracheal or esophageal with both TUS and USB-camera. Both the sensitivity and specificity of TUS and USB-endoscopy for the CoETP were 100.0%. CONCLUSION: The perfect accuracy of TUS and USB-endoscopy, have placed those techniques in a unique position as an alternative in resource-poor situations.

Effect of hyperbaric oxygen therapy on cerebral vasospasm: a vascular morphometric study in an experimental subarachnoid hemorrhage model.

This study was undertaken to investigate the preventive or therapeutic effect of hyperbaric oxygen therapy (HBOT) on cerebral vasospasm following experimental subarachnoid hemorrhage (SAH). Twenty rabbits were assigned randomly to one of four groups. Animals in Group I were not subjected to SAH or sham operation (control group, n = 5). Animals in Group II were subjected to sham operation and received no treatment after the procedure (sham group, n = 5). Animals in Group III were subjected to SAH and received no treatment after SAH induction (SAH group, n = 5). Animals in Group IV were subjected to SAH and received five sessions of HBOT at 2.4 atmospheres absolute (ATA) for 2 h (treatment group, n = 5). Animals were euthanized by perfusion and fixation 72 h after procedures. Basilar artery vasospasm indices, arterial wall thicknesses, and cross-sectional luminal areas were evaluated. Statistical comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests. Mean basilar artery vasospasm index in the treatment group was significantly smaller than in the SAH group. Mean basilar artery wall thickness in the treatment group was significantly smaller than in the SAH group. Mean basilar artery cross-sectional luminal area in the treatment group showed an increase relative to the SAH group, but this difference remained statistically insignificant. Our results demonstrated that repeated application of HBOT at 2.4 ATA for 2 h attenuated vasospastic changes such as increased vasospasm index and arterial wall thickness. HBOT is thus a promising candidate for SAH-induced vasospasm. Further studies are needed to evaluate maximal effect and optimal application regimen.

The effect of growth hormone on motor findings and dendrite morphology in an experimental Parkinson's disease model.

Approaches for the induction of neurogenesis and neuronal recovery through several modalities are gaining popularity in Parkinson's disease (PD). Growth hormone (GH) seems to have a role in the reversal of neural function following brain injury as well as in normal brain development and function; therefore, the use of GH may represent a feasible strategy in the management of PD. This experimental study aimed to evaluate the effect of growth hormone on motor function and dendrite morphology in rats with 6-hydroxydopamine (6-OHDA)-induced PD model. Thirty-six Sprague Dawley rats were included and randomly allocated into one of the six study groups: two controls and four treatment groups that received daily subcutaneous growth hormone injections for 21 days, 1, 2, and 3 months. PD model was induced through unilateral 6-OHDA injection to the nigrostriatal pathway. The following assessments were made: apomorphine rotation test, stepping test, and tissue examinations for tyrosine hydroxylase and dendrite morphology. The apomorphine rotation test and the stepping test confirmed the presence of PD. These tests as well as dendritic spine density/number and length assessments showed improvement in PD findings over time with GH administration. Findings of this study suggest that GH administration may improve dendrite morphology and motor function in the PD model, which may translate into symptom relief and quality of life improvement in patients with PD. Such potential benefits should be tested in robust clinical studies.

The effects of regular swimming exercise and melatonin on the neurons localized in the striatum of hemiparkinsonian rats.

Parkinson's disease is a progressive neurodegenerative movement disorder. We aimed to investigate the effects of regular swimming exercise and melatonin applied in the 6-Hydroxydopamine-induced Parkinson's disease rats by analysing dendritic spine of striatal neurons. Twenty-four male Wistar albino rats were used. 6-Hydroxydopamine unilaterally injected four (control, exercise, melatonin and exercise + melatonin) groups were included in the study. Tyrosine hydroxylase expression was detected by immunohistochemistry. Neurons and structures were identified from three-dimensional images by Neurolucida software. There was not any apparent difference for tyrosine hydroxylase positive neurons in the substantia nigra pars compacta and fibres in the striatum between the lesion sides of hemiparkinsonian groups. The treatment groups blocked the apomorphine-induced increase in rotations compared to the control group. In stepping test, the treatment groups prevented the loss of stepping in the contralateral side of hemiparkinsonian groups. The melatonin mostly had a positive effect on motor activity tests. In morphological analyses, the 6-Hydroxydopamine-induced lesion led to the reduction of the total dendritic length and number of branches. In the treatment groups, the reduction of the dendritic parameters was not observed. 6-Hydroxydopamine lesion led to a decrease in the total spine density, spine densities of thin and mushroom types. The exercise and melatonin treatments prevented the loss of spine density. The exercise treatment prevented the loss of spine density of mushroom type spines. The melatonin treatment blocked the loss of spine density of stubby type. In conclusion, these results provide evidence for effective additional protective therapeutic strategies for Parkinson's disease. In conclusion, results from the current study provide evidence for swimming exercise and melatonin as a promising candidate for effective additional protective strategies for PD.

Differences in Neurodegeneration Between Kainic Acid-Injected GAERS and Wistar Rats.

AIM: To compare neurodegenerative changes using the Fluoro-Jade B staining, following status epilepticus induced by intraamygdaloid injection of kainic acid in Genetic Absence Epilepsy Rats from Strasbourg (GAERS) and non-epileptic control Wistar rats. MATERIAL AND METHODS: A single unilateral intra-amygdaloid kainic acid (750 ng) was administered in adult male GAERS and Wistar rats to induce status epilepticus. We recorded electroencephalogram (EEG) and behavioral changes throughout the experiments. After 1 week of the kainic acid injection, rats were sacrificed, and the brains were removed. We obtained 20λm sections and processed them for Fluoro-Jade B and Nissl staining, which were evaluated semi-quantitatively. RESULTS: Following kainic acid injections, status epilepticus developed in all rats. In GAERS rats, motor seizures were considerably delayed, with no statistically significant difference in the number of seizures. However, statistically significant differences were observed in the Fluoro-Jade B staining in GAERS rats between contralateral and ipsilateral sides of the CA3, CA1, somatosensory cortex, entorhinal cortex, piriform cortex, reticular nucleus, putamen, and claustrum. In Wistar rats, the CA3, CA1, somatosensory cortex, entorhinal cortex, piriform cortex, reticular nucleus, amygdala, and laterodorsal nucleus exhibited significant differences. Comparing GAERS and Wistar rats, a statistically significant difference was observed for both sides of CA1. In both groups, the staining was prominent ipsilaterally, except for the claustrum in GAERS rats. However, the motor cortex remained unaffected in both groups. Neurodegenerative changes were not associated with the severity of seizures in both groups following the intra-amygdaloid kainic acid administration. CONCLUSION: This study demonstrates that CA1 is the only region exhibiting a statistically significant difference between Wistar and GAERS rats.

Depolarisation and suppression of burst firing activity in the mouse subthalamic nucleus by dopamine D1/D5 receptor activation of a cyclic-nucleotide gated non-specific cation conductance.

Neuronal burst firing in the subthalamic nucleus (STN) is one of the hallmarks of dopamine depletion in Parkinson's disease. Here, we have determined the postsynaptic effects of dopamine in the STN and the functional consequences of dopamine receptor modulation on burst firing in vitro. STN cells displayed regular spiking activity at a rate of 7.9+/-0.5 Hz. Application of dopamine (30 microM) induced membrane depolarisations accompanied by an increase in firing rate of mean 12.0+/-0.6 Hz in all 69 cells. The dopamine effect was mimicked by the dopamine D1/D5 receptor agonist SKF38393 (10 microM, 17 cells) and the dopamine D2-like receptor agonist quinpirole (10 microM, 35 cells), partly reduced by D1/D5 antagonist SCH23390 (2 microM, seven cells), but unaffected by the D2 antagonists sulpiride (10 microM, seven cells) or eticlopride (10 microM, six cells). Using voltage ramps, dopamine induced an inward current of 69+/-9.4 pA at a holding potential of -60 mV (n=17). This current was accompanied by an increase in input conductance of 1.55+/-0.35 nS which reversed at -30.6+/-2.3 mV, an effect mimicked by SKF38393 (10 microM, nine cells). Similar responses were observed when measuring instantaneous current evoked by voltage steps and in the presence of the I(h) blocker, ZD7288, indicating effects independent of I(h). The increase in conductance was blocked by SCH23390 (2 microM, n=4), mimicked by the activator of adenylyl cyclase forskolin (10 microM, n=7) and blocked by H-89, an inhibitor of cyclic AMP dependent protein kinase A (10 microM, n=6). These results indicate that the dopamine depolarisation is in part mediated by D1/D5 receptor mediated activation of a cyclic-nucleotide gated (CNG) non-specific cation conductance. This conductance contributes to the membrane depolarisation that changes STN neuronal bursting to more regular activity by significantly increasing burst duration and number of spikes per burst.

Dopamine acting at D1-like, D2-like and α1-adrenergic receptors differentially modulates theta and gamma oscillatory activity in primary motor cortex.

The loss of dopamine (DA) in Parkinson's is accompanied by the emergence of exaggerated theta and beta frequency neuronal oscillatory activity in the primary motor cortex (M1) and basal ganglia. DA replacement therapy or deep brain stimulation reduces the power of these oscillations and this is coincident with an improvement in motor performance implying a causal relationship. Here we provide in vitro evidence for the differential modulation of theta and gamma activity in M1 by DA acting at receptors exhibiting conventional and non-conventional DA pharmacology. Recording local field potentials in deep layer V of rat M1, co-application of carbachol (CCh, 5 µM) and kainic acid (KA, 150 nM) elicited simultaneous oscillations at a frequency of 6.49 ± 0.18 Hz (theta, n = 84) and 34.97 ± 0.39 Hz (gamma, n = 84). Bath application of DA resulted in a decrease in gamma power with no change in theta power. However, application of either the D1-like receptor agonist SKF38393 or the D2-like agonist quinpirole increased the power of both theta and gamma suggesting that the DA-mediated inhibition of oscillatory power is by action at other sites other than classical DA receptors. Application of amphetamine, which promotes endogenous amine neurotransmitter release, or the adrenergic α1-selective agonist phenylephrine mimicked the action of DA and reduced gamma power, a result unaffected by prior co-application of D1 and D2 receptor antagonists SCH23390 and sulpiride. Finally, application of the α1-adrenergic receptor antagonist prazosin blocked the action of DA on gamma power suggestive of interaction between α1 and DA receptors. These results show that DA mediates complex actions acting at dopamine D1-like and D2-like receptors, α1 adrenergic receptors and possibly DA/α1 heteromultimeric receptors to differentially modulate theta and gamma activity in M1.

GABA(A) receptor mediated transmission in the thalamic reticular nucleus of rats with genetic absence epilepsy shows regional differences: functional implications.

The aim of the present study was to investigate the effect of local injections of the GABA(A) receptor antagonist, bicuculline, into the rostral and caudal parts of the thalamic reticular nucleus (TRN), on the generation of spike-and-wave discharges in Genetic Absence Epilepsy Rats from Strasbourg (GAERS). Spike-and-wave discharges are important in the pathophysiology of absence epilepsy and generated by the cortico-thalamo-cortical pathway, where GABA has a significant role, particularly in the TRN. Artificial cerebrospinal fluid or bicuculline was administered to rostral or caudal parts of TRN of GAERS through a stereotaxically placed guide cannula. Administration of bicuculline produced opposite effects according to the injection site. Administration into the caudal TRN produced statistically significant increases in the duration of spike-and-wave discharges, whereas injections into the rostral TRN produced significant decreases. Correspondingly, distinct patterns of afferent connections have been demonstrated with the wheat-germ-agglutinin horseradish peroxidase (WGA-HRP) retrograde tracing method in control non-epileptic rats and GAERS for the rostral and caudal parts of the TRN. Injection of WGA-HRP tracer showed no detectable difference regarding the rostral and caudal connections between GAERS and Wistar animals. Rostral parts of TRN have thalamic and cortical connections that are primarily motor and limbic whereas for the caudal parts these connections are primarily sensory. Further, the rostral parts receive inputs from the substantia nigra pars reticularis and the ventral pallidum that the caudal part lacks. The extent to which these connectional differences may be responsible for the functional differences demonstrated by the bicucculine injections remains to be explored.

Glutamic acid decarboxylase isoform distribution in transgenic mouse septum: an anti-GFP immunofluorescence study.

The septum is a basal forebrain region located between the lateral ventricles in rodents. It consists of lateral and medial divisions. Medial septal projections regulate hippocampal theta rhythm whereas lateral septal projections are involved in processes such as affective functions, memory formation, and behavioral responses. Gamma-aminobutyric acidergic neurons of the septal region possess the 65 and 67 isoforms of the enzyme glutamic acid decarboxylase. Although data on the glutamic acid decarboxylase isoform distribution in the septal region generally appears to indicate glutamic acid decarboxylase 67 dominance, different studies have given inconsistent results in this regard. The aim of this study was therefore to obtain information on the distributions of both of these glutamic acid decarboxylase isoforms in the septal region in transgenic mice. Two animal groups of glutamic acid decarboxylase-green fluorescent protein knock-in transgenic mice were utilized in the experiment. Brain sections from the region were taken for anti-green fluorescent protein immunohistochemistry in order to obtain estimated quantitative data on the number of gamma-aminobutyric acidergic neurons. Following the immunohistochemical procedures, the mean numbers of labeled cells in the lateral and medial septal nuclei were obtained for the two isoform groups. Statistical analysis yielded significant results which indicated that the 65 isoform of glutamic acid decarboxylase predominates in both lateral and medial septal nuclei (unpaired two-tailed t-test p < 0.0001 for LS, p < 0.01 for MS). This study is the first to reveal the dominance of glutamic acid decarboxylase isoform 65 in the septal region in glutamic acid decarboxylase-green fluorescent protein transgenic mice.

Early Onset of Atherosclerosis of The Carotid Bifurcation in Newborn Cadavers.

INTRODUCTION: The anatomy of arterial bifurcations affects blood flow and has a significant role in the development of vascular disease. Therefore, it is important to know the structural characteristics of the Common Carotid Artery (CCA) and its branches for early onset of atherosclerosis in newborns. AIM: The present study was conducted to evaluate the characteristics of CCA in newborn cadavers. MATERIALS AND METHODS: Eight carotid arteries obtained from newborn cadavers were used. The outflow to inflow area ratios was calculated to evaluate vessel diameters. Additionally, scanning electron and light microscopic investigations were conducted with tissue samples. The brachial artery of each cadaver was used as controls. Correlation between area ratios and atherosclerotic endothelial damage was determined. RESULTS: Light microscopic investigations demonstrated that control group sections showed no positivity for Oil red O staining, while carotid bifurcation regions depicted widespread occurrence of intimal lipid accumulations. Scanning electron microscopic examination of control group sections presented regular endothelial topography, while carotid bifurcation region topography exhibited numerous blood cells and separated endothelial cells. Fibrin accumulation on endothelial surface in low area ratios was another important finding in the examination of its endothelial surface degeneration. The above-mentioned morphological findings seemed to be quite parallel to outflow to inflow area ratio data favouring low area and degeneration. CONCLUSION: The correlation between area ratios and the histological characteristic of cerebral vessels of newborn cadavers indicate that early stages of atherosclerosis began in early embryologic life.

Morphometric characteristics of caudal cranial nerves at petroclival region in fetuses.

Morphometric measurements of cranial nerves in posterior cranial fossa of fetus cadavers were carried out in an attempt to identify any asymmetry in their openings into the cranium. Twenty-two fetus cadavers (8 females, 14 males) with gestational age ranging between 22 and 38 weeks (mean 30 weeks) were included in this study. The calvaria were removed, the brains were lifted, and the cranial nerves were identified. The distance of each cranial nerve opening to midline and the distances between different cranial nerve openings were measured on the left and right side and compared. The mean clivus length and width were 21.2 ± 4.4 and 13.2 ± 1.5 mm, respectively. The distance of the twelfth cranial nerve opening from midline was shorter on the right side when compared with the left side (6.6 ± 1.1 versus 7.1 ± 0.8 mm, p = 0.038). Openings of other cranial nerves did not show such asymmetry with regard to their distance from midline, and the distances between different cranial nerves were similar on the left and right side. Cranial nerves at petroclival region seem to show minimal asymmetry in fetuses.

Expression of NADPH-d in the vagal nuclei of the chronic esophagitis model in rats.

AIM: To evaluate the changes in the number of NADPH diaphorase (NADPH-d) stained neurons in the vagal nuclei in a chronic esophagitis model. MATERIALS AND METHODS: There were 3 groups of rats examined: 1) a chronic gastroesophageal reflux rat group, which was created by a partial gastric outlet obstruction; 2) a sham group; and 3) a ranitidine treated group. Serial sections ofbrainstems of all groups were cut and NADPH-d staining, which selectively stains the nitric acid synthase-containing neurons, was done. RESULTS: Histopathological changes due to chronic reflux esophagitis was observed in the reflux group. The ranitidine treatment and sham control groups showed no changes related to esophagitis. The staining in the dorsal motor nucleus of the vagus and nucleus tractus solitarius showed statistically significant differences compared to the control group (P < 0.0001). CONCLUSION: The increased nitric oxide expressions in the dorsal vagal nucleus and nucleus tractus solitarius are most probably due to adaptive changes to disturbed esophageal motility and mucosal damage.

Topical glucocorticoid reduces the topical decongestant-induced histologic changes in an animal model nasal mucosa.

OBJECTIVES/HYPOTHESIS: To investigate the histologic consequences of simultaneous nasal glucocorticosteroid and xylometazoline HCl administration in the rabbit nasal mucosa. STUDY DESIGN: Prospective randomized study. METHODS: Twenty New Zealand male rabbits were randomly placed into three groups: group I, control (n = 6); group II, xylometazoline HCl (n = 8); or group III, xylometazoline HCl-fluticasone furoate (n = 6). Group I received no treatment. Groups II and III received two intranasal puffs of xylometazoline HCl 0.5 mg/mL twice daily or two puffs of xylometazoline HCl 0.5 mg/mL twice daily plus one puff of 27.5 µg fluticasone furoate twice daily to each nostril (110 µg), respectively. At the end of 3 weeks, the rabbits were sacrificed. The mucosa of the nasal cavities was excised. Specimen sections (5 µm) were stained with hematoxylin and eosin, mucicarmine, and Gomori one-step trichrome and were examined under a light microscope. The presence of edema, congestion, inflammatory cell infiltration, nasociliary loss, epithelial and nerve-ending degeneration, and goblet cell increase were evaluated semiquantitatively (grades 0-3). RESULTS: Statistically significant differences were detected between groups II and III in terms of edema, congestion, inflammatory cell infiltration, nasociliary loss, and epithelial degeneration (P = .006, P = .049, P = .015, P = .014, and P = .049, respectively). Nerve-ending degeneration, goblet cell increase, and quantitative goblet and neutrophil cell counts did not yield statistically significant differences between groups II and III (P = .137, P = .580, P = .770, and P = .616, respectively). CONCLUSIONS: The combined simultaneous intranasal administration of xylometazoline HCl and fluticasone furoate appears to be beneficial in minimizing the long-term usage-associated congestion, edema, inflammatory cell infiltration, epithelial degeneration, and nasociliary loss in the rabbit model nasal mucosa.

The diameters of common carotid artery and its branches in newborns.

The common carotid artery (CCA) bifurcation is of clinical importance due to its vascular access site for intravascular intervention. Additionally, it is also one of the most common sites of atherosclerotic plaque formation. There are numerous studies on the diameters of CCA, internal carotid artery (ICA), and external carotid artery (ECA) in adults, but few studies on newborns. Cadaver and angiographic studies have shown dimensional variations in the carotid arteries within/between individuals and also between different sexes. It is well known that the initial lesions of atherosclerosis begin very early in fetal life. Therefore, it is important to know the anatomical details of the CCA and its branches. In the present study, the neck regions of 20 (11 males and 9 females) fixed newborn cadavers were dissected. The CCAs were cut below the bulb of the carotid bifurcation further; ICA and ECA were cut above the bulb of the carotid bifurcation. The internal diameters of the CCA, ICA, and ECA were measured using a light microscopy. ECA/CCA, ICA/CCA, ICA/ECA ratios, and outflow to inflow area ratio were calculated. The mean outflow to inflow area ratio was 1.14+/-0.28. Our results highly correlated with the defined optimal ratio (1.15). The ECA/CCA, ICA/CCA, and ICA/ECA ratios were 0.78+/-0.12, 0.71+/-0.13, and 0.93+/-0.16, respectively. There were no statistically significant differences between male and female and also between right and left sides. These findings are of importance in understanding the anatomy of carotid artery during newborn period.

Attitudes of Turkish anatomists toward cadaver donation.

There is an insufficient number of cadavers in anatomy education in Turkey. This is because of decreased number of unclaimed bodies and very few cadaver donations. Increasing the number of cadaver donation is one of the probable solutions. Although anatomists encourage people to donate bodies, the attitudes of anatomists toward donating their own bodies for dissection is not well known. In this study, the attitudes of Turkish anatomists toward cadaver donation were evaluated. The questionnaires were sent to the anatomists in Turkey by mail and E-mail. Eighty-three anatomists replied to the questionnaire. The main solutions proposed for cadaver insufficiency included increasing the supply of unclaimed bodies (77.1%) and increasing body donation (78.3%). Further, 51.8% of the respondents thought that increasing body donation was a long-term solution. The general belief (83.1%) was that a campaign would help to increase body donation and 47% of respondents were willing to participate in such a campaign. Of the 83 anatomists, 20.5% of the respondents donated their organs and 49.4% were planning to donate them. Further, 15.7% were planning to donate their bodies; however, 63.9% did not consider donating. The main reasons of the respondents to object the donation were: to be dissected by a colleague (15.7%), the unacceptability of donation by family (26.5%), psychological reasons (43.4%), the anxiety of disrespectful behavior to cadavers (26.5%), and religious beliefs (3.6%). Although the majority of the respondents objected to donating their bodies due to psychological reasons, body donation was proposed as the main solution of cadaver insufficiency.

Connections of the dorsomedial hypothalamic nucleus from the forebrain structures in the rat.

The dorsomedial hypothalamic nucleus (DMH) has been implicated as an area controlling autonomic activity. The aim of this study was to demonstrate connections of the anterior and posterior DMH to the forebrain structures, using a horseradish peroxidase (HRP) retrograde axonal transport technique in rats. The results of HRP labelling show that the anterior and posterior DMH indicate a number of differences in their connections. The posterior DMH has intense connections with the cortex (cingulate, frontal, parietal and insular), amygdala (lateral and basolateral) and hippocampus (CA1 and CA2), whereas the anterior DMH has faint connections with the cortex (cingulate, frontal and parietal) and prominent connections with the septal and bed nucleus of stria terminalis. These differences in connections of the DMH may provide sites for the specific autonomic function integrated by the DMH.

Cerebellar connections to the rostral reticular nucleus of the thalamus in the rat.

We studied the cerebellar connections to the reticular nucleus thalamus (RNT) by means of retrograde axonal transport of horseradish peroxidase (HRP) in the rat. Specific HRP pressure injections to the rostral RNT (1.6-1.8 mm caudal to bregma) resulted in retrograde labelling of neurones in the cerebellar nuclei. The rostral RNT showed specific topographical organization of its cerebellar connections. Microinjections into the rostral RNT, 1.6 mm caudal to bregma, produced numerous HRP-labelled neurones within the anterior interposed (emboliform nucleus) and scarce HRP-labelled neurones within the lateral (dentate nucleus) cerebellar nuclei, whereas injections into the rostral RNT, 1.8 mm caudal to bregma, produced numerous HRP-labelled neurones within the posterior interposed (globose nucleus) and scarce lightly HRP-labelled neurones within the lateral (dentate nucleus) cerebellar nuclei. Cerebellar connections with the rostral RNT were exclusively ipsilateral to the injection site. No HRP-labelled cells were detected in the medial (fastigial nucleus) cerebellar nucleus. The cerebellar connections reach the RNT via the superior cerebellar peduncle. By contrast, HRP injections into the anterior, posterior interposed and lateral cerebellar nuclei produced no labelled cells within the RNT. This study demonstrates the existence of direct cerebello-RNT but not RNT-cerebellar connections. The presence of the cerebello-RNT connections introduces a new route through which the cerebellum may influence RNT and thus cerebral cortical activity.