Gert J. Ter Horst

Anatomical and functional demonstration of a multisynaptic suprachiasmatic nucleus adrenal (cortex) pathway

In view of mounting evidence that the suprachiasmatic nucleus (SCN) is directly involved in the setting of sensitivity of the adrenal cortex to ACTH, the present study investigated possible anatomical and functional connections between SCN and adrenal. Transneuronal virus tracing from the adrenal revealed first order labelling in neurons in the intermedio‐lateral column of the spinal cord that were shown to receive an input from oxytocin fibres and subsequently second‐order labelling in neurons of the autonomic division of the paraventricular nucleus. The latter neurons were shown to receive an input from vasopressin or vasoactive intestinal peptide (VIP) containing SCN efferents. The true character of this SCN input to second‐order neurons was also demonstrated by the fact that third‐order labelling was present within the SCN, vasopressin or VIP neurons. The functional presence of the SCN–adrenal connection was demonstrated by a light‐induced fast decrease in plasma corticosterone that could not be attributed to a decrease in ACTH. Using intact and SCN‐lesioned animals, the immediate decrease in plasma corticosterone was only observed in intact animals and only at the beginning of the dark period. This fast decrease of corticosterone was accompanied by constant basal levels of blood adrenaline and noradrenaline, and is proposed to be due to a direct inhibition of the neuronal output to the adrenal cortex by light‐mediated activation of SCN neurons. As a consequence, it is proposed that the SCN utilizes neuronal pathways to spread its time of the day message, not only to the pineal, but also to other organs, including the adrenal, utilizing the autonomic nervous system.

rCBF differences between panic disorder patients and control subjects during anticipatory anxiety and rest

BACKGROUND Our goal was to identify brain structures involved in anticipatory anxiety in panic disorder (PD) patients compared to control subjects. METHODS Seventeen PD patients and 21 healthy control subjects were studied with H(2)(15)O positron emission tomography scan, before and after a pentagastrin challenge. RESULTS During anticipatory anxiety we found hypoactivity in the precentral gyrus, the inferior frontal gyrus, the right amygdala, and the anterior insula in PD patients compared to control subjects. Hyperactivity in patients compared to control subjects was observed in the parahippocampal gyrus, the superior temporal lobe, the hypothalamus, the anterior cingulate gyrus, and the midbrain. After the challenge, the patients showed decreases compared to the control subjects in the precentral gyrus, the inferior frontal gyrus, and the anterior insula. Regions of increased activity in the patients compared to the control subjects were the parahippocampal gyrus, the superior temporal lobe, the anterior cingulate gyrus, and the midbrain. CONCLUSIONS The pattern of regional cerebral blood flow activations and deactivations we observed both before and after the pentagastrin challenge was the same, although different in intensity. During anticipatory anxiety more voxels were (de)activated than during rest after the challenge.

Dynamics of cerebral tissue injury and perfusion after temporary hypoxia-ischemia in the rat : evidence for region-specific sensitivity and delayed damage

BACKGROUND AND PURPOSE Selective regional sensitivity and delayed damage in cerebral ischemia provide opportunities for directed and late therapy for stroke. Our aim was to characterize the spatial and temporal profile of ischemia-induced changes in cerebral perfusion and tissue status, with the use of noninvasive MRI techniques, to gain more insight in region-specific vulnerability and delayed damage. METHODS Rats underwent 20 minutes of unilateral cerebral hypoxia-ischemia (HI). We performed combined repetitive quantitative diffusion-weighted, T2-weighted, and dynamic susceptibility contrast-enhanced MRI from before HI to 5 hours after HI. Data were correlated with parallel blood oxygenation level-dependent MRI and laser-Doppler flowmetry. Finally, MRI and histology were done 24 and 72 hours after HI. RESULTS Severe hypoperfusion during HI caused acute reductions of the apparent diffusion coefficient (ADC) of tissue water in the ipsilateral hemisphere. Reperfusion resulted in dynamic perfusion alterations that varied spatially. The ADC recovered completely within 1 hour in the hippocampus (from 0.68 +/- 0.07 to 0.83 +/- 0.09 x 10[-3] mm2/s), cortex (from 0.56 +/- 0.06 to 0.77 +/- 0.07 x 10[-3] mm2/s), and caudate putamen (from 0.58 +/- 0.06 to 0.75 +/- 0.06 x 10[-3] mm2/s) but only partially or not at all in the thalamus (from 0.65 +/- 0.07 to 0.68 +/- 0.12 x 10[-3] mm2/s) and substantia nigra (from 0.80 +/- 0.08 to 0.76 +/- 0.10 x 10[-3] mm2/s). Secondary ADC reductions, accompanied by significant T2 elevations and histological damage, were observed after 24 hours. Initial and secondary ADC decreases were observed invariably in the hippocampus, cortex, and caudate putamen and in approximately 70% of the animals in the thalamus and substantia nigra. CONCLUSIONS Region-specific responses and delayed ischemic damage after transient HI were demonstrated by MRI. Acute reperfusion-induced normalization of ADCs appeared to poorly predict ultimate tissue recovery since secondary, irreversible damage developed eventually.

Neuroanatomy of Cardiac Activity-regulating Circuitry: A Transneuronal Retrograde Viral Labelling Study in the Rat

The anatomy of cardiac activity‐regulating circuitry was studied with retrograde transneuronal viral labelling after pseudorabies virus injections into different parts of the rat heart. Transection of the spinal cord at Th1 was used to reveal selectively the parasympathetic neuronal networks. Virus‐labelled sympathetic preganglionic cells were found in the Th1‐Th7 thoracic intermediolateral cell groups, with some additional infections at Th8‐Thll after inoculations of the ventricular myocardium. After ventricular injections the thoracic spinal labelling pattern was bilateral and after right atrial infection it was contralateral. Approximately 20% of the parasympathetic preganglionic cells were located in the dorsal motor vagus nucleus; the rest occupied positions in the peri‐ambiguus area ventrolateral to the nucleus ambiguus. Here and in the ventrolateral reticular formation myocardiotopy was found. Supraspinal transneuronal infections were bilateral, showed no apparent side dominance and were found in the nucleus of the solitary tract, the area postrema, the raphe nuclei, the A5 group, the parabrachial region, the periaqueductal grey, the hypothalamus, the amygdala and the cortex, in particular the anterior cingulate, the frontal, prelimbic, infralimbic and insular cortices. Spinal transections at Th1 reduced the number of labelled cells, gave a right side labelling dominance and affected the infection patterns in the ventrolateral reticular area, the raphe nuclei, the periaqueductal grey matter, the perifornical and retrochiasmatic area and the rostra1 parts of the insular cortex. The latter structures are linked selectively to the sympathetic innervation of the heart. The anatomical and functional aspects of these findings are discussed in relation to the autonomic control of heart activity.

Dose-response characteristics of ketamine effect on locomotion, cognitive function and central neuronal activity

The present dose-response study sought to determine the effects of subanesthetic dosages (4-16 mg/kg) of ketamine on locomotion, sensorimotor gating (PPI), working memory, as well as c-fos expression in various limbic regions implicated in the pathogenesis of schizophrenia. In addition, we examined whether ketamine-induced locomotion was influenced by the dark/light cycle. We found that ketamine increased locomotor activity in a dose dependent manner, but found no influence of the dark-light cycle. Additionally, ketamine dose-dependently interrupted PPI, resulting in prepulse facilitation at doses of 8 and 12 mg/kg. The dose of 12 mg/kg also induced impairments in working memory assessed by the discrete-trial delayed-alternation task. C-fos expression indicated that the dose-dependent behavioral effects of ketamine might be related to changes in the activity of limbic regions, notably hippocampus and amygdala.

Sex differences in stress responses: Focus on ovarian hormones

Women in the reproductive age are more vulnerable to develop affective disorders than men. This difference may attribute to anatomical differences, hormonal influences and environmental factors such as stress. However, the higher prevalence in women normalizes once menopause is established, suggesting that ovarian hormones may play an important role in the development of depression in women. Ovarian hormones such as estrogen can pass the brain-blood barrier and bind to cytoplasmatic estrogen receptor (ER)-alpha and ER-beta in different areas of the limbic system. During stress, estrogen can modulate the behavioral and neurobiological response depending on the concentrations of estrogen. In this review we present evidence for disparate effects of chronic stress on neuroplasticity and brain activity in male and female rats. Furthermore, we will demonstrate that effects of social support on coping with stress can be mimicked by social housing of rats and that this model can be used for identification of underlying neurobiological mechanisms, including behavior, phosphorylation of CREB and ERK1/2, and brain activity changes as measured with fos expression. Using cyclic administration of estrogen in ovariectomized female rats we could specifically address effects of different plasma estrogen levels and antidepressants on stress-induced neuroplasticity and activity changes. In this model we also studied effects of estrogen on recovery after chronic stress. We conclude that the female brain has a different innate strategy to handle stress than the male brain and that female animal models are necessary for studying the underlying mechanisms and options for treatment.

Effect of metformin on left ventricular function after acute myocardial infarction in patients without diabetes: the GIPS-III randomized clinical trial

IMPORTANCE Metformin treatment is associated with improved outcome after myocardial infarction in patients with diabetes. In animal experimental studies metformin preserves left ventricular function. OBJECTIVE To evaluate the effect of metformin treatment on preservation of left ventricular function in patients without diabetes presenting with ST-segment elevation myocardial infarction (STEMI). DESIGN, SETTING, AND PARTICIPANTS Double-blind, placebo-controlled study conducted among 380 patients who underwent primary percutaneous coronary intervention (PCI) for STEMI at the University Medical Center Groningen, The Netherlands, between January 1, 2011, and May 26, 2013. INTERVENTIONS Metformin hydrochloride (500 mg) (n = 191) or placebo (n = 189) twice daily for 4 months. MAIN OUTCOMES AND MEASURES The primary efficacy measure was left ventricular ejection fraction (LVEF) after 4 months, assessed by magnetic resonance imaging. A secondary efficacy measure was the N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration after 4 months. The incidence of major adverse cardiac events (MACE; the combined end point of death, reinfarction, or target-lesion revascularization) was recorded until 4 months as a secondary efficacy measure. RESULTS At 4 months, all patients were alive and none were lost to follow-up. LVEF was 53.1% (95% CI, 51.6%-54.6%) in the metformin group (n = 135), compared with 54.8% (95% CI, 53.5%-56.1%) (P = .10) in the placebo group (n = 136). NT-proBNP concentration was 167 ng/L in the metformin group (interquartile range [IQR], 65-393 ng/L) and 167 ng/L in the placebo group (IQR, 74-383 ng/L) (P = .66). MACE were observed in 6 patients (3.1%) in the metformin group and in 2 patients (1.1%) in the placebo group (P = .16). Creatinine concentration (79 µmol/L [IQR, 70-87 µmol/L] vs 79 µmol/L [IQR, 72-89 µmol/L], P = .61) and glycated hemoglobin (5.9% [IQR, 5.6%-6.1%] vs 5.9% [IQR, 5.7%-6.1%], P = .15) were not significantly different between both groups. No cases of lactic acidosis were observed. CONCLUSIONS AND RELEVANCE Among patients without diabetes presenting with STEMI and undergoing primary PCI, the use of metformin compared with placebo did not result in improved LVEF after 4 months. The present findings do not support the use of metformin in this setting. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01217307.

Urinary free cortisol excretion in elderly persons with minor and major depression

Several studies have found that cortisol hypersecretion may occur in severely depressed patients, characterized by melancholic features. On the other hand, illness chronicity seems to be related to low, rather than high, cortisol levels. This study aims to trace factors associated with 24-h urinary free cortisol levels in a sample of 23 elderly persons with major or minor depression and 21 non-depressed control subjects. Depressive episodes were subdivided according to severity and chronicity (i.e. length and recurrence). None of the depressed persons showed unusually high 24-h cortisol levels, and cortisol excretion was not elevated as compared with that in the control group, regardless of subtype of depression. The results suggest, however, that hyposecretion of cortisol may be a feature of chronic depressive episodes, especially in males.

l-Deprenyl Reduces Brain Damage in Rats Exposed to Transient Hypoxia-Ischemia

BACKGROUND AND PURPOSE L-Deprenyl (Selegiline) protects animal brains against toxic substances such as 1-methyl-1,2,3,6-tetrahydropyridine and 6-hydroxydopamine. Experiments were conducted to test whether L-deprenyl prevents or reduces cerebral damage in a transient hypoxia/ischemia rat model. METHODS Rats were treated for 14 days with 2 mg/kg and 10 mg/kg L-deprenyl or saline. After surgery a 20-minute hypoxia/ischemia period was induced by simultaneous occlusion of the left common carotid artery and reduction of the percentage of oxygen in the gas mixture to 10%. Rats were killed 24 hours later. Silver staining was used to reveal damage in several brain regions. RESULTS In the brain, both L-deprenyl dosages reduced damage up to 78% compared with the controls. Total brain damage was decreased from 23%-31% to 5%-9% with the L-deprenyl treatment (2 mg/kg: F1.13 = 6.956, P < .05; 10 mg/kg: F1.13 = 5.731, P < .05). In the striatum, significant treatment effects were found between both the L-deprenyl groups (2 mg/kg and 10 mg/kg, respectively) and the saline group (F1.13 = 14.870, P < .005; and F1.13 = 8.937, P = .01; respectively). In the thalamus, significant treatment effects were seen in the 2-mg/kg L-deprenyl group (F1.13 = 11.638, P < .005) and the 10-mg/kg group (F1.13 = 8.347, P < .05) compared with the control group. No significant damage decrease was seen in the hippocampus and the cortex. CONCLUSIONS The results show that L-deprenyl is effective as a prophylactic treatment for brain tissue when it is administered before hypoxia/ischemia. Mechanisms responsible for the observed protection remain unclear. The regional differences in damage, however, are in accordance with the reported regional increase in superoxide dismutase and catalase activities after L-deprenyl treatment, suggesting the involvement of free radicals and scavenger enzymes.

DIFFERENTIAL FOS-PROTEIN INDUCTION IN RAT FOREBRAIN REGIONS AFTER ACUTE AND LONG-TERM HALOPERIDOL AND CLOZAPINE TREATMENT

Both acute and long-term effects of haloperidol and clozapine on Fos-like immunoreactive nuclei in several rat forebrain areas were quantified. Rats were treated with saline (1 ml/kg.day, control), haloperidol (1 mg/kg.day) and clozapine (20 mg/kg.day) i.p. for 21 days. Two hours before perfusion fixation a single (acute treatment) or last (long-term treatment) dose of the drug was given. Drug-induced catalepsy and gain in body weight were also measured. A single dose of haloperidol produced large increases in Fos-like immunoreactive nuclei in the striatum, the nucleus accumbens and central amygdala. Following long-term treatment these increases were reduced in all nuclei studied, except the lateral septum. Acute clozapine treatment had slight (if any) effects on the number of Fos-like immunoreactivity-expressing nuclei in the striatum, but the increases in the nucleus accumbens, the lateral septum, the paraventricular and supraoptic nuclei of the hypothalamus and the central amygdala were substantial. Long-term clozapine treatment reduced the acute response significantly in all the areas except the nucleus accumbens. Both haloperidol and clozapine treatment reduced the weight gain of the rats. Haloperidol, but not clozapine, induced catalepsy that remained maximal during the long-term haloperidol treatment. These results indicate that in most brain areas high Fos-protein levels are not necessary to maintain antipsychotic activity or side-effects. The persisting effect of clozapine in the nucleus accumbens may be of significance to the efficacy of this drug in treatment-refractory schizophrenia.