scholarly journals Hippocampal Neurogenesis, Depressive Disorders, and Antidepressant Therapy

2007 ◽  
Vol 2007 ◽  
pp. 1-7 ◽  
Author(s):  
Eleni Paizanis ◽  
Michel Hamon ◽  
Laurence Lanfumey

There is a growing body of evidence that neural stem cells reside in the adult central nervous system where neurogenesis occurs throughout lifespan. Neurogenesis concerns mainly two areas in the brain: the subgranular zone of the dentate gyrus in the hippocampus and the subventricular zone, where it is controlled by several trophic factors and neuroactive molecules. Neurogenesis is involved in processes such as learning and memory and accumulating evidence implicates hippocampal neurogenesis in the physiopathology of depression. We herein review experimental and clinical data demonstrating that stress and antidepressant treatments affect neurogenesis in opposite direction in rodents. In particular, the stimulation of hippocampal neurogenesis by all types of antidepressant drugs supports the view that neuroplastic phenomena are involved in the physiopathology of depression and underlie—at least partly—antidepressant therapy.

2021 ◽  
Vol 15 ◽  
Author(s):  
Jia-Qi Ai ◽  
Rongcan Luo ◽  
Tian Tu ◽  
Chen Yang ◽  
Juan Jiang ◽  
...  

Doublecortin (DCX) is transiently expressed in new-born neurons in the subventricular zone (SVZ) and subgranular zone (SGZ) related to adult neurogenesis in the olfactory bulb (OB) and hippocampal formation. DCX immunoreactive (DCX+) immature neurons also occur in the cerebral cortex primarily over layer II and the amygdala around the paralaminar nucleus (PLN) in various mammals, with interspecies differences pointing to phylogenic variation. The tree shrews (Tupaia belangeri) are phylogenetically closer to primates than to rodents. Little is known about DCX+ neurons in the brain of this species. In the present study, we characterized DCX immunoreactivity (IR) in the forebrain of Chinese tree shrews aged from 2 months- to 6 years-old (n = 18). DCX+ cells were present in the OB, SVZ, SGZ, the piriform cortex over layer II, and the amygdala around the PLN. The numerical densities of DCX+ neurons were reduced in all above neuroanatomical regions with age, particularly dramatic in the DG in the 5–6 years-old animals. Thus, DCX+ neurons are present in the two established neurogenic sites (SVZ and SGZ) in the Chinese tree shrew as seen in other mammals. DCX+ cortical neurons in this animal exhibit a topographic pattern comparable to that in mice and rats, while these immature neurons are also present in the amygdala, concentrating around the PLN as seen in primates and some nonprimate mammals.


1975 ◽  
Vol 20 (12) ◽  
pp. 923-924
Author(s):  
MADGE E. SCHEIBEL ◽  
ARNOLD B. SCHEIBEL

2020 ◽  
Vol 44 (3) ◽  
pp. 241-249
Author(s):  
Yoshiaki Omura

While a visiting Professor at the University of Paris, VI (formerly Sorvonne) more than 40 years ago, the Author became very good friends with Dr. Paul Nogier who periodically gave seminars and workshops in Paris. After the author diagnosed his cervical problem & offered him simple help, Dr. Nogier asked the Author to present lectures and demonstrations on the effects of ear stimulation, namely the effects of acupuncture & electrical stimulation of the ear lobules. It is only now, in 2019 that we have discovered 2–5 minute high frequency stimulation of the ear lobule inhibits cancer activity for 1– 4 hours post stimulation. Although the procedure is extremely simple. First take optimal dose of Vitamin D3, which has the most essential 10 unique beneficial factors required for every human cell activity. Next, apply high frequency stimulation to ear lobule while the worst ear lobule is held by all fingers with vibrator directly touching the surface of the worst ear lobule, preferably after patient repeatedly takes optimal dose of Vitamin D3. When the worst ear lobule is held between thumb & index fingers and applying mechanical stimulation of 250 ~ 500 mechanical vibration/second for 2 ~ 5 minutes using an electrical vibrator, there is rapid disappearance of cancer activity in both the brain and rest of the body for short time duration 1 ~ 4 hours. The effect often increases by additional pressure by holding fingers. As of May 2019, the Author found that many people from various regions of the world developed early stages of multiple cancers. For evaluation of this study, U. S. patented Bi-Digital O-Ring Test (BDORT) was used which was developed by the Author while doing his Graduate experimental physics research at Colombia University. BDORT was found to be most essential for determining the beneficial effects as well as harmful effects of any substance or treatment. Using BDORT, Author was the first to recognize severe increasing mid-backache was an early sign of pancreatic cancer of President of New York State Board of Medicine after top pain specialists failed to detect the cause after 3 years of effort, while the BDORT showed early stages of cancer whereas conventional X-Ray of the pancreas did not show any cancer image until 2 months after Author detected with BDORT. For example, the optimal dose of the banana is usually about 2.0 - 2.5 millimeters cross section of the banana. A whole banana is more than 50 ~ 100 times the optimal dose. Any substance eaten in more than 25 times of its optimal dose becomes highly toxic and creates DNA mutations which can cause multiple malignancies in the presence of strong electro-magnetic field. With standard medication given by doctor, patients often become sick and they are unable to reduce body weight, unless medication is reduced or completely stopped. When the amount of zinc is very high, DNA often becomes unstable and multiple cancers can grow rapidly in the presence of strong electromagnetic field. Large amount of Vitamin C from regular orange or orange juice inhibit the most important Vitamin D3 effects. At least 3 kinds of low Vitamin C oranges will not inhibit Vitamin D3. Since B12 particularly methyl cobalamin which is a red small tablet is known to improve brain circulation very significantly we examined its effect within 20 seconds of oral intake we found the following very significant changes. Acetylcholine in both sides of the brain often increases over 4,500 ng. Longevity gene Sirtuin 1 level increases significantly for short time of few hours. Thymosin α1 and Thymosinβ4 both increase to over 1500 ng from 20 ng or less.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Danilo Reymão Moreira ◽  
Ana Carolina Musa Gonçalves Uberti ◽  
Antonio Rafael Quadros Gomes ◽  
Michelli Erica Souza Ferreira ◽  
Aline da Silva Barbosa ◽  
...  

AbstractThe present study aimed to evaluate the effects of dexamethasone on the redox status, parasitemia evolution, and survival rate of Plasmodium berghei-infected mice. Two-hundred and twenty-five mice were infected with Plasmodium berghei and subjected to stimulation or inhibition of NO synthesis. The stimulation of NO synthesis was performed through the administration of L-arginine, while its inhibition was made by the administration of dexamethasone. Inducible NO synthase (iNOS) inhibition by dexamethasone promoted an increase in the survival rate of P. berghei-infected mice, and the data suggested the participation of oxidative stress in the brain as a result of plasmodial infection, as well as the inhibition of brain NO synthesis, which promoted the survival rate of almost 90% of the animals until the 15th day of infection, with possible direct interference of ischemia and reperfusion syndrome, as seen by increased levels of uric acid. Inhibition of brain iNOS by dexamethasone caused a decrease in parasitemia and increased the survival rate of infected animals, suggesting that NO synthesis may stimulate a series of compensatory redox effects that, if overstimulated, may be responsible for the onset of severe forms of malaria.


2021 ◽  
Vol 22 (14) ◽  
pp. 7664
Author(s):  
Katarzyna Bartkowska ◽  
Krzysztof Turlejski ◽  
Beata Tepper ◽  
Leszek Rychlik ◽  
Peter Vogel ◽  
...  

Shrews are small animals found in many different habitats. Like other mammals, adult neurogenesis occurs in the subventricular zone of the lateral ventricle (SVZ) and the dentate gyrus (DG) of the hippocampal formation. We asked whether the number of new generated cells in shrews depends on their brain size. We examined Crocidura russula and Neomys fodiens, weighing 10–22 g, and Crocidura olivieri and Suncus murinus that weigh three times more. We found that the density of proliferated cells in the SVZ was approximately at the same level in all species. These cells migrated from the SVZ through the rostral migratory stream to the olfactory bulb (OB). In this pathway, a low level of neurogenesis occurred in C. olivieri compared to three other species of shrews. In the DG, the rate of adult neurogenesis was regulated differently. Specifically, the lowest density of newly generated neurons was observed in C. russula, which had a substantial number of new neurons in the OB compared with C. olivieri. We suggest that the number of newly generated neurons in an adult shrew’s brain is independent of the brain size, and molecular mechanisms of neurogenesis appeared to be different in two neurogenic structures.


2021 ◽  
Vol 14 ◽  
pp. 117864692110031
Author(s):  
Marion Falabrègue ◽  
Anne-Claire Boschat ◽  
Romain Jouffroy ◽  
Marieke Derquennes ◽  
Haidar Djemai ◽  
...  

Low levels of the neurotransmitter serotonin have been associated with the onset of depression. While traditional treatments include antidepressants, physical exercise has emerged as an alternative for patients with depressive disorders. Yet there remains the fundamental question of how exercise is sensed by the brain. The existence of a muscle–brain endocrine loop has been proposed: according to this scenario, exercise modulates metabolization of tryptophan into kynurenine within skeletal muscle, which in turn affects the brain, enhancing resistance to depression. But the breakdown of tryptophan into kynurenine during exercise may also alter serotonin synthesis and help limit depression. In this study, we investigated whether peripheral serotonin might play a role in muscle–brain communication permitting adaptation for endurance training. We first quantified tryptophan metabolites in the blood of 4 trained athletes before and after a long-distance trail race and correlated changes in tryptophan metabolism with physical performance. In parallel, to assess exercise capacity and endurance in trained control and peripheral serotonin–deficient mice, we used a treadmill incremental test. Peripheral serotonin–deficient mice exhibited a significant drop in physical performance despite endurance training. Brain levels of tryptophan metabolites were similar in wild-type and peripheral serotonin–deficient animals, and no products of muscle-induced tryptophan metabolism were found in the plasma or brains of peripheral serotonin–deficient mice. But mass spectrometric analyses revealed a significant decrease in levels of 5-hydroxyindoleacetic acid (5-HIAA), the main serotonin metabolite, in both the soleus and plantaris muscles, demonstrating that metabolization of tryptophan into serotonin in muscles is essential for adaptation to endurance training. In light of these findings, the breakdown of tryptophan into peripheral but not brain serotonin appears to be the rate-limiting step for muscle adaptation to endurance training. The data suggest that there is a peripheral mechanism responsible for the positive effects of exercise, and that muscles are secretory organs with autocrine-paracrine roles in which serotonin has a local effect.


1999 ◽  
Vol 14 (2) ◽  
pp. 93-100
Author(s):  
J. Catteau ◽  
C. Cyran ◽  
R. Bordet ◽  
C.E. Thomas ◽  
B.A. Dupuis

SummaryThe goal of this prospective investigation was to study the course and the quality of patient-psychiatrist relationships during phase II / phase III clinical trials of antidepressant medication prescribed for depressive disorders. All patients who participated in the clinical trials (and subsequently in this survey) signed written informed consent statements and were subject to random double blind treatment assignment. Retrospective analysis of 118 investigations was carried out, and the patients involved were questioned concerning their experiences and impressions during and after the study. Data show that the outcome of clinical trials of antidepressant drugs are not a function of pre-existing good patient-psychiatrist relationships. On the other hand, no effects on the patient-psychiatrist relationship were found as a result of the experimental procedure, and it can be concluded that no detrimental effects on future patient-psychiatrist relationships were incurred.


2015 ◽  
Vol 37 (2) ◽  
pp. 115-130 ◽  
Author(s):  
Beth A. Costine ◽  
Symeon Missios ◽  
Sabrina R. Taylor ◽  
Declan McGuone ◽  
Colin M. Smith ◽  
...  

Stimulation of postnatal neurogenesis in the subventricular zone (SVZ) and robust migration of neuroblasts to the lesion site in response to traumatic brain injury (TBI) is well established in rodent species; however, it is not yet known whether postnatal neurogenesis plays a role in repair after TBI in gyrencephalic species. Here we describe the anatomy of the SVZ in the piglet for the first time and initiate an investigation into the effect of TBI on the SVZ architecture and the number of neuroblasts in the white matter. Among all ages of immaturity examined the SVZ contained a dense mesh network of neurogenic precursor cells (doublecortin+) positioned directly adjacent to the ependymal cells (ventricular SVZ, Vsvz) and neuroblasts organized into chains that were distinct from the Vsvz (abventricular SVZ, Asvz). Though the architecture of the SVZ was similar among ages, the areas of Vsvz and Asvz neuroblast chains declined with age. At postnatal day (PND) 14 the white matter tracts have a tremendous number of individual neuroblasts. In our scaled cortical impact model, lesion size increased with age. Similarly, the response of the SVZ to injury was also age dependent. The younger age groups that sustained the proportionately smallest lesions had the largest SVZ areas, which further increased in response to injury. In piglets that were injured at 4 months of age and had the largest lesions, the SVZ did not increase in response to injury. Similar to humans, swine have abundant gyri and gyral white matter, providing a unique platform to study neuroblasts potentially migrating from the SVZ to the lesioned cortex along these white matter tracts. In piglets injured at PND 7, TBI did not increase the total number of neuroblasts in the white matter compared to uninjured piglets, but redistribution occurred with a greater number of neuroblasts in the white matter of the hemisphere ipsilateral to the injury compared to the contralateral hemisphere. At 7 days after injury, less than 1% of neuroblasts in the white matter were born in the 2 days following injury. These data show that the SVZ in the piglet shares many anatomical similarities with the SVZ in the human infant, and that TBI had only modest effects on the SVZ and the number of neuroblasts in the white matter. Piglets at an equivalent developmental stage to human infants were equipped with the largest SVZ and a tremendous number of neuroblasts in the white matter, which may be sufficient in lesion repair without the dramatic stimulation of neurogenic machinery. It has yet to be determined whether neurogenesis and migrating neuroblasts play a role in repair after TBI and/or whether an alteration of normal migration during active postnatal population of brain regions is beneficial in species with gyrencephalic brains.


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