scholarly journals Region-specific maladaptive gray matter myelination is associated with differential susceptibility to stress-induced behavior in male rodents and humans

2021 ◽  
Author(s):  
Kimberly L. P. Long ◽  
Linda L. Chao ◽  
Yurika Kazama ◽  
Anjile An ◽  
Kelsey Y. Hu ◽  
...  
Keyword(s):  
Gray Matter ◽  
Traumatic Stress ◽  
Adult Brain ◽  
Fear Learning ◽  
Male Rats ◽  
Adult Rats ◽  
Behavioral Variation ◽  
Weighted Estimates ◽  
Functional Changes ◽  
Symptom Profiles

AbstractBackgroundIndividual reactions to traumatic stress vary dramatically, yet the biological basis of this variation remains poorly understood. Recent studies have demonstrated surprising plasticity of oligodendrocytes and myelin in the adult brain, providing a potential mechanism by which aberrant structural and functional changes arise in the brain following trauma exposure.MethodsWe tested the hypothesis that gray matter myelin contributes to traumatic stress-induced behavioral variation. We exposed adult rats to a single, severe stressor and used a multimodal approach to characterize avoidance, startle, and fear-learning behavior. We quantified oligodendrocyte and myelin content in multiple brain areas and compared these measures to behavioral metrics. We then induced overexpression of the oligodendrogenic transcription factor Olig1 in the adult rat dentate gyrus (DG) to test the potential, causal role of oligodendrogenesis in behavioral variation. Lastly, T1-/T2-weighted estimates of myelin were compared to trauma-induced symptom profiles in humans.ResultsOligodendrocytes and myelin in the DG of the hippocampus positively correlated with stress-induced avoidance behaviors in male rats. In contrast, myelin levels in the amygdala positively correlated with contextual fear learning. Olig1 overexpression increased place avoidance compared to control virus animals, indicating that increased oligodendrocyte drive in the DG is sufficient to induce an avoidance behavioral phenotype. Finally, variation in myelin correlated with trauma-induced symptom profiles in humans in a region-specific manner that mirrored our rodent findings.ConclusionsThese results demonstrate a species-independent relationship between region-specific, gray matter oligodendrocytes and myelin and differential behavioral phenotypes following traumatic stress exposure. This study provides a novel biological framework for understanding the mechanisms that underlie individual variance in sensitivity to traumatic stress.

scholarly journals Regional gray matter oligodendrocyte- and myelin-related measures are associated with differential susceptibility to stress-induced behavior in rats and humans

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kimberly L. P. Long ◽  
Linda L. Chao ◽  
Yurika Kazama ◽  
Anjile An ◽  
Kelsey Y. Hu ◽  
...  
Keyword(s):  
Dentate Gyrus ◽  
Gray Matter ◽  
Traumatic Stress ◽  
Brain Plasticity ◽  
Differential Susceptibility ◽  
Adult Brain ◽  
Fear Learning ◽  
Male Rats ◽  
Functional Changes ◽  
Specific Manner

AbstractIndividual reactions to traumatic stress vary dramatically, yet the biological basis of this variation remains poorly understood. Recent studies demonstrate the surprising plasticity of oligodendrocytes and myelin with stress and experience, providing a potential mechanism by which trauma induces aberrant structural and functional changes in the adult brain. In this study, we utilized a translational approach to test the hypothesis that gray matter oligodendrocytes contribute to traumatic-stress-induced behavioral variation in both rats and humans. We exposed adult, male rats to a single, severe stressor and used a multimodal approach to characterize avoidance, startle, and fear-learning behavior, as well as oligodendrocyte and myelin basic protein (MBP) content in multiple brain areas. We found that oligodendrocyte cell density and MBP were correlated with behavioral outcomes in a region-specific manner. Specifically, stress-induced avoidance positively correlated with hippocampal dentate gyrus oligodendrocytes and MBP. Viral overexpression of the oligodendrogenic factor Olig1 in the dentate gyrus was sufficient to induce an anxiety-like behavioral phenotype. In contrast, contextual fear learning positively correlated with MBP in the amygdala and spatial-processing regions of the hippocampus. In a group of trauma-exposed US veterans, T1-/T2-weighted magnetic resonance imaging estimates of hippocampal and amygdala myelin associated with symptom profiles in a region-specific manner that mirrored the findings in rats. These results demonstrate a species-independent relationship between region-specific, gray matter oligodendrocytes and differential behavioral phenotypes following traumatic stress exposure. This study suggests a novel mechanism for brain plasticity that underlies individual variance in sensitivity to traumatic stress.

scholarly journals Alcohol and Vapourized Nicotine Co-Exposure During Adolescence Contribute Differentially to Sex-Specific Behavioural Effects in Adulthood

2021 ◽  
Author(s):  
Jessica Ruffolo ◽  
Jude Frie ◽  
Hayley Thorpe ◽  
Malik Talhat ◽  
Jibran Khokhar
Keyword(s):  
Alcohol Drinking ◽  
Preference Test ◽  
Alcohol Preference ◽  
Female Rats ◽  
Fear Learning ◽  
Male Rats ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Male And Female ◽  
Male And Female Rats

Introduction: Co-occurrence of e-cigarette use and alcohol consumption during adolescence is frequent. However, little is known about their long-lasting effects when combined. Here, we examined whether adolescent co-exposure to alcohol drinking and vapourized nicotine would impact reward- and cognition-related behaviours in adult male and female rats during adulthood. Methods: Four groups of male and female Sprague Dawley rats (n=8-11/group/sex) received either nicotine (JUUL 5% nicotine pods) or vehicle vapour daily between postnatal days 30-46, while having continuous voluntary access to ethanol and water during this time in a two-bottle preference design. Upon reaching adulthood, rats underwent behavioural testing utilizing Pavlovian conditioned approach testing, fear conditioning and a two-bottle alcohol preference test. Results: A sex-dependent effect was found in the two-bottle preference test in adulthood such that females had a higher intake and preference for alcohol compared to males regardless of adolescent exposure; both male and female adult rats had greater alcohol preference compared to adolescents. Male rats exposed to vapourized nicotine with or without alcohol drinking during adolescence exhibited altered reward-related learning in adulthood, evidenced by enhanced levels of sign-tracking behaviour. Male rats that drank alcohol with or without nicotine vapour in adolescence showed deficits in associative fear learning and memory as adults. In contrast, these effects were not seen in female rats exposed to alcohol and nicotine vapour during adolescence. Conclusions: The present study provides evidence that co-exposure to alcohol and vapourized nicotine during adolescence in male, but not female, rats produces long-term changes in reward- and cognition-related behaviours.

scholarly journals Juvenile exposure to acute traumatic stress leads to long-lasting alterations in grey matter myelination in adult female but not male rats

2020 ◽  
Author(s):  
Jocelyn M Breton ◽  
Matthew Barraza ◽  
Kelsey Y Hu ◽  
Samantha Joy Frias ◽  
Kimberly L.P. Long ◽  
...  
Keyword(s):  
Traumatic Stress ◽  
Grey Matter ◽  
Acute Stress ◽  
Brain Regions ◽  
Adult Brain ◽  
Female Rats ◽  
Male Rats ◽  
Stress Exposure ◽  
Corticosterone Release

Stress early in life can have a major impact on brain development, and there is increasing evidence that childhood stress confers vulnerability for later developing psychiatric disorders. In particular, during peri-adolescence, brain regions crucial for emotional regulation, such as the prefrontal cortex (PFC), amygdala (AMY) and hippocampus (HPC), are still developing and are highly sensitive to stress. Changes in myelin levels have been implicated in mental illnesses and stress effects on myelin and oligodendrocytes (OLs) are beginning to be explored as a novel and underappreciated mechanism underlying psychopathologies. Yet there is little research on the effects of acute stress on myelin during peri-adolescence, and even less work exploring sex-differences. Here, we used a rodent model to test the hypothesis that exposure to acute traumatic stress as a juvenile would induce changes in OLs and myelin content across limbic brain regions. Male and female juvenile rats underwent three hours of restraint stress with exposure to a predator odor on postnatal day (p) 28. Acute stress induced a physiological response, increasing corticosterone release and reducing weight gain in stress-exposed animals. Brain sections containing the PFC, AMY and HPC were taken either in adolescence (p40), or in adulthood (p95) and stained for markers of OLs and myelin. We found that acute stress induced sex-specific changes in grey matter (GM) myelination and OLs in both the short- and long-term. Exposure to a single stressor as a juvenile increased GM myelin content in the AMY and HPC in p40 males, compared to the respective control group. At p40, corticosterone release during stress exposure was also positively correlated with GM myelin content in the AMY of male rats. Single exposure to juvenile stress also led to long-term effects exclusively in female rats. Compared to controls, stress-exposed females showed reduced GM myelin content in all three brain regions. Acute stress exposure decreased PFC and HPC OL density in p40 females, perhaps contributing towards this observed long-term decrease in myelin content. Overall, our findings suggest that the juvenile brain is vulnerable to exposure to a brief severe stressor. Exposure to a single short traumatic event during peri-adolescence produces long-lasting changes in GM myelin content in the adult brain of female, but not male, rats. These findings highlight myelin plasticity as a potential contributor to sex-specific sensitivity to perturbation during a critical window of development.

INDUCTION OF GOITRE BY PTU OR KClO4 IN MALE AND FEMALE RATS. EFFECT OF GONADECTOMY

1973 ◽  
Vol 74 (1) ◽  
pp. 88-104 ◽  
Author(s):  
T. Jolín ◽  
M. J. Tarin ◽  
M. D. Garcia
Keyword(s):  
Iodine Content ◽  
High Plasma ◽  
Disc Electrophoresis ◽  
Female Rats ◽  
Male Rats ◽  
Adult Rats ◽  
Male And Female ◽  
Glucose Levels ◽  
Male And Female Rats ◽  
Tsh Levels

ABSTRACT Male and female rats of varying ages were placad on a low iodine diet (LID) plus KClO4 or 6-propyl-2-thiouracil (PTU) or on the same diet supplemented with I (control rats). Goitrogenesis was also induced with LID plus PTU in gonadectomized animals of both sexes. The weight of the control and goitrogen treated animals, and the weight and iodine content of their thyroids were determined, as well as the plasma PBI, TSH, insulin and glucose levels. The pituitary GH-like protein content was assessed by disc electrophoresis on polyacrylamide gels. If goitrogenesis was induced in young rats of both sexes starting with rats of the same age, body weight (B.W.) and pituitary growth hormone (GH) content, it was found that both the males and females developed goitres of the same size. On the contrary, when goitrogenesis was induced in adult animals, it was found that male rats, that had larger B.W. and pituitary GH content than age-paired females, developed larger goitres. However, both male and female rats were in a hypothyroid condition of comparable degree as judged by the thyroidal iodine content and the plasma PBI and TSH levels. When all the data on the PTU or KClO4-treated male and female rats of varying age and B.W. were considered together, it was observed that the weights of the thyroids increased proportionally to B.W. However, a difference in the slope of the regression of the thyroid weight over B.W. was found between male and female rats, due to the fact that adult male rats develop larger goitres than female animals. In addition, in the male rats treated with PTU, gonadectomy decreased the B.W., pituitary content of GH-like protein and, concomitantly, the size of the goitre decreased; an opposite effect was induced by ovariectomy on the female animals. However, when goitrogenesis was induced in weight-paired adult rats of both sexes, the male animals still developed larger goitres than the females. Among all the parameters studied here, the only ones which appeared to bear a consistent relationship with the size of the goitres in rats of different sexes, treated with a given goitrogen, were the rate of body growth and the amount of a pituitary GH-like protein found before the onset of the goitrogen treatment. Moreover, though the pituitary content of the GH-like protein decreased as a consequence of goitrogen treatment, it was still somewhat higher in male that in female animals. The present results suggest that GH may somehow be involved in the mechanism by which male and female rats on goitrogens develop goitres of different sizes, despite equally high plasma TSH levels.

scholarly journals Transfer of rhodamine-123 into the brain and cerebrospinal fluid of fetal, neonatal and adult rats

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Liam M. Koehn ◽  
Katarzyna M. Dziegielewska ◽  
Mark D. Habgood ◽  
Yifan Huang ◽  
Norman R. Saunders
Keyword(s):  
Cerebrospinal Fluid ◽  
Fetal Brain ◽  
Maternal Blood ◽  
Adult Brain ◽  
Rhodamine 123 ◽  
Patient Specific ◽  
Adult Rats ◽  
Blood Brain ◽  
The Brain ◽  
Brain Barriers

Abstract Background Adenosine triphosphate binding cassette transporters such as P-glycoprotein (PGP) play an important role in drug pharmacokinetics by actively effluxing their substrates at barrier interfaces, including the blood-brain, blood-cerebrospinal fluid (CSF) and placental barriers. For a molecule to access the brain during fetal stages it must bypass efflux transporters at both the placental barrier and brain barriers themselves. Following birth, placental protection is no longer present and brain barriers remain the major line of defense. Understanding developmental differences that exist in the transfer of PGP substrates into the brain is important for ensuring that medication regimes are safe and appropriate for all patients. Methods In the present study PGP substrate rhodamine-123 (R123) was injected intraperitoneally into E19 dams, postnatal (P4, P14) and adult rats. Naturally fluorescent properties of R123 were utilized to measure its concentration in blood-plasma, CSF and brain by spectrofluorimetry (Clariostar). Statistical differences in R123 transfer (concentration ratios between tissue and plasma ratios) were determined using Kruskal-Wallis tests with Dunn’s corrections. Results Following maternal injection the transfer of R123 across the E19 placenta from maternal blood to fetal blood was around 20 %. Of the R123 that reached fetal circulation 43 % transferred into brain and 38 % into CSF. The transfer of R123 from blood to brain and CSF was lower in postnatal pups and decreased with age (brain: 43 % at P4, 22 % at P14 and 9 % in adults; CSF: 8 % at P4, 8 % at P14 and 1 % in adults). Transfer from maternal blood across placental and brain barriers into fetal brain was approximately 9 %, similar to the transfer across adult blood-brain barriers (also 9 %). Following birth when placental protection was no longer present, transfer of R123 from blood into the newborn brain was significantly higher than into adult brain (3 fold, p < 0.05). Conclusions Administration of a PGP substrate to infant rats resulted in a higher transfer into the brain than equivalent doses at later stages of life or equivalent maternal doses during gestation. Toxicological testing of PGP substrate drugs should consider the possibility of these patient specific differences in safety analysis.

Abstract 403: Renal Denervation Reveals Renal Sympathetic Activation in Adult Rats Exposed to Early Life Stress

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Analia S Loria ◽  
Michael W Brands ◽  
David M Pollock ◽  
Jennifer S Pollock
Keyword(s):  
Life Stress ◽  
Early Life ◽  
Renal Denervation ◽  
Early Life Stress ◽  
Male Rats ◽  
Renal Nerves ◽  
Adult Rats ◽  
Baseline Conditions ◽  
Control Sham ◽  
Renal Sympathetic

We previously reported that maternal separation (MS), a model of early life stress, does not modify baseline blood pressure in adult rats, but increases sensitivity to hypertensive stimuli. Under baseline conditions, adult male rats exposed to MS have significantly reduced glomerular filtration rate (GFR). Acute phenylephrine-induced reductions in renal blood flow is significantly attenuated in rats exposed to MS compared to control rats. Furthermore, norephinephrine (NE) content was increased in renal cortex of MS rats compared to control rats (p<0.05). These data indicate that MS induces increased renal sympathetic outflow. Thus, we hypothesized that renal denervation will normalize GFR in rats exposed to MS. Male WKY rat pups were separated from their mothers for 3 hrs/day during the morning hours from day 2 to 14 of life. Male non-separated littermates served as control rats. Experiments were performed in 300-320 g adult rats. Denervation (DnX) was performed mechanically stripping all visible renal nerves followed by topical phenol (10%) on the renal artery. Control-sham, MS-sham, control-DnX, and MS-DnX rats were instrumented with catheters in the femoral vein and abdominal aorta. Rats were placed in metabolic cages, connected to swivels, and allowed to recover for 4-5 days. Sodium intake was clamped at 2.8 mEq/day in both groups by combining sodium deficient diet and 24 hr/day 0.9% iv saline infusion (20 ml/day). GFR was determined by plasma clearance of [125I]iothalamate in the conscious state. During baseline conditions, MAP was not different between control-sham and MS-sham rats (99±4 vs 97±2 mmHg, respectively). MAP was reduced in both control-DnX and MS-DnX rats (91±2 mmHg and 83±3 mmHg, p<0.05, respectively) compared with the respective sham group. The reduction in MAP tended to be greater in MS than in control rats (-9±1 and -14±2 mmHg, p=0.074). DnX did not modify GFR in control rats (sham: 3.1±0.1 ml/min vs DnX: 3.5±0.4 ml/min). However, DnX significantly increased GFR in rats exposed to MS (sham: 2.4±0.2 ml/min vs DnX: 3.8±0.4 ml/min, p<0.05). These data support our hypothesis that MS induces increased renal sympathetic tone to reduce GFR in MS male rats, and may contribute to the exacerbated response to hypertensive stimuli observed in MS rats.

Regulation of parathyroid hormone secretion by plasma calcium in aging rats

1991 ◽  
Vol 260 (2) ◽  
pp. E220-E225 ◽  
Author(s):  
J. Fox
Keyword(s):  
Parathyroid Hormone ◽  
Hormone Secretion ◽  
Fold Increase ◽  
Male Rats ◽  
Aged Rats ◽  
Adult Rats ◽  
Dihydroxyvitamin D3 ◽  
Set Point ◽  
Skeletal Resistance ◽  
Immunoreactive Parathyroid Hormone

Plasma immunoreactive parathyroid hormone (irPTH) levels increase with aging. This study determined 1) whether NH2-terminal irPTH secretory responses to induced hypocalcemia differ between adult (6-mo-old) and aged (24- to 26-mo-old) male rats and 2) whether a higher set point for irPTH release by Ca is responsible for the elevated irPTH levels with aging. Basal irPTH levels were 68% higher and 1,25-dihydroxyvitamin D3 levels were 44% lower in aged rats. An acutely induced, constant hypocalcemic stimulus [0.32 mM decrement in ionized Ca (Ca2+) for 2 h] was developed in catheterized conscious adult and aged rats by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) infusion using the Ca clamp technique. The initial irPTH secretory response to acute hypocalcemia (5-10 min) was reduced in aged rats (1.9- vs. 3.1-fold increase), suggesting reduced hormone stores. However, higher sustained irPTH levels (30 min to 2 h) were maintained in aged rats, indicating increased irPTH synthesis and release. The EGTA infusion rate necessary to maintain constant hypocalcemia was less in aged rats, suggesting skeletal resistance to PTH. Slow EGTA and Ca infusions were used to determine irPTH secretion at plasma Ca2+ levels from 0.7 to 1.5 mM. In aged rats, irPTH levels were higher at all Ca2+ concentrations, but the set point for irPTH release by Ca2+ was the same as in adult rats. Thus the elevated irPTH secretion in aged rats is not caused by a change in the set point for irPTH release but does result in decreased irPTH stores.

Time course of hemodynamic changes in rats with healed severe myocardial infarction

1989 ◽  
Vol 257 (1) ◽  
pp. H289-H296 ◽  
Author(s):  
A. DeFelice ◽  
R. Frering ◽  
P. Horan
Keyword(s):  
Myocardial Infarction ◽  
Blood Flow ◽  
Cardiac Output ◽  
Diastolic Pressure ◽  
Weight Ratio ◽  
Left Ventricular ◽  
Male Rats ◽  
Coronary Artery Ligation ◽  
Sham Operation ◽  
Functional Changes

Male rats were monitored for 8 mo after severe myocardial infarction (MI) to chronicle hemodynamic and left ventricular (LV) functional changes. Blood pressure (BP), heart rate (HR), cardiac output index (CO), regional blood flow, and systemic vascular resistance (SVR) were measured with catheters and radiolabeled microspheres at 4, 7, 10, 20, and 35 wk after coronary artery ligation (n = 10–16/group) or sham operation (control; n = 9–14/group). At 4 wk, 43 +/- 1% of the LV circumference was scarred, peak LV BP, LV dP/dtmax, mean BP, SVR, and HR were 11–38% less than control (P less than 0.05), and LV end-diastolic pressure (LVEDP) was increased by 313% (P less than 0.05). Mean BP, LVEDP, LVBP, and LV dP/dtmax did not further deviate after 4 wk. However, CO and SVR changed progressively and were 67 and 33%, respectively, of control by 35 wk (P less than 0.05) when blood flow to stomach, small intestine, and kidney was 55, 38, and 27% of control. Lung and heart weights were significantly increased by 148 and 22% at 4 wk, and remained elevated, and lung dry weight-to-wet weight ratio was reduced at 7 and 10 wk. Thus the trajectory of rats with healed severe MI reflects progressive cardiac decompensation, cardiac output redistribution, and terminal heart failure.

Developmental changes in passive stiffness and myofilament Ca2+ sensitivity due to titin and troponin-I isoform switching are not critically triggered by birth

2006 ◽  
Vol 291 (2) ◽  
pp. H496-H506 ◽  
Author(s):  
Martina Krüger ◽  
Thomas Kohl ◽  
Wolfgang A. Linke
Keyword(s):  
Guinea Pig ◽  
Heart Development ◽  
Troponin I ◽  
Collagen Matrix ◽  
Passive Stiffness ◽  
Adult Rats ◽  
Functional Changes ◽  
Fetal Rat ◽  
Isoform Switching ◽  
Species Specific

The giant protein titin, a major contributor to myocardial mechanics, is expressed in two main cardiac isoforms: stiff N2B (3.0 MDa) and more compliant N2BA (>3.2 MDa). Fetal hearts of mice, rats, and pigs express a unique N2BA isoform (∼3.7 MDa) but no N2B. Around birth the fetal N2BA titin is replaced by smaller-size N2BA isoforms and N2B, which predominates in adult hearts, stiffening their sarcomeres. Here we show that perinatal titin-isoform switching and corresponding passive stiffness (STp) changes do not occur in the hearts of guinea pig and sheep. In these species the shift toward “adult” proportions of N2B isoform is almost completed by midgestation. The relative contributions of titin and collagen to STp were estimated in force measurements on skinned cardiac muscle strips by selective titin proteolysis, leaving the collagen matrix unaffected. Titin-based STp contributed between 42% and 58% to total STp in late-fetal and adult sheep/guinea pigs and adult rats. However, only ∼20% of total STp was titin based in late-fetal rat. Titin-borne passive tension and the proportion of titin-based STp generally scaled with the N2B isoform percentage. The titin isoform transitions were correlated to a switch in troponin-I (TnI) isoform expression. In rats, fetal slow skeletal TnI (ssTnI) was replaced by adult carciac TnI (cTnI) shortly after birth, thereby reducing the Ca2+ sensitivity of force development. In contrast, guinea pig and sheep coexpressed ssTnI and cTnI in fetal hearts, and skinned fibers from guinea pig showed almost no perinatal shift in Ca2+ sensitivity. We conclude that TnI-isoform and titin-isoform switching and corresponding functional changes during heart development are not initiated by birth but are genetically programmed, species-specific regulated events.

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