The effects of chronic stress on hippocampal morphology and function: An evaluation of chronic restraint paradigms

McLaughlin, Katie J.; Gómez, Juan L.; Baran, Sarah E.; Conrad, Cheryl D.

doi:10.1016/j.brainres.2007.05.042

Cited by 279 publications

(205 citation statements)

References 73 publications

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“…Resilience and vulnerability were defined based on a well-established biological index of stress, adrenal gland weight (Selye, 1936;Bassett and Cairncross, 1975;Dallman, 1984;Ottenweller et al, 1989;Marquez et al, 2004), and cross checked by EPM and body weight. EPM and body weight are both validated measures of effects of repeated stress in vulnerable rats (Willner et al, 1996;Stone and Quartermain, 1997;Caldji et al, 2000;Maslova et al, 2002;Vyas et al, 2002;Marquez et al, 2004;Weiss et al, 2004;McLaughlin et al, 2007;Pohl et al, 2007;Zhang and Rosenkranz, 2012), further validating the subdivision of populations.…”

Section: Discussionmentioning

confidence: 99%

Distinct Effects of Repeated Restraint Stress on Basolateral Amygdala Neuronal Membrane Properties in Resilient Adolescent and Adult Rats

Hetzel

Rosenkranz

2014

Neuropsychopharmacol

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Severe and repeated stress has damaging effects on health, including initiation of depression and anxiety. Stress that occurs during development has long-lasting and particularly damaging effects on emotion. The basolateral amygdala (BLA) plays a key role in many affective behaviors, and repeated stress causes different forms of BLA hyperactivity in adolescent and adult rats. However, the mechanism is not known. Furthermore, not every individual is susceptible to the negative consequences of stress. Differences in the effects of stress on the BLA might contribute to determine whether an individual will be vulnerable or resilient to the effects of stress on emotion. The purpose of this study is to test the cellular underpinnings for age dependency of BLA hyperactivity after stress, and whether protective changes occur in resilient individuals. To test this, the effects of repeated stress on membrane excitability and other membrane properties of BLA principal neurons were compared between adult and adolescent rats, and between vulnerable and resilient rats, using in vitro whole-cell recordings. Vulnerability was defined by adrenal gland weight, and verified by body weight gain after repeated restraint stress, and fecal pellet production during repeated restraint sessions. We found that repeated stress increased the excitability of BLA neurons, but in a manner that depended on age and BLA subnucleus. Furthermore, stress resilience was associated with an opposite pattern of change, with increased slow afterhyperpolarization (AHP) potential, whereas vulnerability was associated with decreased medium AHP. The opposite outcomes in these two populations were further distinguished by differences of anxiety-like behavior in the elevated plus maze that were correlated with BLA neuronal excitability and AHP. These results demonstrate a substrate for BLA hyperactivity after repeated stress, with distinct membrane properties to target, as well as age-dependent factors that contribute to resilience to the effects of stress.

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Section: Discussionmentioning

confidence: 99%

Distinct Effects of Repeated Restraint Stress on Basolateral Amygdala Neuronal Membrane Properties in Resilient Adolescent and Adult Rats

Hetzel

Rosenkranz

2014

Neuropsychopharmacol

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“…Previous research from our lab suggests that the traditional Y-maze task may be more sensitive to detecting changes in spatial memory of male rats relative to female rats (Conrad et al, 1996;Conrad et al, 2003;Kleen et al, 2006;McLaughlin et al, 2005;McLaughlin et al, 2007;Wright and Conrad, 2005;Wright et al, 2006;Wright and Conrad, 2008). Therefore, to make the task more challenging in this study, we modified the procedure to include longer delays (6 and 24 hours) than previously used (4 hours, Conrad et al, 1996;McLaughlin et al, 2007).…”

Section: Y-mazementioning

confidence: 99%

“…Tasks included variations of the Y-maze (Conrad et al, 1996;McLaughlin et al, 2005;McLaughlin et al, 2007), water maze (Jarrard, 1983;Morris, 1981;Morris et al, 1982), and object placement (Beck and Luine, 2002;Ennaceur et al, 1997). All rats underwent OVX and then started on a two-pulse schedule of 17β-estradiol injections (0, 5, 10µg, s.c.) at 72 and 48 hours prior to behavioral testing.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of estradiol influence on spatial tasks and hippocampal CA1 spines: Evidence that the duration of hormone deprivation after ovariectomy compromises 17β-estradiol effectiveness in altering CA1 spines

McLaughlin

Bimonte‐Nelson

Neisewander

et al. 2008

Hormones and Behavior

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Two pulses of 17β-estradiol (10µg) are commonly used to increase hippocampal CA1 apical dendritic spine density and alter spatial performance in ovariectomized (OVX) female rats, but rarely are the measures combined. The goal of this study was to use this two-pulse injection protocol repeatedly with intervening wash-out periods in the same rats to: 1) measure spatial ability using different tasks that require hippocampal function and 2) determine whether ovarian hormone depletion for an extended 10-week period reduces 17β-estradiol's effectiveness in elevating CA1 apical dendritic spine density. Results showed that two injections of 10µg 17β-estradiol (72 and 48 hrs prior to testing and timed to maximize CA1 apical spine density at behavioral assessment) corresponded to improved spatial memory performance on object placement. In contrast, two injections of 5µg 17β-estradiol facilitated spatial learning on the water maze compared to rats given two injections of 10µg 17β-estradiol or the sesame oil vehicle. Neither 17β-estradiol dose altered Y-maze performance. As expected, the intermittent two-pulse injection protocol increased CA1 apical spine density, but ten weeks of OVX without estradiol treatment decreased the effectiveness of 10µg 17β-estradiol to increase CA1 apical spine density. Moreover, two pulses of 5µg 17β-estradiol injected intermittently failed to alter CA1 apical spine density and decreased basal spine density. These results demonstrate that extended time without ovarian hormones reduces 17β-estradiol's effectiveness to increase CA1 apical spine density. Collectively, these findings highlight the complex interactions among estradiol, CA1 spine density/morphology, and task requirements, all of which contribute to behavioral outcomes.

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“…Restraint stress was induced by wrapping individual rats with a soft and flexible plastic mesh secured at the head and tail ends with metal clips as described by McLaughlin et al (2007). This prevented free mobilisation of the rats, but without imposing unnecessary pain.…”

Section: Experimental Protocolsmentioning

confidence: 99%

Evaluation of the protective effects of tocotrienol-rich fraction from palm oil on the dentate gyrus following chronic restraint stress in rats

Talip¹,

Asari

Khan³

et al. 2013

Braz. J. Pharm. Sci.

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Exposure to chronic restraint stress has been shown to cause a number of morphological changes in the hippocampal formation of rats. Tocotrienol, an isoform of vitamin E, exhibits numerous health benefits, different from those of tocopherol. Recent studies have demonstrated that tocotrienol prevents stressinduced changes in the gastric mucosa, thus indicating that it may also protect other organs such as the brain from the damaging effects of stress. Therefore, the aim of the present study was to investigate the protective effect of tocotrienol-rich fraction (TRF) extracted from palm oil on the dentate gyrus of rats following exposure to chronic restraint stress. Thirty-six male Sprague Dawley rats were divided into four groups: control, stress, tocotrienol and combination of stress and tocotrienol. Animals were stressed by restraining them for 5 hours every day for 21 consecutive days. TRF was administered via oral gavage at a dose of 200 mg/kg body weight. Our results showed that the plasma corticosterone level was significantly increased in response to stress, compared to the control. The results confirmed previous findings that chronic restraint stress suppresses cellular proliferation and reduces granule cell number in the dentate gyrus. However, TRF supplementation failed to prevent or minimize these stressinduced changes. Therefore, we conclude that TRF at the current dosage is not effective in preventing the morphological changes in the dentate gyrus induced by chronic restraint stress.Uniterms: Tocotrienol. Tocotrienol rich fraction. Restraint stress. Dentate gyrus. Hippocampus.A exposição crônica ao estresse por restrição causa série de alterações morfológicas na formação do hipocampo de ratos. Tocotrienol, uma isoforma da vitamina E, apresenta inúmeros benefícios para a saúde, diferente do tocoferol. Estudos recentes demonstraram que o tocotrienol impediu alterações induzidas por estresse na mucosa gástrica, indicando, assim, a possibilidade de que ele pode, também, proteger outros órgãos, como o cérebro, dos efeitos nocivos do estresse. Dessa forma, o objetivo do presente estudo foi investigar o efeito protetor da fração rica em tocotrienol (TRF), extraída do óleo de palma, no giro denteado após exposição crônica ao estresse por restrição. Trinta e seis ratos machos Sprague Dawley foram divididos em quatro grupos: controle, estresse, tocotrienol e combinação de estresse e tocotrienol. Os animais foram estressados por restrição, 5 horas por dia, durante 21 dias consecutivos. TRF foi administrado por gavagem oral na dose de 200 mg/kg de peso corporal. Nossos resultados mostraram que o nível de corticosterona plasmática foi significativamente aumentado em resposta ao estresse em comparação ao controle. Os resultados confirmam os achados anteriores de que o estresse por restrição suprime a proliferação celular e reduz o número de células granulares do giro denteado. No entanto, a suplementação de TRF foi ineficaz para evitar ou minimizar as alterações induzidas por estresse. Assim, concluímos que TRF na ...

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The effects of chronic stress on hippocampal morphology and function: An evaluation of chronic restraint paradigms

Cited by 279 publications

References 73 publications

Distinct Effects of Repeated Restraint Stress on Basolateral Amygdala Neuronal Membrane Properties in Resilient Adolescent and Adult Rats

Distinct Effects of Repeated Restraint Stress on Basolateral Amygdala Neuronal Membrane Properties in Resilient Adolescent and Adult Rats

Assessment of estradiol influence on spatial tasks and hippocampal CA1 spines: Evidence that the duration of hormone deprivation after ovariectomy compromises 17β-estradiol effectiveness in altering CA1 spines

Evaluation of the protective effects of tocotrienol-rich fraction from palm oil on the dentate gyrus following chronic restraint stress in rats

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