Missing Mama

1. Missing Mama Long-Lasting Effects of Maternal Separation on an Animal Model of Post-Traumatic Stress Disorder: Effects on Memory and Hippocampal Oxidative Stress

3. Long-Lasting Effects of Maternal Separation on an Animal Model of Post-Traumatic Stress Disorder: Effects on Memory and Hippocampal Oxidative Stress Underlying Assumptions • “Adverse early life events, such as maternal separation, may alter the normal pattern of brain development and subsequently the vulnerability to a variety of mental disorders in adulthood.” • Study sought to confirm prior research, which suggested that patients with a history of early life stressors show a higher frequency of Post-Traumatic Stress Disorder (PTSD).

4. Long-Lasting Effects of Maternal Separation on an Animal Model of Post-Traumatic Stress Disorder: Effects on Memory and Hippocampal Oxidative Stress • Would frequent and long-term separation from dams affect the oxidative stress parameters and memory of pups after exposure to an animal model of PTSD? • How does maternal separation affect HPA-axis maturation during perinatal programming?

5. Long-Lasting Effects of Maternal Separation on an Animal Model of Post-Traumatic Stress Disorder: Effects on Memory and Hippocampal Oxidative Stress Signs & Symptoms of PTSD Status/Post Exposure to Traumatic Event • Avoidance of stimuli associated with the trauma • Increased symptoms of autonomic arousal and re-experiencing the trauma • Pathological replay of the traumatic emotional stimuli formed in response to painful, life-threatening, or horrifying events.

7. Long-Lasting Effects of Maternal Separation on an Animal Model of Post-Traumatic Stress Disorder: Effects on Memory and Hippocampal Oxidative Stress Procedure • Nests of Wistar rats were divided into two groups, intact and subjected (MS) • Further subdivided into exposed and unexposed (unavoidable electric shock) • Spatial memory tested in Morris Water Maze • Animal participants sacrificed to assess hippocampal volume, enzyme levels, and DNA breaks.

8. Morris Water Maze

9. Long-Lasting Effects of Maternal Separation on an Animal Model of Post-Traumatic Stress Disorder: Effects on Memory and Hippocampal Oxidative Stress Antioxidant Enzymes Activities • Superoxide Dismutase Activity (SOD determined using a RANSOD kit) • Catalase Activity (CAT activity assessed based upon the degradation rate of H₂O₂) • Glutathione Peroxidase Activity (GPx expressed as nmol NADPH oxidized per minute per mg protein) Protein Assay also assessed. No difference was noted in antioxidant enzymes activities between animal model groups.

11. Long-Lasting Effects of Maternal Separation on an Animal Model of Post-Traumatic Stress Disorder: Effects on Memory and Hippocampal Oxidative Stress

12. Long-Lasting Effects of Maternal Separation on an Animal Model of Post-Traumatic Stress Disorder: Effects on Memory and Hippocampal Oxidative Stress Findings Periodic maternal separation may increase the susceptibility to the effects of a stressor applied in adulthood on performance in the water maze. Increased DNA breaks in the hippocampus were induced by both maternal separation and exposure to shock. Neonatal MS leads to an altered stress responsive phenotype and neuroendangerment Majority of hippocampal granule neurons develop and extend their axons in the first 21 days of life. Thus, overlap occurs with the stress hyporesponsive period of neurogenesis (between 4-14 days s/p birth). Exposure to a stressor may cause an adverse release of corticosterone, thereby affecting hippocampal development. Glucocorticoids may affect hippocampal development by influencing the neurogenesis – apoptosis balance in granule neurons. Some studies have linked PTSD to hippocampal atrophy and the resulting affects on the HPA-axis

13. Gender Differences in Animal Models of PTSD • Breslau et al. found that the overall conditional vulnerability for PTSD among those exposed to a potential traumatic experience (PTE) is approximately twofold higher in women than in men. • There is evidence to suggest a higher susceptibility to PTSD in women than in men. However, there is no consensus on differences in the lifetime average of traumatic events between the two genders. • Subjective evidence shows a higher likelihood that women will be victim to a PTE event than men. Previous studies also indicate that women may process a PTE differently than men. Therefore, increased susceptibility may result from the combined effects of higher lifetime PTE exposure, gender differences in neurological processing, and resulting effects on the hippocampus and HPA-axis. Further research into the influence of culture and western gender roles should be undertaken in order to gain a big-picture view of PTSD in women. • This study reviewed numerous animal model studies on basal conditions and stress responses and presents them from behavioral, neurochemical, neurobiological, and pharmacological positions in an effort to uncover binary gender differences related to PTSD.

14. Gender Differences in Animal Models of PTSD • No known studies intentionally and systematically attempt to compare male vs. female animals with regard to stress response and PTSD. Additionally, female animals are often avoided in behavioral research to avoid introducing additional biochemical variables, which may invalidate research findings (or at the very least render them suspect). • Gender differences: unstressed adult animals • Higher plasma corticosterone concentrations in resting female animals • Female animals show higher mean levels of plasma and corticosteroids during studies of 24-hr circadian rhythm gender differences (females with mature ovaries vs. intact males). • Gender differences (attributed to gonadal steroid hormone milieu) in HPA-axis function are suggested. • Higher levels of plasma and adrenal corticosterone observed proestrus suggest that estrogens may primarily influence female-type circadian rhythm.

15. Gender Differences in Animal Models of PTSD • Gender differences in response to stressors • Positive correlation between exposure to stressors and gender specific response of the HPA-axis. • Studies have yielded conclusive evidence which shows that female rats react to stressors with markedly higher and more persistent corticosterone levels s/p stressful event. Could prolonged corticosterone response affect PTSD susceptibility? • Female rats also show greater adrenocorticotrophic (ACTH) response to stress than males. • Estrogen causes prolonged adrenocorticosterone secretion. This may be due to estrogen impairment of glucocorticoid receptor-mediated negative feedback which in-turn enhances the stress response. • Recent findings suggest that estradiol exerts its action at the paraventricular nucleus via ERα-mediated disruption of GR-mediated negative feedback. • Conversely, studies utilizing gonadectomized or neonatally estrogenized rats research by Patchev et al. and McCormick et al. showed that female rats exhibit higher HPA-axis response to stress in females independent of circulating gonadal steroid levels. This may suggest innate or organized differences in HPA-axis response to stress between intact binary gender models.

16. Gender Differences in Animal Models of PTSD • Studies using hamsters conducted by Gaskin and Kitay demonstrated that the gonads influence hypothalamic and pituitary regulation of adrenocortical function. • Male- Exogenous testosterone enhances ACTH secretion, which leads to increased adrenal steroid secretion and increased hepatic metabolism of cortisol. This suggests that testosterone normally acts to inhibit the HPA response to environmental perturbation. These results were later replicated utilizing intact male F344 rats. • Gender differences have also been reported in sympathoadrenal system reactivity • Female adrenal gland is more reactive to foot-shock or novel environment. • Stress exposure produces larger increments of plasma DOPA and DOPAC in females, which indicates that tyrosine hydroxylase in sympathetic nerve terminals and adrenal medulla may also be higher in females than males.

17. Gender Differences in Animal Models of PTSD • Molecular Signaling • Gender differences in the expression of p-CREB in the PFC and DG s/p foot-shock event. Significant reduction in p-CREB immunoreactivity in a time-dependent manner in male DG two hours s/p exposure to stress box. Acute stress had no significant effect on the expression of p-CREB in female PFC and DG. • Conclusion • Gender-related differences can be demonstrated on the phenotypic and/or the endophenotypic under baseline conditions and in response to stress. • Gender-related differences in the regulation of the HPA-axis have been established • Gender differences of the CNS may have an underlying genetic component • Male animals are significantly more vulnerable to acute and chronic stress, whereas females are far more resilient. However, this is in direct contrast with data collected on PTSD with human subjects.

18. Noradrenergic Enhancement of Reconsolidation in the Amygdala Impairs Extinction of Conditioned Fear in Rats – A Possible Mechanism for the Persistence of Traumatic Memories in PTSD. Follow up to a previous study which found that noradrenergic blockade in the rat amygdala impairs reconsolidation of fear memories. Current study investigates the effects of noradrenergic enhancement on the reconsolidation of learned fear. Norepinephrine indicated in normal and pathological fear and anxiety through its involvement in fear learning and memory. Moreover, norepinephrine’s role in in the enhanced memory consolidation processes that transform new learning into long-term memory is significant. Blockade of noradrenergic transmission by the administration of the β-adrenergic receptor antagonist propranolol following trauma decreases the risk of PTSD. Clinical research indicates that the persistence and severity of PTSD symptoms is also associated with noradrenergic activity long after the traumatic event. Norepinephrine may be involved in the maintenance and exacerbation of symptoms in addition to the role it plays with initial coding.

19. Noradrenergic Enhancement of Reconsolidation in the Amygdala Impairs Extinction of Conditioned Fear in Rats – A Possible Mechanism for the Persistence of Traumatic Memories in PTSD. • Study involved Pavlovian fear conditioning using a rodent model. The goal of the study is to assess the significance of fear-learning in PTSD and other anxiety pathologies. • Fear-conditioning • A neutral event (conditioned stimulus, CS) such as a tone is paired with a noxious event (unconditioned stimulus, US) such as unavoidable foot-shock. • Key structure involved in fear-conditioning is the lateral nucleus of the amygdala (LA). This is due to informational convergence about CS and US in the LA. • Norepinephrine in the LA is involved in the acquisition, extinction, and reconsolidation of auditory-fear-conditioning. • Reconsolidation is a process whereby consolidated memories are rendered labile and susceptible to modification. • Study sought to examine whether enhancing β-adrenergic transmission augments reconsolidation of auditory-fear-conditioning.

20. Noradrenergic Enhancement of Reconsolidation in the Amygdala Impairs Extinction of Conditioned Fear in Rats – A Possible Mechanism for the Persistence of Traumatic Memories in PTSD. • Adult male Sprague-Dawley rats were implanted bilaterally with a 22 ga stainless guide cannulae aimed at the lateral nuclei of the amygdala or 2mm dorsal of the LA. • Isoproterenol (ISO) and propranolol (PRO) were both dissolved in saline (6.25 μg/μl). Drugs were infused through an infusion cannulae at 25 μl/min using a pump. A total volume of .2 μl of ISO, PRO, or an equivalent amount of saline vehicle was infused bilaterally into the LA. • Apparatus and Stimuli • Auditory fear-conditioning conducted in chamber A • Plexiglass chamber with metal grid floor that was dimly lit by single light source and enclosed within a sound attenuating chamber. • Memory reactivation and testing conducted in chamber B • Distinct conditioning plexiglass chamber located in a different room, brightly illuminated by three light sources. Floor of chamber was a flat Formica floor lightly scented with peppermint soap.

21. Noradrenergic Enhancement of Reconsolidation in the Amygdala Impairs Extinction of Conditioned Fear in Rats – A Possible Mechanism for the Persistence of Traumatic Memories in PTSD. • CS= 30-sec, 5kHz, 75-dB tone • US= 1.0-mA, 1-sec foot-shock

22. Noradrenergic Enhancement of Reconsolidation in the Amygdala Impairs Extinction of Conditioned Fear in Rats – A Possible Mechanism for the Persistence of Traumatic Memories in PTSD.

23. Noradrenergic Enhancement of Reconsolidation in the Amygdala Impairs Extinction of Conditioned Fear in Rats – A Possible Mechanism for the Persistence of Traumatic Memories in PTSD.

24. Noradrenergic Enhancement of Reconsolidation in the Amygdala Impairs Extinction of Conditioned Fear in Rats – A Possible Mechanism for the Persistence of Traumatic Memories in PTSD. Conclusions • Noradrenergic augmentation in the amygdala following retrieval of a traumatic memory enhances memory reconsolidation and makes memory less susceptible to fear extinction. • High possibility that norepinephrine-modulated reconsolidation processes contribute to the length and severity of PTSD symptoms.