Sam Perez

Sympathetic innervation of the spleen in male Brown Norway rats: a longitudinal aging study.

Aging leads to reduced cellular immunity with consequent increased rates of infectious disease, cancer, and autoimmunity in the elderly. The sympathetic nervous system (SNS) modulates innate and adaptive immunity via innervation of lymphoid organs. In aged Fischer 344 (F344) rats, noradrenergic (NA) nerve density in secondary lymphoid organs declines, which may contribute to immunosenescence with aging. These studies suggest there is SNS involvement in age-induced immune dysregulation. The purpose of this study was to longitudinally characterize age-related change in sympathetic innervation of the spleen and sympathetic activity/tone in male Brown Norway (BN) rats, which live longer and have a strikingly different immune profile than F344 rats, the traditional animal model for aging research. Splenic sympathetic neurotransmission was evaluated between 8 and 32 months of age by assessing (1) NA nerve fiber density, (2) splenic norepinephrine (NE) concentration, and (3) circulating catecholamine levels after decapitation. We report a decline in NA nerve density in splenic white pulp (45%) at 15 months of age compared with 8-month-old (M) rats, which is followed by a much slower rate of decline between 24 and 32 months. Lower splenic NE concentrations between 15 and 32 months of age compared with 8M rats were consistent with morphometric findings. Circulating catecholamine levels after decapitation stress generally dropped with increasing age. These findings suggest there is a sympathetic-to-immune system dysregulation beginning at middle age. Given the unique T-helper-2 bias in BN rats, altered sympathetic-immune communication may be important for understanding the age-related rise in asthma and autoimmunity.

Sympathetic Nervous System and Lymphocyte Proliferation in the Fischer 344 Rat Spleen: A Longitudinal Study

Aging is associated with reduced cellular immunity, which leads to increased rates of infectious disease, cancer and autoimmunity in the elderly. Previous findings from our laboratory revealed an age-related decline in sympathetic innervation of immune organs that affects immunity. These studies suggested potential sympathetic nervous system involvement in age-induced immune dysregulation. Objectives: The purpose of this study was to longitudinally characterize the effects of age on sympathetic neurotransmission in the spleen and net sympathetic activity/tone in male Fischer 344 rats. Methods: Splenic sympathetic neurotransmission was evaluated between 8 and 24 months of age by (1) splenic norepinephrine (NE) concentration and turnover, (2) β-adrenergic receptor (β-AR) expression and (3) β-AR-stimulated splenocyte cAMP production. Measures of sympathetic neurotransmission were correlated with age-related changes in Concanavalin A (Con A)-stimulated splenocyte proliferation. Results: Splenic NE turnover increased during middle age, then subsequently declined by 18 months of age compared with 8-month-old controls (young). Splenic NE concentration increased at 10 months and decreased at 18–24 months, compared with young rats; however, plasma NE levels were not affected by age. Plasma epinephrine levels were decreased at 24 months. NE synthesis blockade increased and decreased the rate of plasma catecholamine depletion in middle and old age, respectively. β-AR-stimulated cAMP production increased in splenocytes by 15 months. An age-related decrease in Con A-induced splenocyte proliferation was apparent by 10 months and persisted through 24 months. The decline in Con A-induced splenocyte proliferation correlated with the age-related increase in cAMP production. Conclusions: Aging alters sympathetic nervous system metabolism in the spleen to affect β-AR signaling to splenocytes, suggesting that altered sympathetic-immune modulation changes are evident by early middle age.

Chronically lowering sympathetic activity protects sympathetic nerves in spleens from aging F344 rats.

In the present study, we investigated how increased sympathetic tone during middle-age affects the splenic sympathetic neurotransmission. Fifteen-month-old (M) F344 rats received rilmenidine (0, 0.5 or 1.5mg/kg/day, i.p. for 90 days) to lower sympathetic tone. Controls for age were untreated 3 or 18M rats. We report that rilmenidine (1) reduced plasma and splenic norepinephrine concentrations and splenic norepinephrine turnover, and partially reversed the sympathetic nerve loss; and (2) increased β-adrenergic receptor (β-AR) density and β-AR-stimulated cAMP production. Collectively, these findings suggest a protective effect of lowering sympathetic tone on sympathetic nerve integrity, and enhanced sympathetic neurotransmission in secondary immune organs.

Chronically reducing sympathetic activity in the spleen during middle age does not reverse the age-related increase in β-AR-stimulated cAMP production in splenocytes

complications (r = .52, p = .041). Greater depressive symptomatology and greater total mood disturbance were also significantly associated with the development of wound healing complications at the surgical site during hospitalization (r = .53, p = .041 and r = .53, p = .043, respectively). Although drawn from a modest sample size, these data suggest PNI factors may be associated with clinically significant outcomes among women who are hospitalized secondary to TAH-BSO for endometrial cancer. Our ongoing/future research will identify the relevant biobehavioral confounds in this population, as well as assess the efficacy of presurgical psychological interventions on acute postsurgical outcomes in this population.

135 EFFECTS OF AGING AND THE ANTIHYPERTENSIVE DRUG RILMENIDINE ON NERVE GROWTH FACTOR EXPRESSION IN THE SPLEEN OF MALE F344 RATS.

Previous research in our laboratory showed an age-related decline in noradrenergic (NA) sympathetic innervation of spleens from male Fischer 344 (F344) rats. Since nerve growth factor (NGF) plays an important role in determining the density of sympathetic innervation of target tissues throughout life, dysregulation of NGF expression in splenic target cells might explain the loss of sympathetic nerves. Moreover, chronically heightened sympathetic activity can also destroy nerve terminals by increased oxidative stress resulting from the breakdown of norepinephrine. The purpose of this study was to investigate whether these mechanisms are responsible for the age-related loss of splenic sympathetic nerves. Western blot analysis of NGF protein expression was evaluated in splenic lysates from untreated young (3 month) and old (18 month) male F344 rats and from 15-month-old rats treated with vehicle or rilmenidine (0.5 mg/kg and 1.5 mg/kg, bid [IP]) for 3 months to down-regulation of sympathetic activity. Our studies showed a 40% decrease in NGF protein levels in spleens from old rats compared with young adults. Noteworthy, rilmenidine induced a dose-dependent effect on NGF protein levels: administration of low and high doses of rilmenidine increased splenic NGF levels by 60 and 50%, respectively, compared with the vehicle group (sterile physiologic saline). Splenic NGF levels in the low-dose rilmenidine-treated group (500 μg/kg) were not different from those in 3-month-old F344 rats. Collectively, these findings support our hypothesis that changes in NGF protein expression might explain, at least in part, the age-related decline in sympathetic innervation of the spleen. Furthermore our data suggest that age-related changes in sympathetic activity in the spleen during middle age may precipitate the loss of NGF protein in spleens from old F344 male rats. This research is supported by NIH grant NS44032.

Effects of ageing and the antihypertensive drug rilmenidine on nerve growth factor (NGF) expression in the spleen of male F344 rats

ity to react to injury, might be of crucial importance as well. The purpose of this study was to investigate the changes in the expression of immune cells in the skin in relation to speed of wound healing and different psychological factors in humans. Twenty-two male non-smokers participated in this study. Every subject received a standard 4-mm punch biopsy. The healing process was monitored via ultrasound scanning, and the immune cells in the skin were analysed using different histological and immunohistochemical methods on the skin samples removed during the biopsy. Participants completed questionnaires on perceived stress, emotional distress, personality factors, and health behaviours 2 weeks prior, directly after and 2 weeks after the biopsy. The present study indicates the potential importance of the immune status of the skin as one of the possible pathways between psychological factors and wound healing. According to the present findings the level of activation of immune cells in the skin seems to be important in this process. Also, although in most of the analysis it failed to show statistically significant results, the expression of Langerhan’s cells deserves further investigation in this field. Macrophages showed no importance in this mechanism.

360 AGE-RELATED CHANGES IN SPLENIC NEUROTROPHIN CONTENT: A POSSIBLE CAUSE FOR DECLINING SYMPATHETIC INNERVATION IN OLD RATS

Previous research in our laboratory demonstrated an age-related decline of noradrenergic (NA) sympathetic innervation in the spleens of male Fisher 344 (F344) rats, evident by 17 months of age that was not observed in 24-month-old male Brown Norway (BN) rats. Since, the growth and maintenance of mature sympathetic neurons is dependent on the synthesis of neurotrophic factors by a variety of cell types in target organs, we hypothesized that altered neurotrophic concentrations in spleens from aged F344 rats, but not in BN rats, may account for the strain-dependent differences. To test this hypothesis, total and free nerve growth factor (NGF) and neurotrophin-3 (NT-3) concentrations in spleens from young (3-month-old) and old male F344 (24-month-old) and BN (27-month-old) rats were determined by ELISA and correlated with splenic norepinephrine concentrations. Data were expressed as means + SEM, with subsequent Students t-test performed to determine age-related difference (p≤0.05). In young adult F344 and BN rats the mean splenic concentrations of NT-3 and NGF were comparable to levels reported by other investigators. There was no effect of age on total splenic NGF concentrations (unbound + receptor bound) in either rat strain (p≥0.05). Unbound NGF concentrations in spleens from old F344 rats, and the ratio of free/bound NGF were significantly lower (p≤0.05) compared with young F344 controls. There was an age-related trend toward lower free NGF content in spleens from BN rats, but this was not statistically significant (p≥0.05). Conversely, the concentrations of free NT-3 in spleens from old F344 and BN rats were higher compared with young rats (p≤0.05). Age-associated changes in splenic neurotrophin content correlated with changes in splenic norepinephrine content. Collectively, these findings indicate altered neurotrophin expression in the aged spleen that may contribute to the previously reported strain-related differences in the density of sympathetic nerves in lymphoid compartments of the spleen with advancing age.

# 112 Strain differences in basal sympathetic activity: Effects of aging and stimulation of central imidazoline1 receptors in the rostral ventrolateral medulla

fever by 3–4 h that was maintained for at least 7 h. Using MANOVA with Wilks-Lamda correction, a significant overall Treatment (LPS vs. Saline) · Time was detected, F = 5.81, p = .031. Regional brain [F]FDG uptake was significantly higher in 7 or 8 regions in the 2 h LPS group (n = 7) vs. saline control (n = 6). In the 6 h LPS group (n = 8), no significant differences were observed vs. controls (n = 7). At 2 h, the most robust metabolic increase were in the temporal cortex (36%, p = .009), hippocampus (32%, p = .017) and thalamus (30%, p = .015). In study 2, using MANOVA with Wilks-Lamda correction, a significant overall Drug (LPS vs. Saline) · Dose (5, 50, 100 lg/kg of LPS) was detected, F = 7.82, p < .01. A linear increase in cortical regions of interest activity appreciated in all areas tested. Conclusions: This study demonstrates that a peripheral immune challenge activates a cortical–subcortical circuit that may share a common neural substrate with affective disorders (e.g., Major Depression) and perhaps other neurological diseases (e.g., Alzheimer s Disease, Parkinson s Disease). Critical importance is confirming the anatomic specificity of immune effects in the CNS, identifying the neural circuits involved in immune-to-brain interactions, the nature of these interactions in specific areas, and their time courses. Through functional brain activity models of infection like this one we may gain insight into novel treatment options for some difficult-to-treat illnesses.

99 Immunization with KLH differentially affects splenic sympathetic activity in two strains of young and old rats

analysis of covariance, the preto post-intervention comparisons indicated that at post-intervention, those in the Tai Chi group had higher existential well-being (p 6 .01), higher perceptions of social support in the realm of guidance (p 6 .05), and more frequently used appraisal-focused coping strategies (p 6 .05). Immunological differences for the Tai Chi group included lower levels of TNF-a (p 6 .01) and higher levels of IL-2 (p 6 .05). Tai Chi practice entails several potentially therapeutic aspects. Learning to experience the world from a mindful, balanced perspective as well as exploring stress responses through meaningful meditative movement encourages proactive rather than reactive responses to perceived stress. Perhaps most importantly, altering perceptions of stressors and strengthening existential well-being along with the sense of available social support may be key components in ultimately impacting neuroendocrine-immune processes and health outcomes. Elevated levels of IL-2 may be associated with reduced physiological stress effects and enhanced cellular immunity overall, whereas reduction in levels of TNF-a may be related to decreased stimulation of the HPA axis and lowered induction of illness behaviors such as fatigue and depressed mood. Further examination of immune parameters will be needed to explain changes in cytokine patterns. However, it is possible that enhanced well-being and altered perceptions of stressors associated with Tai Chi training are causally related to such changes, as would be predicted in the psychoneuroimmunological framework.