Changes in cognitive coping skills and social support during cognitive behavioral stress management intervention and distress outcomes in symptomatic human immunodeficiency virus (HIV)-seropositive gay men

OBJECTIVE

We have previously reported decreases in dysphoria, anxiety, and total mood disturbance in symptomatic HIV seropositive gay men after a 10-week cognitive behavioral stress management (CBSM) group intervention. This structured intervention was designed a) to increase cognitive and behavioral coping skills related to managing the distress of symptomatic HIV, and b) to increase social support among group members. Here we examine the relative contribution of changes in coping skills and social support during the intervention period to reductions in dysphoria, anxiety, and distress-related symptoms in this sample.

METHODS

Participants were randomized to a 10-week CBSM group intervention or to a wait-list control condition. Coping, social supports, and mood were measured before and after the intervention period.

RESULTS

Members of the CBSM group (N = 22) showed significant improvement in cognitive coping strategies involving positive reframing and acceptance, and in social supports involving attachment, alliances, and guidance at the end of the 10-week CBSM program compared with controls (N = 18) who showed decrements in these coping abilities and no changes in social support. Improved cognitive coping, specifically acceptance of the HIV infection, was strongly related to lower dysphoria, anxiety, and total mood disturbance in both conditions. Changes in social support and in cognitive coping skills seem to mediate the effects of the experimental condition on the changes in distress noted during the intervention.

CONCLUSIONS

These results suggest that cognitive coping and social support factors can be modified by psychosocial interventions and may be important determinants of the changes in psychological well-being and quality of life during symptomatic HIV infection that can be achieved through this form of intervention.

Measurement of perceived disruption during rebuilding following Hurricane Andrew

The purpose of this study was to develop and evaluate a measure of perceived disruption during rebuilding following a disaster. Two eight-item scales, which measured intensity of disruption during the entire repair phase (Intensity-RP) and intensity of disruption during the past month (Intensity-PM) were developed and administered to 135 survivors of Hurricane Andrew. At 9 to 12 months postdisaster, Intensity-RP and Intensity-PM were both significantly associated with scores on the Global Severity Index of the SCL-90-R, and with scores on the Impact of Event-Intrusion Scale; Intensity-PM alone was significantly associated with PTSD scores. Regression analyses indicated that each scale contributed significant unique variance in predicting mental health symptoms, even after controlling for relevant demographic and initial disaster exposure variables.

Functional relationship between the hypothalamic vigilance area and PAG vigilance area

The vigilance reaction is characterized by a large bradycardia, a pressor response, and inspiratory apnea in anesthetized rabbits and the inhibition of movement in conscious rabbits. This affective response pattern can be elicited by electrical stimulation of the dorsolateral hypothalamus (the hypothalamic vigilance area) or the ventrolateral periaqueductal gray (the periaqueductal gray vigilance area). The present study sought to advance our understanding of the functional relationship between the hypothalamic vigilance area (HVA) and the periaqueductal gray vigilance area (PVA) by measuring the effects of transverse transections of the caudal portion of the ventrolateral PAG (vlPAG) upon the cardiovascular responses elicited from the dorsolateral hypothalamus and the rostral vlPAG. Selective transverse transections of the caudal vlPAG significantly reduced the magnitudes of the bradycardia and pressor response elicited by stimulation of the PVA rostral to the transection site, but had minimal impact on the cardiovascular responses evoked by stimulation of the HVA. These findings suggest that the cardiovascular responses elicited by stimulation of the vlPAG are mediated by a neural pathway that is parallel, at least in part, to the one that subserves the response elicited from the HVA. The results also provide support for the view that the PAG is not an essential structure in the mediation of the autonomic components of affective behaviors involving behavioral inhibition.

Influence of ethnicity and gender on cardiovascular responses to active coping and inhibitory-passive coping challenges

OBJECTIVE

The goal of this study was to evaluate how black and white men and women responded physiologically to specific laboratory challenges.

METHODS

Hemodynamic responses to an active coping (evaluated speaking) and two inhibitory-passive coping (mirror tracing, cold pressor) tasks were examined in 138 black and white men and women.

RESULTS

Significant ethnicity by gender interactions occurred for the evaluated speaking task. Black men responded with lower blood pressure, cardiac output or heart rate, or both, than black women, white men, and white women, who did not differ from each other. Black men, relative to the other subgroups, also reported more inhibitory-passive coping, hostility, and pessimism, and less social support. Whites also responded with greater increases in systolic blood pressure during mirror tracing than blacks.

CONCLUSIONS

These findings indicate that black-white differences in physiological responsivity obtained for men may have limited generalizability for women. The results also suggest that environmental and social factors rather than genetic or constitutional factors may play a role in black-white reactivity differences.

Directive and nondirective social support in diabetes management

Directive and Nondirective Support were distinguished (interrater agreement = 88.2%) through open-ended interviews completed by 60 adults with Insulin Dependent Diabetes Mellitus. Supporting validity, the sum of both Directive and Nondirective Support was correlated with scores on the Interpersonal Support Evaluation List (ISEL; r = .36). Supporting their distinction, Directive and Nondirective Support were inversely correlated (r = -.26), and Directive but not Nondirective Support decreased with age. Partial/correlations controlled for general support as measured by the ISEL, to examine the unique associations of Directive and Nondirective Support. For those less than 30 years old, Nondirective Support was associated with better metabolic control (p = .004). For those 30 or older, Directive Support appeared counterproductive, being associated with greater negative mood (p = .02). Different types of support may play different roles in different areas of disease management (e.g., metabolic control versus mood) and as a function of individual characteristics such as age.

Coping self-efficacy buffers psychological and physiological disturbances in HIV-infected men following a natural disaster

The importance of coping self-efficacy (CSE) appraisals on psychological and physiological functioning for HIV seropositive patients facing a severe environmental stressor was tested comparing 37 HIV-infected gay men and 42 healthy male control participants following Hurricane Andrew. Results suggested that greater levels of CSE were related to lower emotional distress and posttraumatic stress disorder (PTSD) symptoms in both groups. In addition, greater CSE was associated with lower norepinephrine to cortisol ratios in the HIV group but not in the healthy control group. Results are discussed in relation to the coping process for HIV-infected individuals specifically and chronically ill populations in general who face severe environmental stressors.

Change in CD4+ cell enumeration following aerobic exercise training in HIV-1 disease: possible mechanisms and practical applications

Growing evidence suggests that routine physical activity, by individuals who are HIV-1 infected, may have significant impact on several important components of good health. Some of the physical benefits noted are: an increase in cardiopulmonary fitness, improved muscle function, and weight gain, while psychological benefits consisting of improved mood states and increased active coping behaviors have been observed. However, the emphasis of this paper is on the effects of exercise training on the enumeration of CD4+ cells in HIV/AIDS. A review of all the available literature revealed: (1) no decline in CD+ cell counts seen in any of the studies, regardless of the initial stage of disease, level of CD4+ cells, or symptomatology; (2) a trend toward an increase in the number of CD4+ cells in all but one study, with the more significant increases seen in those subjects at earlier stages of disease; and (3) the importance of homogeneous study samples when investigating the effects of exercise in a dynamic disease, such as HIV/AIDS. With regard to possible mechanisms, psychological stress has been implicated among the cofactors contributing to the immunological decline in HIV-1 disease. Good evidence was presented which supports the stress management role of exercise training as a means to explain the buffering of these suppressive stressor effects, thereby facilitating a return of the CD4+ cell count to more normal levels. We therefore believe that the observed elevation in the number of CD4+ cells actually represents a normalization of CD4+ cells. With regards to practical application, collectively these studies provide reason to encourage HIV-1 infected individuals to begin an exercise training program, preferably while they are in the early stages of disease, and in compliance with the suggested guidelines.

Posttraumatic stress symptoms, intrusive thoughts, loss, and immune function after Hurricane Andrew

OBJECTIVE

To examine the impact of and relationship between exposure to Hurricane Andrew, a severe stressor, posttraumatic stress symptoms and immune measures.

METHODS

Blood draws and questionnaires were taken from community volunteer subjects living in the damaged neighborhoods between 1 and 4 months after the Hurricane.

RESULTS

The sample exhibited high levels of posttraumatic stress symptoms by questionnaire (33% overall; 76% with at least one symptom cluster), and 44% scored in the high impact range on the Impact of Events (IES) scale. A substantial proportion of variance in posttraumatic stress symptoms could be accounted for by four hurricane experience variables (damage, loss, life threat, and injury), with perceived loss being the highest correlate. Of the five immune measures studied Natural Killer Cell Cytotoxicity (NKCC) was the only measure that was meaningfully related (negatively) to both damage and psychological variables (loss, intrusive thoughts, and posttraumatic stress disorder (PTSD). White blood cell counts (WBCs) were significantly positively related with the degree of loss and PTSD experienced. Both NKCC (lower) and WBC were significantly related to retrospective self-reported increase of somatic symptoms after the hurricane. Overall, the community sample was significantly lower in NKCC, CD4 and CD8 number, and higher in NK cell number compared to laboratory controls. Finally, evidence was found for new onset of sleep problems as a mediator of the posttraumatic symptom-NKCC relationship.

CONCLUSIONS

Several immune measures differed from controls after Hurricane Andrew. Negative (intrusive) thoughts and PTSD were related to lower NKCC. Loss was a key correlate of both posttraumatic symptoms and immune (NKCC, WBC) measures.

Psychological stress, exercise and immunity

In terms of cardiovascular, endocrine and immune responses, acute high-intensity aerobic exercise stress may be considered as a subcategory of stressful active coping. The cardiorespiratory responses of both include increases in heart rate, cardiac output, systolic blood pressure, skeletal muscle vasodilation and oxygen consumption. Neurohormonal responses include increases in catecholamines as well as elevations in cortisol under high but relatively low sympathetic activation. Immune system responses include increases in natural killer (NK) cell number and cytotoxicity and suppressor/cytotoxic lymphocytes as well as decreased proliferative response to mitogens. Task and recovery periods for both acute psychological stress or exercise show biphasic changes in immune response such that immune status is negatively impacted during recovery. Chronic life stressors influence acute cardiovascular, endocrine and immune responses to acute stressors. In addition, both chronic stress and unusually heavy chronic exercise can negatively impact immune status. Given impaired immune status following chronic stress and interactive effects of acute and chronic stressors (e.g. blunted acute NK responses to acute stressors), it is suggested that these factors may extend the window of vulnerability for infectious agents to act following acute psychological (e.g. examinations) or strenuous exercise (competitive athletics) stressors.

Cardiorespiratory components of defense reaction elicited from paraventricular nucleus

The present study was conducted to test the hypothesis that the paraventricular nucleus of the hypothalamus (PVN) is involved in the mediation or modulation of the cardiorespiratory components of the defense reaction (DR) in rabbits. Electrical stimulation of the PVN elicited increases in blood pressure and heart rate, hyperventilation, decreased blood flow to the visceral organs, and an increase in blood flow to the hindlimbs that was mediated by an atropine-sensitive vasodilation system. This response pattern is nearly identical to the one that is elicited by electrical stimulation of the hypothalamic defense area. In addition, the cardiomotor component of the baroreceptor reflex was observed to be suppressed during electrical stimulation of the PVN. Previous studies have shown that electrical stimulation of the hypothalamic defense area also leads to inhibition of the cardiomotor component of the baroreceptor reflex. The results of the present study provide evidence that the PVN is involved in the mediation or modulation of the defense reaction.

Cognitive-behavioral stress management decreases dysphoric mood and herpes simplex virus-type 2 antibody titers in symptomatic HIV-seropositive gay men

This study tested the effects of a 10-week group cognitive-behavioral stress management (CBSM) intervention on mood and immunologic parameters in HIV-seropositive gay men whose disease had progressed to a symptomatic stage. Men were randomized to either CBSM or a modified waiting-list control group. The CBSM intervention significantly decreased self-reported dysphoria, anxiety, and total distress. Individuals who practiced relaxation more consistently had significantly greater drops in dysphoria. The intervention also decreased herpes simplex virus-Type 2 (HSV-2) immunoglobulin G antibody titers. The control group showed no significant changes in either mood or antibody titers. Individual difference analyses revealed that decreases in dysphoria significantly predicted lower HSV-2 antibody titers by the end of the 10-week period. Neither group displayed changes in HSV-Type 1 antibody titers or in CD4+ or CD8+ cell numbers.

Behavioral characteristics of defense and vigilance reactions elicited by electrical stimulation of the hypothalamus in rabbits

An automated tracking system was used to assess the behavioral changes elicited by electrical stimulation of the hypothalamic sites that yield the cardiorespiratory components of defense reaction and vigilance reaction in rabbits. Electrical stimulation of the hypothalamic defense area (HDA) at intensities near threshold led to cessation of body movements coupled with head movements suggesting increased attention to the environment. HDA stimulation at higher intensities evoked agitated running and hindlimb thumping; the amount of running was proportional to stimulus intensity. Electrical stimulation of the hypothalamic vigilance area (HVA) at intensities near threshold elicited orienting behaviors that were similar to those elicited by stimulating the HDA at low suprathreshold current intensities. Stimulation of the hypothalamic vigilance area (HVA) at higher intensities elicited phasic immobility, increased extensor muscle tension, and head tremor. The behavioral changes elicited by HDA and HVA stimulation were accompanied by pupil dilation and exophthalmos.

Insulin sensitivity and blood pressure in a biethnic sample: the Miami Community Health Study

An association between blood pressure and insulin sensitivity among normotensive African-Americans has not been demonstrated consistently in epidemiologic studies. Part of the discrepancy may be due to studying persons with profound obesity-an insulin-resistant state itself. The association between insulin-mediated glucose uptake (i.e., insulin sensitivity) and blood pressure was examined among 25 nondiabetic African-American and 28 white non-Hispanic persons aged 25-44 years who ranged from normal weight to obese, using the hyperinsulinemic euglycemic clamp technique. In bivariate analyses, insulin sensitivity was inversely related to systolic (p < 0.01) and diastolic blood pressure (p = 0.08) among African-American persons and to diastolic blood pressure among white non-Hispanic subjects (p < 0.05). Covariate adjustment for age and sex had only a marginal effect on these results. When the data were pooled and further adjusted for ethnicity, insulin sensitivity remained significantly associated with both systolic and diastolic blood pressure (p < 0.01 for each). To consider the effect of obesity, body mass index (BMI) was divided at the sample median (26.5 kg/m2) and the analyses were repeated within each stratum. Among those whose BMI was below the median value, each increment in insulin sensitivity was associated with a 2-mmHg decrease in systolic blood pressure (p = 0.02). These results suggest that ethnicity was not a strong effect modifier in this sample and indicated that insulin sensitivity was inversely related to blood pressure level in these normotensive African-American and white, non-Hispanic participants.

Psychiatric morbidity following Hurricane Andrew

The nature of psychiatric morbidity in previously non-ill subjects from the area most affected by Hurricane Andrew was investigated at 6-12 months posthurricane. Preliminary associations of morbidity with personal and event-related risk factors were also determined. Fifty one percent (31/61) met criteria for a new-onset disorder, including posttraumatic stress disorder (PTSD) in 36%, major depression (MD) in 30%, and other anxiety disorders in 20%. Thirty four subjects (56%) had significant symptoms persisting beyond 6 months. Having sustained "severe damage" was the risk factor most strongly associated with outcome. Our data underscore the range of psychiatric morbidity related to a natural disaster, and suggest a relationship to chronic stressors.

Modulation of the baroreceptor reflex by stimulation of the hypothalamic defense and vigilance areas

Electrical stimulation of the hypothalamic defense area (HDA) elicits a pressor/tachycardia response that is believed to prepare an animal for fight or flight. In contrast, electrical stimulation of the hypothalamic vigilance area (HVA) evokes a pressor/bradycardia response that is associated with the inhibition of movement. The differences in the behavioral components of these two affective response patterns suggest differential modulation of the baroreceptor reflex. The present study tested this idea by assessing the effects of electrical stimulation of the HDA and the HVA upon the bradycardia/depressor response elicited by stimulation of the aortic nerve (AN) in rabbits. Concurrent HDA and AN stimulation was observed to attenuate the AN-elicited bradycardia but enhanced the depressor response elicited by AN stimulation. In contrast, concurrent stimulation of the HVA and AN enhanced the bradycardia elicited by AN stimulation but reduced the magnitude of the AN-elicited depressor response. These results provide evidence for differential modulation of the baroreceptor reflex during the defense and vigilance reactions.

Immunohistochemical expression of the c-Fos protein in the spinal trigeminal nucleus following presentation of a corneal airpuff stimulus

This study examined the expression of the c-Fos protein in the rabbit's central nervous system to determine which areas are activated by the presentation of a corneal airpuff. Previous work has shown that pairing a corneal airpuff unconditioned stimulus (US) with a tone conditioned stimulus (CS) produces reliable heart rate (HR) conditioning. In this study restrained awake rabbits received 100 corneal airpuffs. Brains were then processed immunohistochemically for the c-Fos protein. In animals that received the airpuff the ventral portion of the ipsilateral spinal trigeminal subnucleus caudalis (SVc) and interpolaris (SVi), and the dorsal raphe nucleus exhibited a greater number of c-Fos labeled cells compared to control animals. Another group of animals was given microinjections of WGA-HRP in the medial nucleus of the medial geniculate (mMG) to determine if this critical auditory area of the HR conditioning circuitry receives projections from SVc and SVi. These injections produced retrograde labeling in the same areas of SVc and SVi activated by the airpuff. Thus, a corneal airpuff activates neurons in SVc and SVi which could then activate neurons in mMG. This provides additional evidence that CS and US information converge in mMG.

Changes of synaptic efficacy in the medial geniculate nucleus as a result of auditory classical conditioning

In this study we examined inputs to neurons in the medial subnucleus of the medial geniculate nucleus (mMG) for changes of synaptic efficacy associated with heart-rate conditioning to an auditory conditioned stimulus (CS). Conditioning-related changes of synaptic efficacy were measured in awake animals by examining mMG single-unit responses evoked by stimulation of one of two areas that send auditory CS and nonauditory information monosynaptically to the mMG, the brachium of the inferior colliculus (BlC) and the superior colliculus (SC). Synaptic efficacy was measured before, immediately after, and 1 hr after one session of classical conditioning with a tone CS and a corneal airpuff unconditioned stimulus. To determine whether conditioning produced changes of synaptic efficacy on the auditory BlC inputs to mMG cells and not general changes of cellular excitability, analyses of synaptic efficacy were performed on the mMG units that exhibited short-latency evoked responses (< 3.5 msec) to both BlC and SC stimulation. Analyses revealed that the BlC but not the SC test stimulus-evoked unit activity from the same neurons exhibited the following changes immediately after conditioning: decreases in unit response latency, increases in unit response reliability, and increases in spike frequency. BlC-evoked unit responses after pseudoconditioning did not exhibit these changes in unit responding. These results suggest that the synapses carrying auditory CS information to mMG neurons increase in strength as the result of associative conditioning with an acoustic CS. Some of these changes of synaptic efficacy remained 1 hr after training.

Combined postischemic hypothermia and delayed MK-801 treatment attenuates neurobehavioral deficits associated with transient global ischemia in rats

The present study was designed to determine whether postischemic hypothermia, delayed MK-801 (dizocilpine) administration, or a combination of these treatments can provide lasting neurobehavioral protection following transient global ischemia in rats. Rats were subjected to 10 min of normothermic (37 degrees C) ischemia induced by 2-vessel occlusion and hypotension (50 mmHg) or sham procedures. Ischemia was followed by either: (a) 3 h at normothermic brain temperatures, (b) 3 h of postischemic brain hypothermia at 30 degrees C, (c) hypothermia coupled with MK-801 (4 mg/kg, i.p.) on postischemic days 3, 5 and 7, or (d) postischemic MK-801 treatment alone. Neurobehavioral evaluation 6-8 weeks following surgery showed that normothermic ischemia (NI) was associated with water maze navigational deficits, including performance on a simple place task involving finding a hidden platform maintained in one position for 6 days, and a learning set task in which the platform was moved to a different location each day (both P's < 0.02 vs. sham). NI was also associated with increased locomotion in an open field (P < 0.01 vs. sham). A combination of postischemic hypothermia and delayed MK-801 injections provided partial protection from ischemic-associated hyperactivity in the open field (P < 0.02 vs. NI), and robust protection from simple place task deficits (P < 0.02 vs. NI). Evidence for significant protective effects of MK-801 or hypothermia alone was observed in the learning set, during the final trial blocks each day. These results provide further evidence for neuroprotective effects of these treatments at chronic survival intervals, and indicate that the therapeutic window for attenuating ischemic damage is considerably longer than has heretofore been appreciated.

Hypertension in patients with diabetes mellitus

Diabetes mellitus and hypertension each confer increased cardiovascular risk. That risk is much greater when the diseases coexist and is further magnified by their frequent association with dyslipidemia and central obesity. Insulin resistance appears to be an important common component to these four entities, whether or not the relationship is truly cause and effect. Increased renal tubule absorption of sodium and increased sympathetic nervous system stimulation from insulin have been said to be the mechanisms by which elevated levels of insulin cause hypertension. However, animal experiments suggest that these are short-term effects only and that long-term insulin may actually increase peripheral blood flow and reduce blood pressure. Experiments in humans suggest that the insulin resistant state in obese patients and type II diabetics is associated with a decrease of the usual vasodilatory effect of insulin. Antihypertensive drugs have differing effects on insulin resistance. Angiotensin converting enzyme inhibitors, alpha-adrenergic blockers, and dihydropyridines appear to improve insulin sensitivity. Other calcium channel blockers appear to be neutral, as is furosemide. Thiazide diuretics, spironolactone, and beta-adrenergic blockers impair insulin sensitivity. The drugs that increase insulin sensitivity also tend to improve dyslipidemia or remain lipid neutral. In contrast, those drugs that tend to impair insulin sensitivity also tend to worsen dyslipidemia.

Physical symptoms of chronic fatigue syndrome are exacerbated by the stress of Hurricane Andrew

This study examined the effects of Hurricane Andrew on physical symptoms and functional impairments in a sample of chronic fatigue syndrome (CFS) patients residing in South Florida. In the months after Hurricane Andrew (September 15-December 31, 1992), 49 CFS patients were assessed for psychosocial and physical functioning with questionnaires, interviews, and physical examinations. This sample was made up of 25 CFS patients living in Dade county, a high impact area, and 24 patients in Broward and Palm Beach counties, areas less affected by the hurricane. Based on our model for stress-related effects on CFS, we tested the hypothesis that the patients who had the greatest exposure to this natural disaster would show the greatest exacerbation in CFS symptoms and related impairments in activities of daily living (illness burden). In support of this hypothesis, we found that the Dade county patients showed significant increases in physician-rated clinical relapses and exacerbations in frequency of several categories of self-reported CFS physical symptoms as compared to the Broward/Palm Beach county patients. Illness burden, as measured on the Sickness Impact Profile, also showed a significant increase in the Dade county patients. Although extent of disruption due to the storm was a significant factor in predicting relapse, the patient's posthurricane distress response was the single strongest predictor of the likelihood and severity of relapse and functional impairment. Additionally, optimism and social support were significantly associated with lower illness burden after the hurricane, above and beyond storm-related disruption and distress responses. These findings provide information on the impact of environmental stressors and psychosocial factors in the exacerbation of CFS symptoms.

Simultaneous single unit recording in the medial nucleus of the medial geniculate nucleus and amygdaloid central nucleus throughout habituation, acquisition, and extinction of the rabbit's classically conditioned heart rate

The present study examined single neuron activity in the medial nucleus of the medial geniculate (mMG) and amygdaloid central nucleus (ACe) simultaneously across several phases of differential heart rate conditioning (habituation, acquisition, and extinction). Within the same animals, the magnitude of mMG and ACe unit responses to two tone conditioned stimuli (CS) exhibited habituation, differential acquisition, and extinction. Neurons in each area developed a differential response latency to the CSs during acquisition, suggesting that mMG and ACe may be involved in changes of synaptic efficacy. Units in both areas rapidly developed a differential response magnitude to the CSs (< 6 acquisition trials), however, mMG units responded to the CSs with a shorter latency than ACe units across all phases of training. This suggests that unlearned and learned CS information may access mMG before ACe. These results are consistent with the notion that conditioning-induced plasticity which occurs in mMG may influence the conditioning-induced plasticity that occurs further downstream in the amygdala.

Destruction of neurons in the VPM thalamus prevents rabbit heart rate conditioning

The present study examined the role of the ventral posterior medial nucleus of the thalamus (VPM) in classical heart rate (HR) conditioning using an acoustic conditioned stimulus (CS) and a corneal air puff unconditioned stimulus (US). Previous research suggests that VPM neurons are activated during the presentation of a corneal air puff US. Rabbits were given ibotenic acid lesions in the VPM and subjected to one Pavlovian HR conditioning session. The results of the present study demonstrate that destruction of cell bodies in the VPM reduces HR conditioning to the level of a pseudoconditioning control without affecting HR baseline, or orienting responses to the CS. Lesions of the VPM also significantly augment the tachycardiac unconditioned response, suggesting that VPM lesions alter the somatosensory processing of the US.

Psychosocial counseling to improve quality of life in HIV infection

Psychosocial interventions such as cognitive behavioral stress management (CBSM), may enhance coping and social support which contribute to an improvement of quality of life factors such as emotional functioning, social functioning, and sense of well-being, for HIV-infected men during several phases of HIV spectrum disease. These phases include the acutely stressful period immediately following notification of HIV+ status, the adjustment period following this news, and the process of dealing with chronic symptomatic HIV infection. Normalization of some aspects of immunological status were found to accompany some of these psychosocial changes in the short-run. Longer-term follow-up indicated relationships between psychosocial factors and improved immunological status and physical functioning up to 2 years later. Factors such as an increased use of active coping strategies, including relaxation exercises, use of more functional appraisals and elicitation of social support, and decreased use of denial/avoidance coping strategies, may be key predictors of longer-term emotional well-being, social functioning, and physical functioning in HIV-infected populations. Special issues need to be addressed in emerging models of quality of life assessment in HIV populations. For example, the way resurgence of stigmatization and self-doubt affects sense of identity and well-being need to be addressed in quality of life research as well as in psychosocial interventions. Loss of employment and its financial and existential consequences are also factors which impact sense of self and well-being, and need to be addressed both in research as well as in interventions. The effect of repeated HIV-related bereavements upon an individual's social network and the emotional, social, and physical sequelae of bereavement have implications for HIV quality of life research as well. Quality of survival time has become a paramount issue in the context of HIV spectrum disease. Examining the relationships among coping strategies, social support, emotional well-being, realistic appraisals of one's functioning in comparison to their aspirations, and the influence of psychosocial functioning on disease course are central missions of our research program.

Comparison of peripheral blood flow patterns associated with the defense reaction and the vigilance reaction in rabbits

The present study compared the skeletal muscle and visceral blood flow patterns elicited by electrical stimulation of the hypothalamic defense area (HDA) and the hypothalamic vigilance area (HVA) of the rabbit. Electrical stimulation of the HDA evoked a pressor response, tachycardia, hyperventilation, an increase in blood flow to the skeletal muscles and decreased blood flow to visceral organs. Stimulation of the HVA yielded a pressor response, bradycardia, inspiratory apnea and decreased blood flow to both the skeletal muscles and the viscera. Intravenous injections of atropine methyl nitrate significantly reduced the HVA-elicited bradycardia and the HDA-elicited increase in blood flow to the skeletal muscles, thereby providing evidence that the bradycardia was mediated by vagal efferents and that the rabbit has an atropine-sensitive cholinergic vasodilation system. The decrease of blood flow to the visceral organs associated with the defense reaction and vigilance reaction was reversed by intravenous injections of the alpha-1 receptor blocker prazosin.

Effects of aerobic exercise training on lymphocyte subpopulations

This study was conducted to determine the effects of an aerobic exercise training program on subpopulations of lymphocyte phenotypes. Fourteen healthy but sedentary males, 18-40 years of age, were randomly assigned to either an aerobic exercise training or control condition. Aerobic exercise training consisted of three 45-minute sessions of cycle ergometry exercise per week at 70-80% of age-predicted maximum heart rate for ten weeks. The aerobic exercise training resulted in a significant decrease in submaximal heart rate from 176 to 150 beats per minute to a fixed work rate of 150 watts (p < .01). This training effect was accompanied by increases in the resting level of the following lymphocyte subpopulations: CD2 (1717 vs 2183 mm3; p < .01), CD4 (942 vs 1280 mm3; p < .01), CD45RA+CD4+ (312 vs 595 mm3; p < .01), CD8 (655 vs 816 mm3; p < .05), and CD20 (162 vs 244 mm3; p < .01) cell counts. These findings indicate that several lymphocyte subpopulations are increased following a 10-week program of aerobic exercise training.

Basal and reactive plasma catecholamine levels under stress and anesthesia in rabbits

The present study was undertaken to determine if electrical stimulation of the hypothalamic defense area (HDA) and baroreflex activation elicited by head up body tilt produced changes in plasma catecholamine (CA) levels in anesthetized rabbits. We also compared the effects of two anesthetics, isoflurane and sodium pentobarbital, upon basal and reactive CA levels, and upon autonomic reactivity. HDA stimulation was found to produce significant increases in plasma norepinephrine (NE) levels but not epinephrine (E) levels. Passive tilt was found to produce statistically significant increases in NE levels for both anesthetics used and a significant increase in E levels for animals anesthetized with isoflurane. Basal and reactive measurements provided evidence that pentobarbital has a more suppressive effect upon the autonomic nervous system than isoflurane: (a) Basal NE levels were significantly lower in pentobarbital anesthetized animals than in isoflurane-anesthetized animals; and (b) Baroreceptor sensitivity to a passive tilt stressor was significantly higher for animals anesthetized with isoflurane than for animals anesthetized with pentobarbital.

Emotional disclosure through writing or speaking modulates latent Epstein-Barr virus antibody titers

Healthy Epstein-Barr virus (EBV) seropositive undergraduates (N = 57) completed a personality inventory, provided blood samples, and were randomly assigned to write or talk about stressful events, or to write about trivial events, during three weekly 20-min sessions, after which they provided a final blood sample. Individuals assigned to the verbal/stressful condition had significantly lower EBV antibody titers (suggesting better cellular immune control over the latent virus) after the intervention than those in the written/stressful group, who had significantly lower values than those in the written/trivial control group. Subjects assigned to the written/stressful condition expressed more negative emotional words than the verbal/stressful and control groups and more positive emotional words than the verbal/stressful group at each time point. The verbal/stressful group expressed more negative emotional words compared with the control group at baseline. Content analysis indicated that the verbal/stressful group achieved the greatest improvements in cognitive change, self-esteem, and adaptive coping strategies.

Stimulus dimensions of the cold pressor test and the associated patterns of cardiovascular response

Hemodynamics of the cold pressor response in relation to its pain and nonpain stimulus components were investigated in normotensive college men using the foot and forehead cold pressor tasks. Mechanisms of pain- and non-pain-related increases in blood pressure were analyzed as residual effects of concurrent changes in total peripheral resistance and cardiac output. The identified partial relationships suggested that the response pattern associated with pain included positive change both in cardiac output and in total peripheral resistance, whereas the nonpain-related response was limited to an increase in total peripheral resistance. Analyses of individual differences in cardiovascular responses to pain further indicated that pain-related increments in blood pressure were mediated by a steeper rise in total peripheral resistance, an increase in heart rate, and an apparent increase in preload. At baseline, high reactors to pain manifested relatively elevated total peripheral resistance, diminished cardiac output, and an indication of a reduced inotropic state, suggesting that altered basal homeostasis may discriminate normotensive individuals displaying heightened cardiovascular reactivity to aversive cold stimulation.

Modulation of neuronal firing in the medullary solitary complex by electrical stimulation of the hypothalamic defense and vigilance areas in rabbits

The present study sought to establish functional connections between two regions in the hypothalamus associated with the cardiorespiratory concomitants of affective behavior, and neurons in the dorsal medulla thought to be involved in the mediation of the baroreceptor reflex. Single cell recordings were made in the solitary complex of the medulla (nucleus of the tractus solitarius and dorsal vagus nucleus) of anesthetized rabbits. An attempt was made to modulate the activity of these neurons by electrically stimulating two hypothalamic sites: the hypothalamic defense area (HDA) and the hypothalamic vigilance area (HVA). Responses of solitary complex neurons to a bolus injection of phenylephrine and an injection of physiological saline in a blind sac preparation were assessed in order to test for baroreceptor input. Electrical stimulation of the HDA or the HVA was found to decrease the firing rate of most solitary complex neurons that responded to hypothalamic stimulation. The cells that did show an increase in firing rate were responding to HVA stimulation. Ninety-two percent of the neurons in the solitary complex that responded to HDA or HVA stimulation were also affected by baroreceptor activation. The connections between the HDA, HVA and the solitary complex may account, in part, for the distinctive patterns of cardiorespiratory responses observed when stimulating these two hypothalamic regions.

Emotional disclosure through writing or speaking modulates latent Epstein-Barr virus antibody titers

Healthy Epstein-Barr virus (EBV) seropositive undergraduates (N = 57) completed a personality inventory, provided blood samples, and were randomly assigned to write or talk about stressful events, or to write about trivial events, during three weekly 20-min sessions, after which they provided a final blood sample. Individuals assigned to the verbal/stressful condition had significantly lower EBV antibody titers (suggesting better cellular immune control over the latent virus) after the intervention than those in the written/stressful group, who had significantly lower values than those in the written/trivial control group. Subjects assigned to the written/stressful condition expressed more negative emotional words than the verbal/stressful and control groups and more positive emotional words than the verbal/stressful group at each time point. The verbal/stressful group expressed more negative emotional words compared with the control group at baseline. Content analysis indicated that the verbal/stressful group achieved the greatest improvements in cognitive change, self-esteem, and adaptive coping strategies.

Exercise and psychoneuroimmunology

Psychoneuroimmunology is the study of the interrelationships among psychological, neuroendocrine, and immunological parameters and is concerned with how these relationships may affect an individual's health. Substantial evidence indicates that exercise is associated with improvements in mental health, neuroendocrine, and immune functioning. We synthesize these effects of exercise and propose an "exercise and psychoneuroimmunology" model by which exercise may benefit the psychologic and immunologic sequelae of several chronic diseases. For the past several years we have been investigating exercise training interventions, based on our model, for individuals infected with the human immunodeficiency virus type 1 (HIV-1). These studies indicate that a moderate exercise training program may attenuate the adverse stressor-induced psychologic and immunologic changes for asymptomatic HIV-1 seropositive individuals. In addition, our research indicates that continued aerobic exercise training may result in increased CD4 cell counts, immune surveillance, and a potential for a slowing of disease progression. Other researchers have demonstrated similar beneficial effects of exercise for individuals infected with HIV-1 who are at more advanced stages of disease. Exercise within the context of psychoneuroimmunology appears to be a very promising approach to the treatment of illness and promotion of health.

Recovery of sensorimotor function after distal middle cerebral artery photothrombotic occlusion in rats

BACKGROUND AND PURPOSE

The purpose of the present study was to delineate the behavioral correlates of focal thrombotic occlusion of the distal middle cerebral artery in rats and to compare the pattern of deficits and subsequent recovery to that following proximal middle cerebral artery occlusion.

METHODS

Ten Sprague-Dawley rats underwent photothrombotic occlusion of the distal middle cerebral artery with tandem occlusion of the common carotid arteries (dMCAO group); 10 animals served as operated controls. Beginning on postischemia day 2, animals were given a battery of five tests that assessed sensorimotor integration, attentional mechanisms, and muscle strength; testing continued twice weekly until day 30. Nine days of cognitive testing on the learning set of the water maze task were then given. Infarct volume and hemispheric atrophy were determined for each dMCAO animal.

RESULTS

After ischemia, the dMCAO group exhibited significant behavioral deficits in posture reflex, ability to place a forelimb to various stimuli, limb adduction during rearing, and neglect of contralateral space. These deficits showed variable recovery rates. No deficits were observed in muscle strength or cognitive performance. The deficits and patterns of recovery were related to infarct location and to degree of hemisphere atrophy.

CONCLUSIONS

The present study suggests that a battery of tests is necessary to fully characterize the pattern of behavioral deficits after focal cerebral ischemia. Location of infarct damage and associated degree of hemispheric atrophy were important variables in determining behavioral outcome. The present results are compared with those of the more traditional model of electrocoagulation of the proximal middle cerebral artery.

Changes in cognitive coping strategies predict EBV-antibody titre change following a stressor disclosure induction

Previous research has shown that emotional disclosure of traumatic or stressful events is associated with facilitating insight into the experience, improving mood, and modulating some aspects of the immune system. The current study examined how cognitive changes and experiential involvement during an emotional disclosure induction protocol relate to immune functioning, as measured by IgG antibody titres to the Epstein-Barr virus viral capsid antigen (EBV-VCA). Seventy-six college undergraduates were randomly assigned to either a disclosure induction or an assessment-only control condition. Experimental subjects met with an experimenter for three weekly 20-min individual sessions during which time they were asked to discuss a stressful or traumatic topic which they had previously discussed only minimally with others. Blood was drawn a week prior to the first session and at one week following the third session. Subjects completed the Impact of Event Scale (IES) after session 1 and at followup, and the extent of experiential involvement in disclosure during each session was assessed by means of the Experiencing Scale. Mood was assessed before and after each disclosure using the Nowlis Mood Adjective Checklist. Although the disclosure induction did not directly affect EBV-VCA antibody titres, individual differences in subjects' ability to involve themselves in the disclosure process and abandon their avoidance of the stressful tropic during the course of the 3-wk period were predictive of antibody decrements. These associations were more pronounced for individuals who disclosed older and more troublesome events.

Electrolytic and ibotenic acid lesions of the medial subnucleus of the medial geniculate prevent the acquisition of classically conditioned heart rate to a single acoustic stimulus in rabbits

The present study examined the role of the medial subnucleus of the medial geniculate (mMG) in classical heart rate (HR) conditioning to a single acoustic conditioned stimulus (CS) in rabbits. Previous electrophysiological and neuroanatomical studies have implicated the mMG as a potential site of plasticity in forming the HR conditioned response (CR) to acoustic stimuli. In addition, several studies have found that bilateral lesions of the rabbit mMG prevent differential conditioning to acoustic stimuli, however animals still exhibit a significant bradycardiac response to the tones. In order to determine if the residual bradycardia seen in differential conditioning studies was due to learned responses or non-associative effects, rabbits with either bilateral electrolytic or ibotenic acid lesions of mMG, and animals with lesions outside of mMG (lesion control), were subjected to one session of single tone Pavlovian conditioning. In this paradigm, an acoustic CS was paired with an aversive unconditioned stimulus (US) in the conditioning groups, and in a pseudoconditioning group the CS and US were unpaired. The results suggest that bilateral lesions of mMG prevent the acquisition of the HR CR relative to control lesioned animals. The results also suggest that cells intrinsic to mMG are involved in conditioned bradycardia to a single tone, as well as in the discrimination between two tones, as reported previously. The lesion effects upon CRs are discussed with respect to other areas in the acoustic thalamus.

Differential patterns of dynamic cardiovascular regulation as a function of task

In cardiovascular reactivity studies, interpretations of the processes supporting the blood pressure response may become problematic when systolic blood pressure, diastolic blood pressure, and heart rate all increase in response to a behavioral challenge. Therefore, in addition to evaluating these cardiovascular responses, this study examined cardiac output, total peripheral resistance and systolic time intervals derived from impedance cardiogram, electrocardiogram and phonocardiogram recordings during a speech stressor, a mirror tracing task, and a foot cold pressor test. All of the behavioral stressors elicited increases in blood pressure and heart rate, with the largest changes occurring during the overt speech. Based on the examination of the response patterns of the underlying hemodynamic variables it would appear that, in both men and women, the blood pressure increase during the speech preparation period was supported by increased cardiac output; the speech itself resulted in a mixed pattern of increased cardiac output and total peripheral resistance; whereas, the mirror tracing and cold pressor tasks produced increased total peripheral resistance. Although men and women produced similar response patterns to the behavioral challenges, sex differences in the estimates of myocardial contractility were observed during rest. These results provide evidence that different behavioral stressors can produce a distinct yet integrated pattern of responses, whose differences may be revealed, when impedance cardiography is used, to derive sufficient response measures for assessing dynamic cardiovascular processes.

Signal fidelity requirements for deriving impedance cardiographic measures of cardiac function over a broad heart rate range

Our findings indicate that the impedance cardiogram spectrum extends from DC to 50 Hz. Any amplifier with an upper band limit less than 50 Hz can be expected to produce attenuation and distortion of the impedance cardiogram. This signal attenuation may be systematically enhanced under conditions of high heart rate when a greater proportion of signal energy will be in the upper frequency range of the impedance cardiogram spectrum. Therefore, the present study was designed to assess the influence of amplifier bandwidth on dZ/dtmax, stroke volume, and systolic time intervals (LVET, PEP, QZ, QX). Simultaneously measured delta Z and dZ/dt signals from two impedance cardiographs, with corner frequencies of 120 and 60 Hz for the delta Z and 50 and 15 Hz for dZ/dt channels, were contrasted over a broad range of heart rate (70-150 bpm). In addition to the analog dZ/dt signals obtained from the instruments, the delta Z signals were digitally converted to dZ/dt by off-line digital differentiation with a 50 Hz corner frequency. The results demonstrated that the measurements with the 15 Hz corner frequency, when compared with the 50 Hz corner frequency measurements, systematically attenuated the dZ/dtmax amplitude and stroke volume measurements as heart rate increased. The attenuation of dZ/dtmax and stroke volume ranged from about 13% to 26% as heart rate increased from 70 to 150 bpm. When the upper bandlimit was 50 Hz, the dZ/dt signal had greater resolution of waveform events and produced less prolonged systolic time intervals. The 15 Hz amplifier differentially influenced the B point, Z-peak and X minimum, having no apparent effect on the temporal location of the B point, but delaying the Z-peak about 21.7 ms and the X minimum about 7.4 ms. These findings indicate that impedance cardiographs with insufficient upper bandlimits will differentially influence ICG-derived measurements as heart rate varies.

Defensiveness, trait anxiety, and Epstein-Barr viral capsid antigen antibody titers in healthy college students

The relationship of individual differences in repressive coping styles with differences in antibody titer to Epstein-Barr viral capsid antigen (EBV-VCA) were investigated in a normal, healthy college population made up of people previously exposed to EBV. Each of 54 1st-year undergraduates completed a battery of physical-status questions and items pertaining to potential behavioral immunomodulatory confounds, along with the Taylor Manifest Anxiety Scale (T-MAS) and the Marlowe-Crowne Social Desirability Scale (MC-SDS). Ss reporting high and middle levels of anxiety had higher antibody titers to EBV, suggesting poorer immune control over the latent virus, as compared with the low-anxious group. Similarly, high-defensive Ss had higher antibody titers than their low-defensive counterparts, and neither group differed from the middle group.

The cold pressor test: vascular and myocardial response patterns and their stability

The purposes of the present study were to compare the cardiovascular response patterns evoked by three versions of the cold pressor test (either forehead stimulation or hand or foot immersion) and to determine the reproducibility of the responses over a 2-week interval. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, and systolic time intervals were obtained during rest and during the cold pressor test in 42 young men. Across conditions, the pressor response was supported by peripheral resistance increases with concomitant stroke volume decreases. Although the response patterns were generally similar across sites, exceptions were apparent for heart rate. Forehead stimulation was characterized by no significant change in heart rate, whereas limb (hand or foot) immersion was associated with significant heart rate acceleration. The responses elicited by the three cold pressor test conditions were reliable and showed little evidence of attenuation over the test-retest interval.

The stability of cardiovascular parameters under different behavioral challenges: one-year follow-up

The stability of myocardial, peripheral vascular and systolic time-interval measures was assessed over a one-year period in a sample of ten healthy normotensive men. Subjects participated in three laboratory sessions, the first two of which were two weeks apart, and the third approximately one year later. Measures were sampled during the preparation and delivery of a speech, a mirror star tracing task, and the forehead cold pressor test. The results of intraclass correlations computed between the mean of the first two sessions and the third showed that baseline and task levels were highly reproducible across all tasks and most parameters over the one year interval. Results also showed that the long term stability of delta is largely task-dependent.

Defensiveness, trait anxiety, and Epstein-Barr viral capsid antigen antibody titers in healthy college students

The relationship of individual differences in repressive coping styles with differences in antibody titer to Epstein-Barr viral capsid antigen (EBV-VCA) were investigated in a normal, healthy college population made up of people previously exposed to EBV. Each of 54 1st-year undergraduates completed a battery of physical-status questions and items pertaining to potential behavioral immunomodulatory confounds, along with the Taylor Manifest Anxiety Scale (T-MAS) and the Marlowe-Crowne Social Desirability Scale (MC-SDS). Ss reporting high and middle levels of anxiety had higher antibody titers to EBV, suggesting poorer immune control over the latent virus, as compared with the low-anxious group. Similarly, high-defensive Ss had higher antibody titers than their low-defensive counterparts, and neither group differed from the middle group.

Patterns and stability of cardiovascular responses to variations of the cold pressor test

Test-retest reliabilities and patterns of heart rate and blood pressure responses were examined using variations in the cold pressor test in 113 normotensive white college men. Comparisons were made of stimulus site (forehead vs. foot) and bodily posture (seated vs. supine) across four separate groups of men. The stability of cardiovascular responses was examined over a 2-week-test-retest interval. Different cardiovascular response patterns emerged as a function of stimulation site and posture. Systolic and diastolic blood pressure increases were accompanied by bradycardia in the forehead cold pressor task but by tachycardia in the foot cold pressor task. Systolic blood pressure increases were larger for foot than for forehead stimulation. Heart rate increases were larger for supine than for seated men. Effects on response were independent of postural differences at baseline, and there were no stimulation site by posture interactions. The cardiovascular responses to stimulation did not attenuate across sessions in any experimental condition but were more reliable for foot than for forehead stimulation and for supine than for seated posture. Short-term stability for changes to the task approached that for baseline and task and was higher than has been reported elsewhere.

Ethnicity and ambulatory blood pressure measurement: relationship to clinic and laboratory measurements

African Americans have a higher prevalence of hypertension than white Americans. Morbid consequences of hypertensive disease are greater in blacks than whites. For members of high-risk groups such as blacks, ambulatory blood pressure monitoring may be useful in supplementing casual clinic measurements to prevent misdiagnosis, better characterize the temporal topography of blood pressure responses, and improve prediction of left ventricular hypertrophy, hypertensive complications, morbidity, and mortality. In conjunction with other data, laboratory experiments showing that African Americans as a group show greater peripheral resistance and slowed natriuretic responses to behavioral stressors than whites, appear to provide insights as to why blacks generally respond better to diuretics and calcium channel blockers than to beta-adrenergic antagonists or angiotensin-converting enzyme inhibitors. It is suggested that ambulatory blood pressure monitoring and behavioral tasks in the laboratory may help predict individual responsiveness to antihypertensive agents.

Myocardial and peripheral vascular responses to behavioral challenges and their stability in black and white Americans

The purpose of this study was to assess the short term stability of myocardial and peripheral vascular responses to behavioral challenges, and to compare the response patterns of Black and White men. Blood pressure and heart rate, as well as stroke volume, cardiac output, total peripheral resistance, and systolic time interval measures derived from the impedance cardiogram were obtained in 12 Black and 12 White men. These measures were taken prior to and during an evaluative speech stressor, a mirror star tracing task, and a forehead cold pressor test presented during two laboratory sessions scheduled two weeks apart. In general, total peripheral resistance and impedance-derived baseline measures showed acceptable reproducibility (G greater than .85). With a few exceptions, adequate reliability was also demonstrated for change (delta) scores. All tasks raised blood pressure responses above resting levels. Blacks demonstrated significantly greater increases in total peripheral resistance responses across tasks. Whites but not Blacks also revealed increases above baseline in cardiac output and contractility as estimated by the Heather Index. These findings are consistent with the view that Blacks show greater vascular responsiveness than Whites across a variety of tasks, but reveal less myocardial responsiveness.

Effectiveness of antihypertensive medications in office and ambulatory settings: a placebo-controlled comparison of atenolol, metoprolol, chlorthalidone, verapamil, and an atenolol-chlorthalidone combination

In a double-blind, crossover study, five white men with mild-to-moderate hypertension received placebo and fixed doses of atenolol, metoprolol, chlorthalidone, verapamil, and the combination of atenolol and chlorthalidone in a quasi-random order. Daily dosages were: atenolol, 100 mg; metoprolol, 200 mg; chlorthalidone, 50 mg; verapamil, 240 mg; and the same doses of atenolol and chlorthalidone in combination. Standard office and daytime ambulatory blood pressures were assessed at the end of each month-long trial. Atenolol, metoprolol, chlorthalidone, and verapamil controlled office blood pressure with similar reductions. Verapamil did not lower ambulatory blood pressure at this dose (which is lower than is now commonly used), but reductions in ambulatory blood pressure were similar for atenolol, metoprolol, and chlorthalidone. The combination of atenolol and chlorthalidone maintained blood pressure control more effectively than the single drug treatments in both office and ambulatory settings, and the combined hypotensive effects were additive. However, reductions in the office due to the combination appeared to overestimate hypotensive effectiveness in the ambulatory setting. This study suggests that the effectiveness of commonly prescribed antihypertensive regimens varies according to setting as well as drug, and that assessment of treatment effectiveness can be improved by automated ambulatory blood pressure monitoring.

Ibotenic acid lesions in the amygdaloid central nucleus but not in the lateral subthalamic area prevent the acquisition of differential Pavlovian conditioning of bradycardia in rabbits

The present study examined the effect of ibotenic acid lesions in the amygdaloid central nucleus (ACe) or in the lateral zona incerta of the subthalamus (LZI) on the acquisition of differential Pavlovian conditioning of bradycardia in rabbits. Previous work has shown that bilateral electrolytic lesions in either ACe or LZI abolished the retention of conditioned heart rate (HR) responses. In order to determine whether these findings were due to destruction of cells intrinsic to ACe or LZI, ibotenic acid lesions were placed bilaterally in either structure or in control sites. Following recovery, animals were subjected to differential Pavlovian conditioning in which one tone (CS+) was paired with periorbital shock and a second tone (CS-) was presented alone. It was found that destruction of cell bodies in ACe, but not LZI, prevented the acquisition of the differential bradycardiac conditioned response. In addition, ACe lesions did not interfere with baseline HR, the HR orienting response, the HR unconditioned response to shock, or the concomitantly conditioned corneoretinal potential. The results of this study suggest that destruction of cells intrinsic to ACe selectively prevents the acquisition of differentially conditioned HR, and perhaps other conditioned responses related to conditioned arousal, but does not affect unlearned HR responses or specific somatomotor conditioned responses.

Protective effects of brain hypothermia on behavior and histopathology following global cerebral ischemia in rats

The present experiments were designed to assess whether brain hypothermia can reduce the behavioral and histopathological deficits associated with global forebrain ischemia. Animals were subjected to 12.5 min of four vessel occlusion (4VO) with moderate hypotension, and brain temperature maintained at either 37 degrees C (4VO-37) or 30 degrees C (4VO-30). Behavioral tests designed to assess forelimb reflexes and sensorimotor function were given on post-operative weeks 2 and 4. Beginning in week 5, the rats were trained on a variety of navigation problems in the Morris water maze. Histopathological examination of the tissue 2 months following reperfusion revealed that 4VO-37 animals sustained substantial cell death in hippocampal region CA1 and moderate damage to the dorsolateral neostriatum. 4VO-30 animals showed minimal cell death in CA1 and neostriatum. There were no group differences for any of the sensorimotor measures, or for acquisition performance on either the simple place task or visible platform version of the water maze. In contrast, during acquisition of the learning set task, the performance of 4VO-37 animals was impaired relative to either of the other groups, whereas the performance of 4VO-30 animals was not significantly different from the sham controls. These data suggest that moderate intra-ischemic brain hypothermia provides long-lasting protection from behavioral deficits as well as neuronal injury following transient global ischemia.