David E. Mills

CARDIOVASCULAR CHANGES DURING INDUCED EMOTION: AN APPLICATION OF LANG'S THEORY OF EMOTIONAL IMAGERY

Studies of emotion have provided occasional support for physiological differentiation of affective states; however, the evidence has been inconsistent. The aims of the present study were to investigate cardiovascular changes associated with relived experiences of happiness, sadness, anger, fear, and disgust and to examine the utility of methods designed to optimize the induction of emotional responses. Thirty-four undergraduates who scored 0.5 sd above the mean on Larsen and Dieners Affect Intensity Measure described their most intense experiences of five emotions. These descriptions were then used to induce those emotions while blood pressure and other hemodynamic measures were monitored. Systolic blood pressure, diastolic blood pressure, and stroke volume differentiated among emotions. The results support the suggestion that cardiovascular activity differentiates emotional states and provide some insight into the physiological adjustments subserving such effects. The study demonstrates a method that may be applied to studies of discrete emotions.

Dietary N-6 and N-3 fatty acids and salt-induced hypertension in the borderline hypertensive rat.

This study examined the effects of salt-loading on blood pressure (BP) development in the borderline hypertensive rat (BHR) and its modification by dietary n−3 and n−6 fatty acids. In experiment 1, 4 groups (n=10/group) of male BHR receiving 1% NaCl as a replacement for tap water were placed on chow enriched with either olive oil (OL), sunflower oil (SUN), evening primrose oil (EPO) or fish oil for 6 weeks. BP, heart rate, body weight, water, Na+ and K+ intake and urinary output were measured weekly. SUN and fish oil reduced the pressor response to salt seen vs the OL group by 50%, and EPO abolished the pressor response, reducing BP below control levels. The BP response was unrelated to either food intake or water and electrolyte intake and excretion. In experiment 2, male BHR received water +/− 18∶3n−6 (0.04 mg/hr in OL via ip pump) or 1% NaCl +/− 18∶3n−6 (n=12/group) for 12 weeks, followed by 2 weeks recovery on tap water. Salt increased BP, and 18∶3n−6 decreased this response, but had no effect on animals receiving tap water. In experiment 3, effects of 3 doses of 18∶3n−6 (0.04, 0.08, and 0.12 mg/hr) on the pressor response to 1% NaCl were examined. All doses reduced the BP response to salt vs controls with no dose-response. These data suggest that the BHR is genetically salt-sensitive, and that dietary n−3 and n−6 fatty acids can attenuate the cardiovascular response to salt in this model.

EFFECTS OF PRENATAL AND EARLY POSTNATAL FATTY ACID SUPPLEMENTATION ON BEHAVIOR

Abstract This study examined the effects of n-6 and n-3 fatty acid supplementation, during gestation and nursing, on offspring behavior and learning. Female Wistar Kyoto rats (n=6/group) received 8 week osmotic pumps releasing olive oil (OL), or OL plus linoleic acid, gamma linolenic acid, arachidonic acid, or alpha linolenic acid (0.04 mg/hr). A sixth group received dummy pumps. Animals were then bred. On day 2 postpartum, 3 females/group had pumps removed; the rest underwent sham surgery. Offspring were weaned and placed on normal diets on day 24. Offspring activity was evaluated in the open field on days 26 and 60. Two pups/litter were sacrificed on days 2 and 26 postpartum for brain lipid analysis. Animals underwent active avoidance conditioning between days 63–80 postpartum. Dietary interventions significantly affected locomotor activity on both test days. On day 60, all n-3 and n-6 fatty acids reduced the number of locomotor efforts, while n-6 fatty acids reduced total squares crossed. OL reduced rearing on both test days. Pre-vs. pre-plus-postnatal supplementation produced similar results. The proportion of animals successfully completing the conditioning paradigm was significantly increased by alpha linolenic supplementation. Supplementation produced no changes in brain phospholipids. Open field behavior and learning were unrelated to brain phosphatidylethanolamine levels of 22:6n-3. These data suggest that dietary composition of n-3, n-6, and n-9 fatty acids during development may produce long term changes in behavior and learning ability. These changes occur in the absence of demonstrable alterations of brain membrane lipid composition, and may be due to changes in prostanoid levels and brain growth during development.

Comparison of hemodynamic responses to social and nonsocial stress: evaluation of an anger interview.

Hemodynamic responses to an anger interview and cognitive and physical stressors were compared, and the stability of associated hemodynamic reactions examined. Participants experienced control, handgrip, counting, and mental arithmetic tests and an anger interview on two occasions. Systolic and diastolic blood pressure, heart rate, stroke volume, and cardiac output were measured. Total peripheral resistance was also derived. The anger interview produced larger, more sustained changes in blood pressure in both sessions than the other stressors. These changes were largely a consequence of increased peripheral resistance. Consistent with previous findings, handgrip was associated with a resistance-type reaction whereas arithmetic was associated with a cardiac output-type reaction. There was low-to-modest stability of hemodynamic reactions to the interview. Further research is necessary to optimize its utility in studies of cardiovascular function. Nevertheless, the findings underscore the ability of ecologically relevant stressors to provoke unique configurations of cardiovascular activity.

Effects of acute exercise on cardiovascular reactivity.

Although exercise may modulate cardiovascular reactivity to stress, its acute effects have not been studied extensively. The purpose of this study was to examine over time the acute effects of different durations of aerobic exercise on cardiovascular reactivity to stressors. Twenty-four sedentary men underwent minimal exercise, 1 or 2 hr of stationary cycling at 55% VO2maxHeart rate, blood pressure, and blood catecholamines were measured during cold pressor, Stroop, and public speech tasks 1, 3, and 24 hr after exercise. One or two hours of exercise attenuated blood pressure responses to stress. The attenuation was evident 3 hr following exercise and was most apparent on the cold pressor task. These effects were independent of epinephrine level and stress appraisal. The role of central sympathetic processes in the effects of exercise and methodologic implications are discussed.

Effects of dietary fatty-acid supplementation on fatty-acid composition and deformability of young and old erythrocytes

The effects of cell age on erythrocyte phospholipid fatty-acid composition and deformability were examined in 20 healthy adults (11 male, 9 female) prior to and following 12 weeks of dietary supplementation with 3.5 g/day of safflower oil (high in n - 6 fatty acids) or fish oil (high in n - 3 fatty acids). In the absence of dietary supplementation, old erythrocytes demonstrated an increase in filtration time (P < 0.001), an increase in membrane phospholipid total n - 6 fatty acids (P < 0.01), and a decrease in total n - 3/total n - 6 ratio (P < 0.01) compared to young erythrocytes. Both safflower and fish oil supplementation attenuated age-related differences in membrane phospholipid total n - 6 and total n - 3 fatty acids. Fish oil supplementation also increased the proportion of n - 3 fatty acids (P < 0.01) and the n - 3/n - 6 ratio (P < 0.05) in the phospholipids of both young and old erythrocytes, and eliminated age-related differences in erythrocyte filtration time by reducing the relative filtration time of the old erythrocytes.

Effects of essential fatty acid administration on cardiovascular responses to stress in the rat

This study examined the effects of 18∶2(n−6), 18∶3(n−6), 20∶4(n−6) and 18∶3(n−3) on cardiovascular responses to isolation stress in male rats. Group-acclimated rats were fasted for 2 days, then placed on a fat-free diet. Two wk later animals were divided into six groups (six animals per group) and given eight-wk intraperitoneal osmotic pumps releasing 1.47×10−7 mol/hr of either olive oil (OL), or of 18∶2(n−6), 18∶3(n−6), 20∶4(n−6) or 18∶3(n−3) in OL. Another group received dummy pumps. Two wk after pump implantation, animals were isolated for four wk. Blood pressure (BP), heart rate and body weight were followed before and during stress. Following the stress period, animals were assessed for cardiovascular reactivity to norepinephrine (NOR) and angiotensin (ANG).Prior to isolation, 18∶3(n−6) lowered BP vs OL (p<0.01). Stress increased BP within 24 hr in all groups except 18∶3(n−6) and 20∶4(n−6). Treatment with 20∶4(n−6) vs OL prevented the BP rise (p<0.001) only for the first two wk of stress. Administration of 18∶3(n−6) vs OL prevented any BP increase over the four-wk stress period (p<0.001). Stress increased heart rate in all groups except 20∶4(n−6). Heart rate was lowered by 18∶3(n−6) vs OL (p<0.01) before and during stress. Vascular reactivity to NOR was unaffected by treatment, but OL and 18∶3(n−6) decreased responses to ANG infusion. These data suggest that 18∶3(n−6) supplementation attenuates cardiovascular responses to chronic stress, and that Δ6- and Δ5-desaturase activity are inhibited during chronic psychological stress.

Attenuation of cyclosporine-induced hypertension by dietary fatty acids in the borderline hypertensive rat

The effects of dietary (10% calories) safflower (SAF), evening primrose (EPO), and fish oil (F) as sources of linoleic acid (control), gamma-linolenic acid, and long-chain n-3 fatty acids, respectively, on cardiovascular and renal responses to chronic (5 weeks) cyclosporine administration were studied in male borderline hypertensive rats. In one experiment (n = 9/group), oral administration of CsA at 0.1 mg/kg.day significantly increased awake systolic blood pressure vs. placebo in SAF-fed rats (P less than 0.01). This increase was prevented by both EPO (P less than 0.001) and F (P less than 0.01), in the absence of group differences in body weight gain or plasma electrolyte levels. In a second experiment, CsA also increased blood pressure vs. placebo in SAF-fed rats (P less than 0.001). While this increase was prevented by EPO (P less than 0.001), F had no significant effect. Differences in group blood pressure responses were not explained by group differences in body weight gain or trough levels of blood CsA. Renal function, assessed in anesthetized rats after week 5, demonstrated a CsA-related (10 mg/kg.day) decrease in whole-kidney GFR in SAF-fed animals vs. placebo (P less than 0.05) that was prevented by EPO and attenuated by F. EPO and F also tended to reduce the CsA-induced elevation in renovascular resistance, but this difference did not reach statistical significance. These findings suggest the potential of dietary EPO and F to offset nephrotoxic effects of CsA administration, and suggest that EPO may also be useful in countering CsA-induced hypertension.

Gamma linolenic acid attenuates cardiovascular responses to stress in borderline hypertensive rats

The purpose of the present study was to investigate the effects of gamma linolenic acid (GLA) on cardiovascular responses to psychosocial stress (isolation) and to pressor hormones in the genetically borderline hypertensive rat (SHR×WKY). Adult male SHR×WKY were divided into two groups following five weeks of group housing. One group (GLA) received eight weeks constant flow osmotic pumps releasing 0.04 mg GLA in olive oil/kg-hr, while the second group received dummy pumps (DUM). One week following pump implantation, each group was divided into two subgroups and exposed to a four-week experimental period of either continued group housing (no stress) or isolation (stress). A two-week recovery period of group housing followed the experimental period. Blood pressure and heart rate were determined weekly by the tail cuff technique. At the end of the recovery period, animals in the no stress condition were anesthetized and received an arterial cannula for NOR and ANG infusion and direct BP recording. Then the responses to an ED50 of NOR and ANG were determined. All animals were then killed for determination of heart weight and adrenal weight. All groups had mean control period systolic BP values ranging from 143–146 mm Hg. In the no stress condition, neither GLA nor DUM altered BP over the course of the study. However, BP increased in the DUM group durign all four weeks of the isolation period vs the control period (p<0.01), whereas BP increased only in week 1 in the GLA group (p<0.05). Heart rate increased during stress in the DUM group (p<0.05), but not in the GLA group. Vascular reactivity to NOR was unaffected by GLA administration. In contrast, GLA increased the duration of the pressor response to ANG (p<0.01), but tended to decrease the magnitude of the pressor response (p<0.09) vs DUM. GLA had no effect on heart weight/body weight ratio. Adrenal weight/body weight ratio was lower in the DUM/no stress group than all other treatment groups.These data indicate that GLA administration attenuates the cardiovascular responses to chronic stress in animals with a genetic predisposition to hypertension, in the absence of an effect on resting BP. They also demonstrate a limitation of GLA effect, in mature animals, to epigenetic pressor factors. Furthermore, GLA action may involve an alteration of the cardiovascular responses to ANG, but not NOR. These findings suggest that GLA may be useful in preventing the neurogenic triggering of hypertension by chronic stress in genetically stress-sensitive animals.

Biobehavioral Approaches to Smoking Control

Researchers involved in smoking control face the perplexing question of why, given a reasonable understanding of the adverse effects of smoking, people still start and continue to smoke. Furthermore, although the majority of smokers express a desire to quit, those that attempt to do so are generally unsuccessful (Pechacek, 1979). Numerous programs have been developed that aim not only to aid smokers in their attempts to break the habit but also to prevent the onset of smoking in individuals who represent a population at risk. Unfortunately, these efforts—both smoking prevention and smoking cessation—have been notoriously ineffective (Bernstein & McAlister, 1976; Best & Bloch, 1979; Evans, Henderson, Hill, & Raines, 1979; Flay, d’Avernas, Best, Kersell, & Ryan, 1983; Leventhal & Cleary, 1980; Lichtenstein & Danaher, 1976; Pechacek, 1979; Thompson, 1978). At best, recent interventions such as social-influences prevention programs and nicotine-replacement-therapy cessation strategies appear promising but have not been fully evaluated.