8/3/2019 Chair Restraint in Monkey

http://slidepdf.com/reader/full/chair-restraint-in-monkey 1/7

Adrenergic and Dopaminergic Response to

Chronic Chair Restraint in the Rhesus Monkey

MARK J. PERLOW, MD, FAROUK KAROUM, PHD, DELORES BRAUN, AND

RICHARD JED WYATT, MD

Prolonged chair restraint and social isolation in the rhesus monkey led to a reduction in the

urinary excretion of HVA (4-hydrdxy-3-methoxyphenylacetic acid), DOPAC (3,4-

dihydroxyphenylacetic acid), VMA (3-methoxy-4-hydroxymandelic acid), and MHPG (3-

methoxy-4-hydroxyphenylethylglycol) over a 3 week period. This adaptation to a chronically

"stressful" situation corresponds to earlier studies on the rhesus monkey indicating a gradual

reduction in the urinary excretion of norepinephrine and epinephrine after initiation of re-

straint.

The following basic information on the urinary excretion of catecholamine metabolites was

obtained: (1) the rate of excretion of the dopamine metabolites (HVA and DOPAC) is about four

times higher than the rate of excretion of adrenergic metabolites (VMA and MHPG); (2) MHPG is

the major adrenergic metabolite in the rhesus monkey; and (3) the excretion rates of the urinary

metabolites varied considerably between animals.

INTRODUCTION

Over 60 years ago, W.B. Cannon dem-onstrated that emotional stimuli could

cause the adrenal gland to secretecatecholamines (1). Since then, there havebeen numerous studies investigating theeffects of various psychological stimuli onpituitary-adrenocortical and sympa-

thetic-adrenal medullary activity. Only asmall number of these studies have inves-tigated the biologic response of animals tochronic situational changes (2, 3), and few

deal with primates.

With this as background, we decided toinvestigate the response of monkeys tolong-term chair restraint and social isola-

From the Laboratory of Clinical Psychophar-macology, Division of Special Mental Health Re-search, Intramural Research Program, National Insti-tute of Mental Health, St. Elizabeth's Hospital, Wash-ington, D.C. 20032.

Address reprint requests to: Mark J. Perlow, M.D.,Laboratory of Clinical Psychopharmacology, Wil-liam A. White Building, Room 536, St. Elizabeth'sHospital, Washington, D.C. 20032.

Received for publication May 10, 1978, final revi-sion received November 28, 1978.

tion. These environmental changes were

felt to have a primary, although not exclu-sively, psychological effect upon the ani-mal. By studying the monkey in this

paradigm, we have been able to demon-strate changes in the excretion ofcatecholamine metabolites at variousstages in the adaptation to a novel andstressful situation.

METHODS

Male rhesus monkeys [Macaca mulatto), weighing

5.1 — 7.0 kg, were studied. They were housed in indi-

vidual cages for at least 2—3 months before chair

restraint. The animals were anesthetized with

ketamine hydrochloride (50 mg, I.M.) (Parke, Davis,

Detroit, Mich.), and placed in a primate restrainingchair. After recovery from the effects of the anesthe-

tic (0.5 — 1 hour), the chair and monkey were placed

in a well-ventilated, sound-attenuated chamber with

12 hours of fluorescent light (6:00 A.M .-6:00 P.M.)and 12 hours of darkness (6:00 P.M.-6:00 A.M.). A

standard primate diet of food pellets (Purina Monkey

Chow) and apples was dispensed each morning

(8:00-10:00 A.M.), and the aimals fed themselves.

Water was allowed ad lib. up to 800 ml/day (4, 5).

Each chamber was fitted with a giant funnel to col-

lect urine. As the urine was excreted, it was sepa-

Psychosomatic Medicine Vol. 4 1 , No. 2 (March 1979)

Copyright " 1979 by the American Psychosomal

Published by Elsevier North Holland, Inc.

139

0033-3174/79/02013907/$01.75

8/3/2019 Chair Restraint in Monkey

http://slidepdf.com/reader/full/chair-restraint-in-monkey 2/7

M . J. PERLOW ET AL.

rated from the feces by a gauze filter, collected inplastic bottles (Nagle, Rochester, N. Y.), and im-mediately frozen at -40°C. 24-hour urines were sub-sequently stored at -1 0°C for 3 months. The first dayof urine collection began approximately 24 hoursafter the ketamine anesthesia and initiation of chairrestraint. For biochemical analysis, three consecu-tive 24-hour samples were defrosted and mixed to-gether with 15 ml of 10% disodium ethylenediaminetetraacetate. An aliquot of this mixture was refrozeri

(-80°C) and assayed 1-2 months later for total3-methoxy-4-hydroxyphenylethylglycol (MHPG),and free 3-methoxy-4-hydroxymandelic acid(VMA), 4-hydroxy-3-methoxyphenylacetic acid(HVA), and 3,4-dihydroxy phenylac etic acid(DOPAC) using gas chromatographic mass spectros-copic methodology (6). In these analyses deuteratedMHPG PH3-MHPG), DOPAC PHs-DOPAC), HVA(2H3-HVA), and VMA (2Hs-VMA) were used as inter-nal reference standards. 25 mg of each of these refer-ence standards was added to each sample at the be-ginning of the assay. To quantify the amount of thefree acid metabolites present in the samples, freeVMA, DOPAC, and HVA (25, 50, and 100 mg) wereadded to one urine sample in triplicate at the begin-ning of the analysis. From the difference between theamount of substance present in the urine with andwithout these latter standards, calibration curveswere constructed and used to quantify the amount offree acids present in each urine sam ple. The methylester pentafluoropropionyl derivatives of the acidmetabolites were prepared and analyzed (6).

For the quantification of total MHPG, the sulfateand glucuronide conjugates of MHPG were first hyd-rolyzed with a crude sulfatase preparation (SigmaChemical Co., St. Louis, Mo.) as previously reported(6). After hydrolysis, MHPG was extracted into ethylacetate and measured essentially as described for theacid metabolites. The pentafluoropropionyl deriva-tive was prepared for MHPG analysis.

Separation of the different metabolites wasachieved on an 8-ft 1-in i.d. steel column packedwith 3% SE 54 coated on 80/100 mesh chromosorb G(Pierce Chemical Co., Rockford 111.). A Finniganmodel 3200 quadrupole gas chromatograph massspectrometer was used. The fragments employedfor mass fragmentography were as previously re-ported (6).

RESULTS

The pattern of urinary excretion ofcatecholamine metabolites in the 3-day

period immediately after initiation ofchair restraint is presented in Table 1.Even after correction for body weight dif-ferences, there is considerable inter-mon-key variation in the rate of excretion of allfour m etabolites. For individual monkeys,the magnitude of the variation in excre-tion rates between the highest and lowest

rates for HVA, DOPAC, MHPG, and VMAis 2.7, 9.5, 1.7, and 2.9, respectively. Al-though there is no consistent correlationrelationship between the excretion ratesof each of the metabolites for individualanimals, the individual rate of excretionof the dopamine metabolites, HVA andDOPAC, is greater than the excretion ofthe norepinephrine and epinephrinemetabolites, VMA and MHPG, and theexcretion of MHPG is greater than theexcretion of VMA.

Using a repeated measure analysis of var-iance for a single factor, we are able todemonstrate a reduction in the excretionof MHPG (F = 4.16, p = 0.030), VMA (F =2.03, p = 0.162), HVA (F = 3.60, p =0.046), and DOPAC (F = 3.67, p = 0.056)over the experimental period. By days19—21, the respective excretion rates ofMHPG, VMA, HVA, and DOPAC were68.7, 76.4, 67.5, and 77.2% of the ratesobserved on days 2-4. A Newman-Keulstest demonstrated a significant fp < 0.05)difference in the rates of excretion of

TABLE 1. Urinary Excretion of CatecholamineMetabolites in Monkeys Immediately After ChairRestraint (/xg/kg/24 hr)

Monkey

707

508

706854

842

Weight (kg)

5.1

5.65.2

6.0

7.0

HVA

835

419327

48 0

380

DOPAC

193

146

93

881

563

MHPG

123

80104

135

117

VM A

96

24

70

44

33

140 Psychosomatic Medicine Vol. 41 , No . 2 (Marc h 1979)

8/3/2019 Chair Restraint in Monkey

http://slidepdf.com/reader/full/chair-restraint-in-monkey 3/7

CAT ECH OL AMIN ERC IC RESPONSE TO STRESS

MHPG, HVA, and DOPAC between days2-4 and days 19-21.

Body locomotor activity, although notspecifically monitored, appeared to beunchanged during the experimentalperiod. Dietary intake was measured dailyand was constant during the experimentalperiod, and for the 1-month period after

this investigation, during which the ani-mal remained restrained.

DISCUSSION

Various naturally occurring and ex-perimental paradigms have been used tostudy the catecholamine response to lifesituations, especially those considered tobe stressful (2, 3). A great many experi-ments have used rodents and subjectedthem to stress in the form of muscleexhaustion, environmental temperatureextremes, limb ischemia, electric shock,shaking, paradoxical sleep deprivation,swimming, hemorrhage, and immobiliza-tion (7-3 3). Although the actual concen-

Uj

IZ 8 0

• MHPG

O VMA

\ ^ A HVA

A OOPAC

0 5 10 15 20 25

DAYS

Fig. 1. Urinary excretion of catecholamine metabo-lites in monkeys after chair restraint. Valuesfor each metabolite is expressed as percentof quantity of metabolite excreted on days2 - 4 .

tration of catecholamines in brain tissuedid not consistently increase or decrease,the authors generally agreed thatnorepinephrine turnover in the brain wasincreased during acutely stressful situa-tions.

In situations where brain tissue couldnot be examined, as with most human

studies, catecholamine studies have reliedupon biochemical analyses of urine andblood. Most authors would agree thatconcentration changes of plasma and uri-nary catecholamines and catecholaminemetabolites reflect alterations in the turn-over rate of catecholamines. With stressesof various types the concentration ofnorepinephrine and epinephrine increase(2, 34-46). Representing only 0.5-6.0%of that released from synaptic nerve end-ings (40, 47-49), a fluctuation in theurine concentration of norepinephrineand epinephrine corresponds to similarchanges in the concentration of urinaryVMA (42, 47). For the 3-day period afterinitiation of chair restraint, monkeys ex-creted approximately 8 /u.g of epinephrineand norepinephrine per day (46, 50). Inthe experiment presented here, in simi-larly prepared animals, the monkeys ex-creted 946 fxg (range 581-1,120 /Ag) ofVMA and MHPG per day.

Chair restraint produced a threefold in-crease in urinary epinephrine and a

twofold increase in urinary norepinep-hrine (46,50). The urinary excretion ratesfor these compounds returned to stablebase-line levels after 1 week. The patternsof urinary norepinephrine and epinep-hrine excretion do not correspond to themore gradual reduction in the excretion ofMHPG or VMA. Urine MHPG and VMAexcretion rates declined 31.3 and 23.6%,respectively, over a 21-day period. Thecause for this difference in excretion isunknown but merits further study.

Psychosomatic M edicine Vo l. 41 , No . 2 (March 1979) 141

8/3/2019 Chair Restraint in Monkey

http://slidepdf.com/reader/full/chair-restraint-in-monkey 4/7

M . J. PERLOW ET AL.

The decline in norepinephrine metabo-lism may be the resu lt of adaptation to thephysical restraint itself, or, as a result ofprolonged social isolation and reductionof stimulation from environment. Socialisolation results in behavioral abnor-malities in monkeys (51) and, in rodents,is associated with a decrease in brain

dopamine and norepinephrine turnover,and a reduction in adrenal catecho-lamine-synthesizing enzymes (53-57).

"Stress" in rodents has been shown toalter the concentration and the turnover ofdopamine in brain tissue (7-11, 13, 14,18, 20, 22, 52, 58-61). Unlike no repinep-hrine, where there is a general agreementthat "stress" increases norepinephrineturnover, there is no concensus of opinionas to whether dopamine turnover in-creases, decreases, or remains unchangedin response to stress. This variation mayreflect variations in the strain of animalstudied, the stressor used, the intensityand duration of the stressor and the por-tion of the brain studied. As the monkeysadapted to the novel environment, theyexcreted smaller amounts of DOPAC andHVA, suggesting that over the 3-weekstudy period there was a reduction indopamine turnover. Because we are un-able to determine if the metabolities comefrom the central or the peripheral nervoussystem, we are unable to determine if

dopamine turnover in the brain decreasedduring chair adaptation.When normal volunteers or individuals

with psychiatric illnesses were exposed todifferent environmental situations, theyexcreted varying amounts of norepinep-hrine and epinephrine (2, 34, 35, 37-41,43, 48, 61). Analyses of these results haveled investigators to hypothesize that: (1)the concentrations and the ratio of urinaryepinephrine/norepinephrine response inan individual's behavioral state and the

manner in which he will respond to theinducing stimulus, and (2) thenorepinephrine and ep inephrine responseis a reflection of this general response tothe inducing stimulus. We had hoped thatour experiment would extend the observa-tions that serve as bases for these hypoth-eses (46,50). As a result of previous

studies in which norepinephrine weremeasured (46,50), we felt that the amountof urinary adrenergic metabolites wouldincrease with chair restraint. As urinaryVMA is considered to have its origin inpools of catecholamines outside the brainand urinary MHPG to have its origin inpools of norepinephrine in both the bodyand the brain (62), we postulated thattheir differential increase would reflectthe peripheral and central adrenergic re-sponse to the stressor. We also hoped thatas the animals adapted to the chair re-

straint and social isolation, and theamounts of catecholamine metabolitesdecreased, the ratio of VMA/MHPG wouldchange reflecting perhaps, a change inexcretion patterns of epinephrine andnorepinephrine, an alteration inmetabolic pathway for the metabolism ofepinephrine and/or norepinephrine, or adifferential rate of adaptation of the cen-tral vs. peripheral nervous systems to thestressor. Since the rate of decline of uri-nary excretion of MHPG and VMA was

similar, we were unable to speculate uponthe above propositions.

Despite a similarity of sexual gender,age, and body weight, there was consider-able variation between animals in excre-tion of catecholamine metabolites. A simi-lar variation was noted in earlier studiesmeasuring the excretion of catecho-lamines and catecholamine metabolites(2, 33-37, 40, 41, 45, 48, 61, 63-66). On akilogram basis, the variation betweenhighest and lowest excretion rates for

142 Psychosomatic Medicine Vol. 41 , No . 2 (March 1979)

8/3/2019 Chair Restraint in Monkey

http://slidepdf.com/reader/full/chair-restraint-in-monkey 5/7

CAT ECH OLA MINE RG IC RESPONSE TO STRESS

HVA, DOPAC, MHPG, an d VMA is dopaminergic metabolites decreases over2.7,9 .5,1.7 , and 2.9, res pe ctiv ely . Al- several weeks after initiation of chronicthough the ratio of MHPG/VMA is always chair restra int. Despite a considerable var-> 1, the ratio of HVA/DOPAC varies be- iation in base-line excretion rates, the ratetween 0.54 and 4.3. The relative excretion of decline of all metabolites is the same,rate of metabolites between animals and We note the possible usefulness in usingthe ratio of adrenergic and dopaminergic metabolites of catecholamines to followmetabolites in the urine was unchanged the biochemical response to a "stressor."

after 3 months of chair restraint (unpub-lished data). The authors wish to thank M. Strot-

From these results we conclude that the kamp and M. Adam s for their assistanceexcretion of adrenergic metabolites and in the preparation of this paper.

REFERENCES

1. Cannon WB, De La Paz D: Emotional stimulation of adrenal secretion. Am J Physiol 27:6 4-7 0, 19112. Frankenhaeuser M: Experimental approaches to the study of catecholamines and emotions, in Levi L

(ed.), Emotions—Their Parameters and Measurement. New York, Raven Press, 1975, pp. 209-2343. Mason JW: Emotion as reflected in patterns of endocrine integration, in Levi L (ed.), Emotions—Their

parameters and Measurement. New York, Raven Press, 1975, pp. 143-181

4. Mason JW: Restraining chair for the experimental study of primates. J Appl Physiol 12:130—133, 19585. Perlow M, Ebert MH, Gordon EK, et al: The circadian variation of catecholamine metabolism in the

subhuman primate. Brain Res 139:101-113, 19786. Karoum F, Gillin JC, Wyatt RJ, et al: Mass fragmentography of nanogra m qua ntities of biogenic am ine

metabolites in human cerebrospinal fluid and whole rat brain. Biomed Mass Spect 2:183-189, 19757. Avakian OM, Shirinian EA: The sympathetic-adrenal system and hemorrhagic shock, in Usdin E,

Kvetnansky R, Kopin I, (ed.), Catecholamines and Stress. Oxford, Pergamon Press, 1976, pp. 476—4828. Barchas JD, Freedman DX: Response to physiological stress. Biochem Pharmacol 12:123 2-123 5,19639. Bliss EL, Ailion J, Zwanziger J: Metabolism of norepine phrine, serotonin and dopamine in rat brain

with stress. J Pharmacol Exp Ther 164:122-134, 196810. Bliss EL, Ailion J: Relationship of stress and activity to brain dopam ine and homovanillic acid. Life Sci

10:1161-1169, 197111. Bliss EL, Zwanziger J: Brain amines and emotional stress. J Psychiatr Res 4:189-198, 196612. Carr LA, Moore KE: Effects of reserpine and a-methyl-tyrosine on brain catecholamines and the

pituitary-adrenal response to stress. Neuroendocrinology 3:285—302, 1968

13. Corrodi H, Fuxe K, Lidbrink P, et al: Mild tranquilizers, stress and central catecholamine ne urons. BrainRes 29:1-16, 1971

14. Gibson S, McGreer EG, McGreer PL: Metabolism of catecholamines in cold-exposed rats. J Neurochem10:1491-1493, 1969

15. Kety SS, Javoy F, Thierry AM, et al: A sustained effect of electroconvulsive shocks on turnover ofnorepinephr ine in the central nervous system of the rat. Proc Natl Acad Sci USA 5 8:1249-12 54, 1967

16. Korf J, Aghajanian GK, Roth RH: Increased turnover of norepinephrine in the rat cerebral cortex duringstress: role of the locus coeruleus. Neuropharmacology (Oxford) 1 2:933 -938 , 1973

17. Kvetnansky R, Kopin IJ: Activity of adrenal catecholamine-producing enzymes and their regulationafter stress, in Kovach AGB, Stoner HB, Spitzer JJ (eds.), Neurohumoral and Metabolic Aspects of Injury.New York, Plenum Press, 1975, pp. 55-56

18. Lidbrink P, Corrodi H, Fuxe K, et al: Barbiturates and m eprobamate: decrease in catecholamine turnoverof central dopamine and noradrenaline neuronal systems and the influence of immobilization stress.Brain Res 45:507-524, 1972

Psychosomatic Medicine Vol. 41, No . 2 (March 1979) 143

8/3/2019 Chair Restraint in Monkey

http://slidepdf.com/reader/full/chair-restraint-in-monkey 6/7

M. J. PERLOW ET AL.

19. Matussek M, Ruhner E, Ackenheil M, et al: Amine metabolism in the central nervous system duringexhaustion after swimming and the influence of antidepressants on this syndrome. Excerpta Med IntCong Ser 122:70-74,196 7

20. Maynert EW, Levi R: Stress induced release of brain norepinephrine and its inhibition by drugs. JPharmacol Exp Ther 143:90-95, 1964

21. Moore KE, Lariviere EW: Effect of stress and d-amphetamine on rat brain catecholamines. BiochemPharmacol 13:1098-1100, 1964

22. Palkovits M, Kobayashi RM, Kizer JS, et al: Effects of stress on catecholamines and tyrosine hydroxylaseactivity on individual hypothalamic nuclei. Neuroendocrinology 18:144—153, 1975

23. Pujol JF, Mouret J, Jouvet M, et al: Increased turnover of cerebral norepinephrine during rebound of

paradoxical sleep in the rat. Science 159:112-114, 196824. Schildkraut JJ, Draskarg PR, Lo PS: Norepinephrine pools in rat brain: differences in turnover rates and

pathways of metabolism. Science 172:587-589, 197125. Simmonds MA: Effect of environmental temperature on the turnover of oradrenaline in the

hypothalamus and other areas of the rat brain. J Physiol (Lond) 203:199, 196926. Stone EA: Accumulation and metabolism of norepinephrine in rat hypothalamus after exhaustive

stress. J Neurochem 21:5 89-6 01, 1973.27 . Stone EA: Effect of stress on sulfated glycol metabolites of brain norepinephrine. Life Sci

16:1725-1730, 197528. Stoner HB, Elson PM: The effect of injury on monoamine concentrations in the rat hypothalamus. J

Neurochem 81:1837-1846, 197129. Taylor K, Laverty R: The interaction of chlordiazepoxide diazepam and itrazepam and histamine in

regions of the rat brain, in Garattini S, Mussini E, Randall L (eds.), The Benzodiazepines. New York,Raven Press, 1973, pp. 121-202

30. Thierry AM, Javoy F, Glowinski J, Kety SS: Effects of stress on the metabolism of norepinephrine,dopamine and serotonin in the central nervous system of the rat. I. Modifications of norepinephrineturnover. J Pharmacol Exp Ther 163:163-171, 1968

31. Thoenen H, Otten U, Oesch F: Transsynaptic regulation of tyrosine hydroxylase, in U sdin E, Snyder SH(eds.), Frontiers in Catecholamine Research. New York, Pergamon Press, 1973, pp. 179 -18 5

32. Welch AS, Welch BL: Reduction of orepinephrine with lower brain stem with psychological stimu lus.ProcNatl Acad Sci USA 60:478-483, 1968

33. Welch BL, Welch AS: Differential activation by restraint stress of a mechanism to conserve braincatecholamines and serotonin in mice differing in excitability. Nature 218:575-58 0, 1968

34. Ax A: The physiological differentiation between fear and anger in hum ans. Psychosom Med 15:433,1953

35. Bergsman A: The urinary excretion of adrenaline and norad renaline in some mental diseases: a clinicaland experimental study. Acta Psychiatr Scand [Suppl 133] 34:1959

36. Bloom G, Euler USv, Frankenhaeuser M : Catecholamine excretion and personality traits in paratrooptrainees. Acta Physiol Scand 58:77, 1963

37. Curtis GC, Cleghorn RA, Sourkes TL: The relationship between affect and the excretion of adrenaline,noradrenaline and 17-hydroxycortico-steroids. J Psychosom Res 4:176 -184 , 1960

38. Euler USv, Genzell CA, Levi L, et al: Cortical and medullary adrenal activity in emotional stress. ActaEndocrinol (Kbh) 30:567-573, 1959

39. Euler USv, Lundberg: Effect of flying on the epinephrine excretion in Air Force personnel. J ApplPhysiol 6:551-555, 1954

40 . Elmadjian F, Hope JM, Lamson ET: Excretion of epinephrine and norepine phrine under stress. RecentProg Horm Res 14:513-553, 1958

41. Funkenstein DH: Norepinephrine-like and epinephrine-like substances in relation to human behavior.J Nerv Ment Dis 124:58-68, 1956

42 . Goodall McC, Berman ML: Urinary output of adrenaline, noradrenaline, and 3-methoxy-4-hydroxymandelic acid following centrifugation and anticipation of centrifugation. J Clin Invest39:1533-1540, 1960

43. Hickam JB, Cargill WH, Golden A: Cardiovascular reactions to emotional stimuli. Effect on cardiacoutput, arteriovenous oxygen difference, central pressure, and peripheral resistance. J Clin Invest27:290-298, 1948

144 Psychosomatic Med icine Vo l. 41 , No . 2 (March 1979)

8/3/2019 Chair Restraint in Monkey

http://slidepdf.com/reader/full/chair-restraint-in-monkey 7/7

CAT ECH OLA MINE RG IC RESPONSE TO STRESS

44. Levi L: Sympatho-adrenomedullary and related biochemical reactions during experimentally inducedemotional stress, in Michael RP (ed.), Endocrinology and Human B ehavior. London, Oxford U niversityPress, 1968, pp. 200-219

45. Life Sciences Research Office. The military applicability of research on quantification of stress bycatecholam ine analy sis. Fed Am Soc Exp Biol 1967

46. Mason JW: A review of psychoendocrine research in the sympathetic-adrenal medullary system.Psychosom Med 30:631-653, 1968

47. Euler USv: Pathophysiological aspects of catecholamine production. Clin Chem 18:1445-1448, 197748. Elmadjian F, Lamson ET, Nervi R: Excretion of adrenaline and n oradrenaline in hum an subjects. J Clin

Endocrinol Metab 16:222-234, 1956

49. Resnick O, Elmadjian F: Metabolism of epinephrine containing isotopic carbon in man. J Clin Endoc-rinol Metab 18:28-35, 1958

50. Mason JW, Mougey EH, Kenion CC: Urinary epinephrine and noradrenaline responses to chair res-traint in the monkey. Physiol Behav 10:801-804, 1973

51. Harlow HF, Dodsworth RO, Harlow MK: Total social isolation in monkeys. Proc Natl Acad Sci USA54:90-97, 1965

52 . Antelman SM, Caggiula AR: Norepinephrine-dopamine interactions and behavior. Science195:646-653, 1977

53. Axelrod J, Mueller RA, Henri JP, Stephens PM: Changes in enzymes involved in the biosynthesis andmetabolism of noradrenaline and adrenaline after psychosocial stimulation. Nature (Lond)225:1059-1060, 1970

54. Modigh K: Effects of isolation and fighting in mice on the rate of synthesis of noradrenaline, dopamineand 5-hydroxytryptamine in the brain. Psychopharmacology 33:1 — 17, 1973

55. Thoa NB, Tizabi Y, Jacobowitz DM: The effect of isolation on catecholamine concentration and turnoverin discrete areas of the rat brain. Brain Res 131:259-269, 1977

56. Welch BL, Welch AS: Greater lowering of brain and adrenal catecholamines in group-housed miceadministered DL-alpha-methyltyrosine. J Pharm Pharmacol 20:24 4-246 , 1968

57. Welch BL, Welch AS: Sustained effects of brief daily stress (fighting) upon brain and adrenalcatecholamines and adrenal, spleen, and hea rt w eight of mice. Proc Natl Acad Sci USA 64:100 — 107,1969

58. Gordon R, Spector S, Sjoerdsma A, Udenfriend S: Increased synthesis of norepineph rine and e pinep-hrine in the intact rat during exercise and exposure to cold. J Pharmacol Exp Ther 153:440-447, 1966

59. Kvetnansky R, Mitro A, Palkovits M, Brownstein M, et al: Catecholamines in indiv idual hypothalamicnuclei in stress rats, in Usdin E, Kvetnansky R, Kopin IJ (eds.), Catecholamines and Stress. New York,Plenum Press, 1975, pp. 55 -56

60. Thierry AM, Tassin JP, Blanc G, et al: Selective activation of the mesocortical DA system by stress.Nature (Lond) 263:242-244, 1976

61. Frankenhaeuser M, Kareby S: Effect of meprobamate on catecholamine excretion during mental stress.Percept Mot Skills 15:571-580, 1962

62. Maas JW, Fawcett JA, Dekirmenjian H: Catecholamine metabolism depressive illness, and drug re-

sponse. Arch Gen Psychiatry 26:252-258, 197263. Davies, TW, deMonchaux C: Mood changes in relation to personality and the excretion of 3-methoxy-

4-hydroxymandelic acid. Psychosom Med 35:205-214, 197364. Frankenhaeuser M, Mellis I, Rissler A, et al: Catecholamine excretion as related to cognitive and

emotional reaction patterns. Psychosom Med 30:109-120, 196865. Frankenhaeuser M, Patkai P: Catecholamine excretion and performance during stress. Percept Mot

Skills 19.13-20, 196466. Silverman AJ, Cohen Si, Shamovian BM, et al: Catecholamines in psychophysiologic studies. Recent

Adv Biol Psychiatr 3:104, 1961

Psychosomatic Medicine Vol. 41 , No . 2 (March 1979) 145