Cortisol levels and serum antioxidant status following chemotherapy

doi:10.4236/health.2011.38085

Paper Menu >>

Journal Menu >>

Vol.3, No.8, 512-517 (2

doi:10.4236/health.2011.38085

011) Health

Cortisol levels and serum antioxidant status following

chemotherapy

Eugenia Limberaki1, Phaedra Eleftheriou1, Georgios Gasparis1, Eugenios Karalekos1, Vassilis

Kostoglou2*, Christos Petrou1

1Department of Medical Laboratory Studies, Alexander Technological Educational Institute of Thessaloniki, Thessaloniki, Greece;

2Department of Informatics, Alexander Technological Educational Institute of Thessaloniki, Thessaloniki, Greece;

*Corresponding Author: [email protected]

Received 28 April 2011; revised 1 July 2011; accepted 13 July 2011.

ABSTRACT

Chemotherapy results in increased free radical

formation and depletion of tissue antioxidants.

Moreover, patients receiving chemotherapy are

under emotional stress, which is also accom-

panied by low antioxidant levels. In the present

study, we measured cortisol, the main stress

hormone, and total antioxidant capacity (TAC)

in serum of 51 cancer patients during chemo-

therapy. Antioxidant activity was estimated by

measuring the influence of serum in oxidation

of ABTS (2,2΄-azino-bis (3-ethylbenz-thiazoline-

6-sulfonic acid to ABTS+ by methmyoglobin

(Antioxidant kit of Cayman). Serum cortisol was

measured using an ELISA colorimetric assay.

Serum TAC was significantly decreased (75%

decrease compared to normal levels, p = 0.001)

in all patients during chemotherapy, while blood

cortisol concentration was increased by 10%, (p

= 0.044). Lower antioxidant levels and higher

cortisol concentration were detected in patients

receiving chemotherapeutic drugs daily, com-

pared to the ones receiving chemotherapy once

a week. A difference between sexes was ob-

served with male patients presenting lower an-

tioxidant status and higher cortisol levels than

females. A significant and persistent decrease

in antioxidant capacity accompanied by in-

creased cortisol concentration was observed in

all patients during chemotherapy. This fact,

which is probably generated by biological and

emotional stress, increases the probability of

harmful side effects and organism weakening

and needs to be considered during patients’

treatment.

Keywords: Antioxidant Capacity; Cortisol;

Chemothera py; Cancer

1. INTRODUCTION

Cancer cells themselves seem to cause a decrease in

antioxidant status [1]. Chemotherapy acts by killing cells

that divide rapidly, one of the main properties of most

cancer cells. Additionally, the action of most chemo-

therapeutic agents is based in creating reactive oxygen

species (ROS) [2,3], and these agents are associated with

depletion of plasma and tissue antioxidants [4-7]. ROS

are cytotoxic molecules and key mediators in signaling

cascades. Increased plasma lipid peroxidation and thio-

barbituric acid–reactive species accompany oxidative

stress induced in patients receiving chemotherapy [8,9].

Glutathione (GSH) concentrations are markedly reduced

by chemotherapeutic agents, such as busulfan, cermust-

ine (BCNU), and cisplatin [10]. Cisplatin is a platinum

containing anti-cancer drug reacting in vivo and causing

cross linking of DNA, which triggers to apoptosis. In ad-

dition, apoptosis induced by cisplatin is inhibited by

ROS scavengers, including N-acetyl cysteine, MnTBAP

and C60. Cisplatin promotes ROS production, which in

turn contributes to Fas receptor aggregation and cell

death. Newer anticancer drugs like nutlins act directly

against abnormal proteins in cancer cells; this is termed

target therapy and is technically not chemotherapy. The-

se drugs kill cancer cells via ROS-independent path-

ways. Phagocytosis of cancer cells may be another rea-

son for the generation of free radicals during chemo-

therapy [11]. The low serum total antioxidant capacity

observed in patients suffering from cancer reflects this

imbalance [12]. Insufficient defense against free radicals

may have harmful results, which may be the reason for

serious undesired side effects of chemotherapy. More-

over, it is hypothesized that ROS may facilitate metasta-

sis [13].

Many patients being treated for cancer receive dietary

supplements, particularly antioxidants, during chemothe-

rapy and radiotherapy [14,15]. Although some preclini-

E. Limberaki et al. / Health 3 (2011) 512- 517

513

cal data show that antioxidants might reduce the effec-

tiveness of chemotherapy [16], other studies report

similar or better response in chemotherapy when com-

bined to antioxidant-rich diet [17-19]. For example,

while an excess in vitamin C is believed to facilitate glu-

cose transportation into cancer cells, thus inducing pro-

liferation [20-22], antioxidant vitamins such as C and E

have been successfully used as supplements for amelio-

rating the side effects of chemotherapy [23,24]. In gen-

eral, if generation of reactive oxygen species by a cancer

chemotherapeutic agent plays a role in its cytotoxicity,

antioxidants may interfere with the drug’s antineoplastic

activity. However, if the reactive species are responsible

only for the drug’s side effects, antioxidants may actu-

ally reduce the severity of such effects without interfer-

ing with the drug’s antineoplastic activity [2,25]. As a

consequence, different forms of antioxidant molecules

have been categorized either as interfering or not inter-

fering with anticancer therapy.

Cortisol, usually referred to as the “stress hormone”,

is involved in the organism’s response to stress and anxi-

ety. It triggers all metabolic mechanisms leading to pro-

duction of compounds used as energy sources in emer-

gency conditions. It increases glucose and free amino-

acid concentration in serum by inducing gluconeogene-

sis, thus inhibiting protein synthesis and promoting hy-

drolysis of lipids and proteins, and mobilization of extra

hepatic amino acids and ketone bodies. Cortisol levels

are affected by the circadian cycle with highest values

observed early in the morning. Increased cortisol con-

centrations are measured in blood serum of people under

biological or emotional stress, depression, sleep depriva-

tion, fever, hypoglycemia, anorexia nervosa and after

surgery [26-28]. A 3% - 10% increase in cortisol levels

has been observed in cancer patients varying according

to the severity of the disease [29]. Cortisol is one of the

main biomarkers of depression and is often used for

monitoring depression therapies [30]. Moreover, in-

crease in cortisol concentration has been associated with

decrease in total antioxidant levels and low total anti-

oxidant capacity (TAC) is a common feature in all con-

ditions where elevated cortisol concentrations are ob-

served [31]. The levels of some tissue antioxidants are

inversely related to cortisol tissue levels [32]. Antioxi-

dant depletion may result as a consequence of various

pathways activated by cortisol or may be the effect of

free radical production during cortisol metabolism, since

oxidative metabolism of cateholamines produces cinones

which react with superoxide anion, Ο2

 , and hydrogen

dioxide, ΗΟ2

. Antidepressant therapy resulting in de-

crease of cortisol levels also results in increase of anti-

oxidant concentration. Moreover, it has been stated that

augmentation of antioxidant defense could serve as an

important mechanism underlying the neuroprotective

pharmacological effects of these drugs [33].

Cancer patients on chemotherapy are under strong

biological and emotional stress. This may lead to high

cortisol levels which may be an additional cause for the

reduction of protective antioxidants and induction of

undesired side effects.

In this study, we measured the total antioxidant capac-

ity and cortisol levels in serum of 51 cancer patients re-

ceiving chemotherapeutic agents once a day or once a

week and compared the concentrations of the two para-

meters between 1) patients and healthy people, 2) pa-

tients receiving the treatment once/day and once/week),

and 3) patients of different sex.

2. METHODS

In the present study, the level of total blood antioxi-

dants and cortisol levels were measured in blood serum

of 51 (18 male and 33 female) Greek cancer patients on

chemotherapy. All blood samples were collected before

treatment between 8.00 and 9.00 a.m. All patients were

volunteers, informed about the project, and did not fol-

low any specific diet. The serum samples were stored for

3 - 15 days at –80˚C (Serum can be stored at –80˚C for 1

month as it is described in the Technical Bulletin of An-

tioxidant Assay Kit of Cayma). Lipemic and hemolysed

samples—when found—were excluded. 19 of the pa-

tients received their chemotherapy agents once a day and

32 received their therapy once a week. Most chemo-

therapy agents consisted of busulfan, etoposide and

cyclopjosphamide, or cytosine, diaziquone and thiotepa.

For comparisons, samples from 32 men and women of

about the same age with no known health problem were

also collected and used as controls.

Evaluation of TAC was done using the antioxidant

Assay Kit of Cayman. Serum cortisol was measured

using the immunoenzyme assay kit of HUMAN. Ab-

sorbance rates were measured using START-FAX 2100

microtitre plate reader.

2.1. Evaluation of Serum Total Antioxidant

Capacity

TAC measurement was carried out using the antioxi-

dant Assay Kit of Cayman. Antioxidants inhibit the oxi-

dation of ABTS (2.2΄-azino-di 3-ethylbenthiazoline-

sulfonate) to ABTS+ by methmyoglobin. Trolox, the

water soluble analogue of vitamin E, was used as control.

Antioxidant concentration is quantified in millimolar

Trolox equivalents [34].

2.2. Evaluation of Serum Cortisol

Serum cortisol was measured using the immunoen-

E. Limberaki et al. / Health 3 (2011) 512- 517

514

zyme assay kit of HUMAN. The method is based on

competitive interaction of serum cortisol and a cortisol-

enzyme conjugated provided by HUMAN for a limited

number of monoclonal anti-cortisol antibodies bound to

the wells of a microtitre ELISA plate. The amount of the

bound hormone-enzyme conjugate is inversely propor-

tional to the concentration of cortisol in the specimen.

After removal of unbound conjugate by washing, a sub-

strate solution is added and a blue color develops which

changes to yellow by the addition of stop solution. The

absorbance is measured at 450 nm using a mictotitre

plate reader. Concentration of unknown specimens is

interpolated from a dose response curve generated by

utilizing serum calibrators of known cortisol concentra-

tion [35].

2.3. Statistical Analysis

Statistical analysis of data was carried out with SPSS

[36]. The Student’s t test for independent samples was

used to compare the blood samples of cancer patients

with them of healthy people. As this type of data follow

the normal distribution, we used the Student t-test to

detect significant differences between groups.

3. RESULTS

Measurement of the TAC in blood serum of 51 cancer

patients receiving chemotherapy and 32 healthy indi-

viduals of the same age revealed a 75% decrease in se-

rum antioxidants of treated cancer patients (p = 0.001

according to the Student’s t-test). Measurement of corti-

sol levels in the same blood samples revealed a 10%

increase in cortisol concentration in the patients’ group

(p = 0.044) (Figure 1).

TAC decrease was greater in patients receiving che-

motherapy once a day compared to the patients receiving

chemotherapy once a week (Figure 2).

Figure 1. Total antioxidant capacity and cortisol levels in

blood serum of cancer patients receiving chemotherapy (n = 51)

and healthy individuals (n = 32) of the same age (significance

levels according to the Student’s t-test: *p = 0.044, **p =

0.001). The vertical bars represent standard deviation (SD).

Figure 2. Total antioxidant capacity and cortisol levels in

blood serum of cancer patients receiving chemotherapy once a

day (n = 19) and once a week (n = 32) (significance levels

according to the Student’s t-test: *p = 0.101, **p = 0.001). The

vertical bars represent SD.

A statistically significant difference (p = 0.001) was

observed between the two groups of patients with total

blood antioxidant concentration in daily receiving che-

motherapy patients being 37% lower compared to the

weekly treated individuals. Greater elevation of cortisol

levels was measured in daily treated patients (D-T P)

compared to the weekly treated (W-T) ones. A 27% in-

crease in cortisol values of D-T P group was observed

compared to the W-T group (p = 0.101).

A difference both in TAC and cortisol levels of male

and female patients was also observed. Lower antioxi-

dant levels (21% decrease, p = 0.055) and higher cortisol

levels of poor significance though (29% increase, p =

0.214), were measured in male patients compared to the

female ones as shown in Figure 3.

4. DISCUSSION

Low antioxidant capacity was accompanied by high

cortisol levels in cancer patients on chemotherapy, al-

though some studies showed that cortisol can decrease

Figure 3. Total antioxidant capacity and cortisol levels in

blood serum of male (n = 18) and female (n = 33) cancer pa-

tients receiving chemotherapy (significance levels according to

the Student’s t-test:* p = 0.214, **p = 0.055). The vertical bars

represent SD.

E. Limberaki et al. / Health 3 (2011) 512- 517

515

oxidative stress through inhibition of nuclear factor-κB

[37,38] The decrease in antioxidant capacity reached

72% in weekly treated patients and 82% in daily treated

patients compared to the control group. Since, most of

the chemotherapeutic agents are cleared-off within hours

or a few days, this means that a slight part of the de-

crease observed was due to the presence of the chemo-

therapeutic agent itself and low TAC was observed at

least seven days after application of chemotherapy. This

was a common finding in all patients and was not de-

pendent on the chemotherapeutic agent used. A 10% -

20% decrease in TAC is a common characteristic in pa-

tients suffering from cancer and was observed in benign

and malignant neoplasias [39]. Emotional and biological

stress and cytotoxic procedures may also contribute to

that decrease. Increased cortisol concentrations were

measured in all patients. A 10% average increase was

observed in weekly-treated patients reaching 64% in-

crease in daily-treated patients. Although, a straight rela-

tionship between antioxidant status and cortisol levels

was not obtained from our results, high cortisol concen-

tration may partly contribute to TAC decrease especially

in daily-treated patients.

Exposure to stressful conditions often leads to high

cortisol levels, smoothening at the same time, the dif-

ferences existing because of sex or age [40]. Some pub-

lished studies showed a significant reduction in serum

cortisol immediately after infusion of either cisplatin or

carboplatin and other chemotherapeutic agent like ly-

sodren which works by attacking the cells of the adrenal

glands to inhibit adrenal gland functioning [41].

However, this was not observed in the present study. It

seems that additional excretion of the hormone due to

chemotherapy is added to the already elevated levels in

male patients [42] or that male patients respond in a dif-

ferent way in stressful conditions. Different response to

chemotherapy is also reflected in the antioxidant levels

in serum of the two sexes. Sex differences in symptoms

and response to a therapy has often been observed in

cancer patients [43].

In spite of the suggestion of some researchers that

treatment with antioxidants may reduce the effect of

some anticancer agents, we believe that such a great and

persistent decrease in antioxidant capacity accompany-

ing increased cortisol concentrations augments the prob-

ability of harmful side-effects and may lead to the orga-

nism weakening. We conclude that, depending on the

treatments used against cancer, a special diet or treat-

ment aiming at the improvement of patients’ antioxidant

capacity and reduction of cortisol concentration may

upgrade the health status of patients and their response

to therapies in general.

5. ACKNOWLEDGEMENTS

The authors thank Dr Yannis Kazoglou for useful comments on the

manuscript.

REFERENCES

[1] Skrzydlewska, E., Stankiewicz, A., Sulkowska, M., Sul-

kowski, S. and Kasacka, I. (2001) Aantioxidant status

and lipid peroxidation in colorectal cancer. Journal of

Toxicolog y and E n v ironmental Health, 64, 213-222.

doi:10.1080/15287390152543690

[2] Shacter, E., Williams, J.A., Hinson, R.M., Senturker, S.

and Lee, Y.J. (2000) Oxidative stress interferes with can-

cer chemotherapy: Inhibition of lymphoma cell apoptosis

and phagocytosis. Blood, 96, 307-313.

[3] Lee, Y.J. and Shacter, E. (1999) Oxidative stress inhibits

apoptosis in human lymphoma cells. Journal of Biolo-

gical Chemistry, 274, 19792-19798.

doi:10.1074/jbc.274.28.19792

[4] Weijl, N.I., Leton, F.J. and Osanto, S. (1997) Free radi-

cals and antioxidants in chemotherapy-induced toxicity.

Cancer Tr eatment Reviews, 23, 209-240.

doi:10.1016/S0305-7372(97)90012-8

[5] Durken, M., Agbenu, J., Finckh, B., Hübner, C., Pichl-

meier, U., Zeller, W., et al. (1995) Deteriorating free

radicaltrapping capacity and antioxidant status in plasma

during bone marrow transplantation. Bone Marrow

Transplant, 15, 757-762.

[6] Lauterburg, B.H., Nguyen, T., Hartmann, B., Junker, E.,

Kupfer, A. and Cerny, T. (1994) Depletion of total cys-

teine, glutathione, and homocysteine in plasma by ifos-

famide/mesna therapy. Cancer Chemotherapy and

Pharmacology, 35,132-136. doi:10.1007/BF00686635

[7] Crohns, M., Liippo, K., Erhola, M., Kankaanranta, H.,

Moilanen, E., Alho, H., et al. (2009) Concurrent decline

of several antioxidants and markers of oxidative stress

during combination chemotherapy for small cell lung

cancer. Clinical Biochemistry, 42, 1236-1245.

doi:10.1016/j.clinbiochem.2009.05.003

[8] Ladner, C., Ehninger, G., Gey, K.F. and Clemens, M.R.

(1989) Effect of etoposide (VP16–213) on lipid peroxi-

dation and antioxidant status in a highdose radiochemo-

therapy regimen. Cancer Chemotherapy and Pharma-

cology, 25, 210-212. doi:10.1007/BF00689585

[9] Faure, H., Coudray, C., Mousseau, M., Ducros, V., Douki,

T., Bianchini, F., et al. (1996) 5-Hydroxymethyluracil

excretion, plasma TBARS and plasma antioxidant vita-

mins in adriamycin-treated patients. Free Radical Biol-

ogy and Medicine, 20, 979-983.

doi:10.1016/0891-5849(95)02187-6

[10] Bhuvarahamurthy, V., Balasubramanian, N. and Govin-

dasamy, S. (1996) Effect of radiotherapy and chemo-

therapy on circulating antioxidant system of human uter-

ine cervical carcinoma. Molecular and Cellular Bio-

chemistry, 158, 17-23.

[11] Gadjeva, V., Dimov, A. and Georgieva, N. (2008) Influ-

ence of therapy on the antioxidant status in patients with

melanoma. Journal of Clinical Pharmacy and Therapeu-

tics, 33, 179-185. doi:10.1111/j.1365-2710.2008.00909.x

[12] Papageorgiou, M., Stiakaki, E., Dimitriou, H., Malliaraki,

N., Notas, G., Castanas, E., et al. (2005) Cancer chemo-

therapy reduces plasma total antioxidant capacity in

children with malignancies. Leukemia Research, 29, 11-

E. Limberaki et al. / Health 3 (2011) 512- 517

516

16. doi:10.1016/j.leukres.2004.04.017

[13] Ten Kate, M., van der Wal, J.B., Sluiter, W., Hofland, L.J.,

Jeekel, J., Sonneveld, P., et al. (2008) The role of super-

oxide anions in the development of distant tumour recur-

rence. British Journal of Cancer, 98, 580-586.

[14] Burstein, H.J., Gelber, S., Guadagnoli, E. and Weeks, J.C.

(1999) Use of alternative medicine by women with

early-stage breast cancer. New England Journal of Medi-

cine, 340, 1733-1739.

doi:10.1056/NEJM199906033402206

[15] Van de Creek, L., Rogers, E. and Lester, J. (1999) Use of

alternative therapies among breast cancer outpatients

compared with the general population. Alternative Thera-

pies in Health and Medicine, 5, 71-76.

[16] D’Andrea, G.M. (2005) Use of antioxidants during che-

motherapy and radiotherapy should be avoided. A Cancer

Journal for Clinicians, 55, 319-321.

[17] Pace, A., Savarese, A., Picardo, M., Maresca, V., Pacetti,

U., Del Monte, G., et al. (2003) Neuroprotective effect of

vitamin E supplementation in patients treated with cis-

platin chemotherapy. Journal of Clinical Oncology, 21,

927-931. doi:10.1200/JCO.2003.05.139

[18] Iarussi, D., Auricchio, U., Agretto, A., Murano, A.,

Giuliano, M., Casale, F., et al. (1994) Protective effect of

coenzyme Q10 on anthracyclines cardiotoxicity: Control

study in children with acute lymphoblastic leukemia and

non-Hodgkin lymphoma. Molecular Aspects of Medicine,

15, 207-212.

[19] Weijl, N.I., Elsendoorn, T.J., Lentjes, E.G., Hopman, G.D.,

Wipkink-Bakker, A., Zwinderman, A.H., et al. (2004)

Supplementation with antioxidant micronutrients and

chemotherapy-induced toxicity in cancer patients treated

with cisplatin-based chemotherapy: A randomised, dou-

ble-blind, placebo-controlled study. European Journal of

Cancer, 40, 1713-1723.

[20] Guaiquil, V.H., Vera, J.C. and Golde, DW. (2001) Mecha-

nism of vitamin C inhibition of cell death induced by

oxidative stress in glutathione-depleted HL-60 cells. Jour-

nal of Biological Chemistry, 276, 40955-40961.

doi:10.1074/jbc.M106878200

[21] Lesperance, M.L., Olivotto, I.A., Forde, N., Zhao, Y.,

Speers, C., Foster, H., et al. (2002) Mega-dose vitamins

and minerals in the treatment of non-metastatic breast

cancer: An historical cohort study. Breast Cancer Re-

search and Treatment, 76, 137-143.

doi:10.1023/A:1020552501345

[22] Bjelakovic, G., Nikolova, D., Simonetti, R.G. and Gluud,

C. (2004) Antioxidant supplements for prevention of

gastrointestinal cancers: A systematic review and meta-

analysis. Lancet , 364, 1219-1228.

[23] Greggi Antunes, L.M., Darin, J.D. and Bianchi, M.D.

(2000) Protective effects of vitamin C against cisplatin-

induced nephrotoxicity and lipid peroxidation in adult

rats: A dose-dependent study. Pharmacological Research,

41, 405-411. doi:10.1006/phrs.1999.0600

[24] Chinery, R., Brockman, J.A., Peeler, M.O., Shyr, Y.,

Beauchamp, R.D. and Coffey, R.J. (1997) Antioxidants

enhance the cytotoxicity of chemotherapeutic agents in

colorectal cancer: A p53-independent induction of p21

WAF1/CIP1 via C/EBPbeta. Nature Medicine, 3, 1233-

1241.

[25] Daubeuf, S., Balin, D., Leroy, P. and Visvikis, A. (2003)

Different mechanisms for gamma-glutamyltranspepti-

dase-dependent resistance to carboplatin and cisplatin.

Biochemical Pharmacology, 66, 595-604.

[26] Agelaki, S., Tsatsanis, C., Gravanis, A. and Margioris,

A.N. (2002) Corticotropin-releasing hormone augments

proinflammatory cytokine production from macrophages

in vitro and in lipopolysaccharide-induced endotoxin

shock in. Infection and Immunity, 70, 6068-6074.

[27] Lovallo, W.R., Farag, N.H., Vincent, A.S., Thomas, T.L.

and Wilson, M.F. (2006) Cortisol responses to mental

stress, exercise, and meals following caffeine intake in

men and women. Pharmacology Biochemistry and Be-

haviour, 83, 441-447. doi:10.1016/j.pbb.2006.03.005

[28] Ruzic, B., Tomaskovic, I., Trnski, D., Kraus, O., Beka-

vac-Beslin, M. and Vrkic, N. (2005) Systemic stress re-

sponses in patients undergoing surgery for benign pro-

static hyperplasia. BJU International, 95, 77-80.

[29] Lutgendorf, SK., Weinrib, A.Z., Penedo, F., Russell, D.,

DeGeest, K. and Costanzo, E. (2008) Interleukin-6, cor-

tisol, and depressive symptoms in ovarian cancer patients.

Journal of Clinical Oncology, 26, 4820-4827.

doi:10.1200/JCO.2007.14.1978

[30] Young, A.H. (2004) Cortisol in mood disorders. St ress, 7,

205-208.

[31] Wang, L., Muxin, G., Nishida, H., Shirakawa, C., Sato, S.

and Konishi, T. (2007) Psychological stress-induced oxi-

dative stress as a model of sub-healthy condition and the

effect of TCM. Evidence Based Complementary and Al-

ternative Medicine, 4, 195-202.

[32] Marusin, A.V., Salyukov, V.B. and Yu Bragina, E. (2002)

Antioxidant activity of blood plasma in individuals with

neoplasms. Bulletin of Experimental Biology and Medi-

cine, 133, 481-483.

[33] Thakor, A.S. and Giussani, D.A. (2005) Antioxidants

enhance the adrenocortical response to stress in the fetus.

Endocrine Abstracts, 196th Meeting of the Society for

Endocrinology, London, UK, 7-9 November 2005, 10

OC22

[34] Erel, O.A. (2004) Novel automated method to measure

total antioxidant response against potent free radical re-

actions. Clinical Biochemistry, 37, 112-119.

[35] Perry, L.A. and Gossman, A.B. (1997) The role of the

laboratory in the diagnosis of Cushing’s syndrome. An-

nals of Clinical Biochemistry, 34, 345-359.

[36] Press, W.H., Teukolsky, S.A., Vetterling, W.T. and Flan-

nery B.P. (1992) Numerical Recipes in C: The art of sci-

entific computing. Cambridge University Press, Cam-

bridge.

[37] Almawi, W.Y. and Melemedjian, O.K. (2002) Negative

regulation of nuclear factor-kappab activation and func-

tion by glucocorticoids. Journal of Molecular Endocri-

nology, 28, 69-78. doi:10.1677/jme.0.0280069

[38] Marumo, T., Schini-Kerth, V.B., Brandes, R.P. and Busse,

R. (1998) Glucocorticoids inhibit superoxide anion pro-

duction and p22 phox mRNA expression in human aortic

smooth muscle cells. Hypertension, 32, 1083-1088.

[39] Pejić, S., Todorović, A., Stojiljković, V., Cvetković, D.,

Lucić, N., Radojicić, R.M., et al. (2008) Superoxide

dismutase and lipid hydroperoxides in blood and endo-

metrial tissue of patients with benign, hyperplastic and

malignant endometrium. Annals of the Brazilian Acad-

emy of Science, 80, 515-522.

E. Limberaki et al. / Health 3 (2011) 512- 517

517

[40] Swaab, D.F., Raadsheer, F.C., Endert, E., Hofman Kam-

phorst, M.W. and Ravid, R. (2006) Increased cortisol

levels in Aging and Alzheimer’s disease in postmortem

cerebrospinal fluid. Journal of Neuroendocrinology, 6,

681-687. doi:10.1111/j.1365-2826.1994.tb00635.x

[41] Morrow, G.R., Hickok, J.T., Andrews, P.L. and Stern,

R.M. (2002) Reduction in serum cortisol after platinum

based chemotherapy for cancer: A role for the HPA axis

in treatment-related nausea? Psychophysiology, 39, 491-

495. doi:10.1111/1469-8986.3940491

[42] Paris, J.J., Franco, C., Sodano, R., Freidenberg, B.,

Gordis, E., Anderson, D.A., et al. (2010) Sex differences

in salivary cortisol in response to acute stressors among

healthy participants, in recreational or pathological gam-

blers, and in those with posttraumatic stress disorder.

Hormones and Behaviour, 57, 35-45.

doi:10.1016/j.yhbeh.2009.06.003

[43] McCann, J. (2000) Gender differences in cancer that

don’t make sense—Or do they? Journal of the National

Cancer Institute, 92, 1560-1562.

doi:10.1093/jnci/92.19.1560