STRESS zyxwv MEDICINE. VOL. zyxw 12: zyx 55-63 (1996) THE INFLUENCE OF ACCULTURATION ON ENDOCRINE REACTIVITY DURING ACUTE STRESS IN URBAN BLACK MALES N. T. MALAN. DSc. J zyxwvutsrqp S. BRITS. MSc. F. C. ELOFF. DSc. H W. HUISMAN. MSc. A KRUGER. MSocSc. P J LAUBSCHER, MSc AND P. J. PRETORIUS. DSc zyxwvu Depcrrtt?icwt zyxwvutsrq of' Plij~siologj~. Po/chyf~/room Lftiivrrsitj.. Potc.licf.~trooni, zyxw Soirtli .4fiic~r H. S. STEYN. DSc Stati.rtic,cil Coti.viilititioti Servir~es. Potchef:itroom Utzivc~r.si/j~. Potc,hc.f.~tr-ooni. Soiith .4/iic,rr SUMMARY Urbanization is a world-wide phenomenon and results in a radical and sometimes total change in living conditions. This process is accompanied by a significant increase in the incidence of western-type diseases virtually unknown in traditional rural communities. Especially in a multicultural society like South Africa, rural people moving to the city will experience cultural shock leading in many cases to a large degree of acculturation. In this study the effect of acculturation on endocrine reactivity was studied in a population of Tswanas. It was found that significant differences in endocrine reactivity exist not only between rural Tswanas and urban whites but in some instances also between rural Tswanas and urban Tswanas. During the cold pressor test, the testosterone reactivity and to a lesser extent the prolactin reactivity of the urban Tswanas tended to approach that of the white group as a function of their level of acculturation. All the Tswana groups had a significantly higher plasma renin activity during acute stress than the whites, which could have a bearing on the tendency of urban blacks to develop hypertension. KEY WORDS-urbanization; rural; race; western-type diseases; hormone; cortisol: testosterone; prolactin; renin activity; hypertension Urbanization is a world-wide phenomenon and, especially in the developing world. is currently the cause of a massive population shift.' zyxwvut ' A striking phenomenon during this process of urbanization is the change in the pattern of causes of death that occurs in urbanizing communities.' In traditional rural communities the incidence of so-called western-type diseases like hypertension, coronary heart disease and diabetes IS virtually ~ n k n o w n . ~ However. in urban. acculturated communities all over the world it seems that these individuals are much more vulnerable to these diseases than even those who have lived their entire lives in an urban environment.'." Moving from the rural area to the urban environment involves a changeover from a system of cultural uniformity to an unfamiliar, disrupted environment. In this uncertain environ- ment the individual may find it difficult to uphold Address for correspondence: Dr N. T. Malan. Department of Physiology. Potchefstroom University. Potchefstroom 2520, South Africa. Tel: South Africa (0148) 992436. Fax: South Africa (0148) 992799. CCC 0748-8386/96/0 10055XY e 1996 by John Wile? & Son>. Ltd his traditional way of life and, in order to survive, may feel the need to abandon his traditional cultural beliefs. In this process of acculturation the social support he experienced in the traditional rural setting'? will disappear, contributing to the uncertainty of his urban existence. In an effort to elucidate some aspects of the physiological changes brought about by stresses associated with urbanization and the resulting acculturation, this study was launched to compare endocrine reactivity in three groups of blacks from the Tswana tribe in different states of accultura- tion, while a group of urban whites was included in the study as a reference group. In this context endocrine reactivity means the changes in the plasma level of a specific hormone under the influence of acute stress. According to Mason," Henry,I4 Henry et d.I5 and others, endocrine reaction patterns give a good indication of the severity as well as the type of stress experienced by an individual. The reaction patterns of cortisol, testosterone and prolactin (PRL) as well as the activity of the enzyme renin. as an indirect