INTERACTIONS OF DRUGS WITH RESPONSES TO STRESSFUL STIMULI

MAURICIO R ODIO, Purdue University

Abstract

The main objective of this research was twofold. First, an attempt was made to determine if the response of plasma corticosterone (PCS), plasma free fatty acids (PFA), and plasma glucose (PGL) in rats, to a variety of stressful stimuli is a stressor-dependent (specific) or independent (non-specific) phenomenon. Second, by using suitable drugs, efforts have also been made to elucidate the relative involvement of individual neurotransmitter systems in the response of the plasma parameters measured to stressful stimuli. The stressors selected were physical immobilization (IMM), exposure to a 4(DEGREES)C environment (CLD) and unpredictable electric foot shock (ESK). These stimuli differ among themselves in terms of whether they are continuously (IMM, CLD) or discontinuously (ESK) applied, as well as, by whether the challenge they place upon the organism is a predominantly psychological (IMM, ESK) or a mainly physiological (CLD) one. Groups of drug-naive rats were exposed to the stressors for varying lengths of time. Other groups of animals were given various drugs prior to, as well as, during exposure to the stressors. The responses of PCS, PFA, and PGL to the three stressors were measured in the presence or absence of drugs throughout a 4 hour exposure to the stimuli used as well as at varying times following a 4 hour exposure to IMM, CLD, or ESK. The results obtained suggest the PCS and PFA responses to be stimulus-specific primarily as a function of whether the stressors are continuously or discontinuously applied; the PGL response similarly demonstrates stimulus-specificity primarily to psychological or physiological stimuli. The pharmacologically derived evidence supports the contention that the response to stress is a stimulus-dependent phenomenon. These studies however suggest that the specificity of response of these three plasma parameters is determined not necessarily by the stimulus itself but rather by whether the stressor falls within broader categorizations such as continuity or discontinuity, or, by whether it is predominantly physiological or psychological in nature.

Degree

Ph.D.

Subject Area

Pharmacology

COinS