RELATIONSHIP BETWEEN THE PRESENCE OF a7 NICOTINIC RECEPTOR AND APOPTOSIS OF HUMAN LYMPHOCYTES

ESANDI MC; DE ROSA MJ; GARELLI A; RAYES D; BOUZAT C

Bariloche, Río Negro, Argentina.

Congreso; XXXIX Reunión Nacional de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); XXXII Reunión Anual Sociedad Argentina de Biofísica (SAB); 2003

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB),Sociedad Argentina de Biofísica (SAB)

Acetylcholine (ACh) is well known as a neurotransmitter in both the central and peripheral nervous systems. ACh receptors (AChR) have been recently identified in extraneuronal cells such as those of the immune system. By using RT-PCR we have detected mRNA of a7 nicotinic receptor (AChR) in peripheral human lymphocytes after incubation with different concentrations of nicotine (10-100 ìM). To determine the role of a7 in lymphocytes,  we measured the degree of apoptosis in the presence of different nicotinic ligands. The degree of apoptosis was determined by DNA cleavage forming a ladder pattern and by evaluating nuclear condensation with DAPI staining. Lymphocytes pretreated with nicotine (10-100 ìM) were less susceptible to cortisol-induced apoptosis compared to untreated cells. The inhibition of apoptosis was concentration-dependent, reaching a value of 50% at 100 µM nicotine. Correlation between the presence of a7 mRNA and protection from apoptosis was always observed. Furthermore, apoptosis protection was also observed in the presence of the antagonist a-bungarotoxin. This effect might be due either to the ability of both, the antagonist and nicotine, to induce upregulation or to desensitize and block AChRs. Given that lymphocytes secrete ACh, our results suggest that these cells contain functional a7 receptors.