DRINKING BEHAVIOR AND c fos EXPRESSION IN RAT BRAIN INDUCED BY INTRACEREBROVENTRICULAR INJECTION OF HYPERTONIC SALINE AND SUCROSE

Drinking behavior and the distribution of c fos expression in the brain provoked by intracerebroventricular (icv)injection of hypertonic substances were studied in awaking Sprague Dawley rats. The results indicated that icv injection of 1 5 mol/L NaCl,3 mol/L NaCl or 3 mol/L sucrose could induce significant drinking response and Fos like immunoreactive(FLI) expression in organum vasculosum of laminae terminalis (OVLT),median preoptic nucleus (MPN) of forebrain, in supraoptic nucleus (SON) and paraventricular nucleus(PVN) of hypothalamus as well as in area postrema (AP),lateral parabrachial nucleus (LPBN) and solitary tract nucleus (STN) of hindbrain. No FLI expression was observed in subfornical organ (SFO). The induced FLI expression by hypertonic saline stimulation was stronger than that by sucrose solution with the same osmolarity.The FLI expression induced by 3 mol/L NaCl was more than that by 1 5 mol/L NaCl. As compared with previous studies, the present results indicated that except for SFO,the distribution of FLI expression in brain induced by central injection of hypertonic substances was similar to that induced by central injection of angiotensin II and peripheral injection of hypertonic substances.These results suggest that the central pathways underlying drinking response induced by different dipsogenic factors through different routes of administration are not the same.