The role of serotonergic 5-HT1A receptors in central cardiovascular regulation in haemorrhagic shock in rats.

The bleeding and haemorrhage is strictly related with accidents and many medical procedures. In some conditions it leads to hypovolaemia and further to hypovolaemic shock. Under conditions of haemorrhagic shock, heart rate and blood pressure critically collapse. Reversing the sympathoinhibitory phase of hypovolaemia could be crucial for clinical management of injured patients after haemorrhage. Systemic administration of 5-HT1A agonists seams to produce resuscitating effects. The aim of this study was to investigate the participation of central serotonin and, in particular, 5-HT1A receptors in cardiovascular regulation in haemorrhagic shock in rats. Intracerebroventricular (i.c.v.) administration of serotonin (5-HT) increased the heart rate (HR), mean arterial pressure (MAP) and implicated that all haemorrhaged animals survived for the whole observation time (2 hours). Similar, although significantly more minor, effects were achieved after selective 5-HT1A activation. Moreover, the i.c.v. administration of selective 5-HT1A antagonist before i.c.v. 5-HT injection partially inhibited 5-HT induced changes. The results of the present work indicate that 5-HT plays an important role in the reversal of the haemorrhagic shock in rats. These effects are at least partially dependent on activation of 5-HT1A receptors.