The participation of oxytocin in the abirritation of lateral habenular nucleus on normal adult rats.

This paper probes into the participation of different concentrations of oxytocin in the pain regulation of lateral habenular nucleus on normal adult rats. The detailed experiment steps are as follows: microinject 1.25, 2.5, and 5nmol of oxytocin to three adult rats׳ lateral habenular nucleus, and measure the hind paw withdrawal latency (HWL) after 5, 10, 15, 20, 30, 45 and 60min with hot plate and pressure plate test as the indicator of algesia. At the same time, another group of adult rats were injected with normal saline as a control to observe the participation of oxytocin in the pain regulation of lateral habenular nucleus. Through the oxytocin microinjection, the HWL of rats was significantly prolonged, compared with the control group. According to the experimental results, the HWL of thermo stimulation on the left paw of the rats between OT group and the control group (injected with normal saline) showed no difference (p>0.05) after a microinjection of 1.25nmol in LHb, while the HWL of thermo stimulation on the left paw of the rats showed significant difference (p<0.01; p<0.01) after a microinjection of 2.5 and 5nmol in LHb; The HWL of thermo stimulation on the right paw of the rats between OT group and the control group (injected with normal saline) showed significant difference, slight difference and significant difference (p<0.01; p<0.05; p<0.01) after a microinjection of 1.25, 2.5 and 5.0nmol in LHb; The HWL of mechanical stimulation both on the left paw of the rats after a microinjection of 2.5nmol and on the right paw of the rats after a microinjection of 5nmol showed significant differences (p<0.01; p<0.01), and all the rest showed extremely significant differences (p<0.001). This experiment shows that oxytocin has significant abirritational effect on the lateral habenular nucleus of adult rats, which is dose dependent, especially after OT was injected for 15min.