Reversible inactivation and excitation of nucleus raphe magnus can modulate tail blood flow of male wistar rats in response to hypothermia

The nucleus raphe magnus [NRM] is involved in thermoregulatory processing. There is a correlation between changes in the firing rates of the cells in the NRM and the application of the peripheral thermal stimulus. We examined the effect of reversible inactivation and excitation of NRM on mechanisms involved in tail blood flow [TBF] regulation in hypothermia. Hypothermia was induced in Male Wistar rats and cannula was implanted above the NRM. To evaluate the effect of nucleus inactivation on TBF, the amount of TBF was measured by Laser Doppler in hypothermic rats, before and after lidocaine microinjection into NRM. TBF was also measured after glutamate microinjection to assess the effect of nucleus excitation in hypothermic rats. Results indicated that after dropping TBF by hypothermia, microinjection of lidocaine into NRM significantly decreased TBF from 54.43 +/- 5.7 to 46.81 +/- 3.4, whereas glutamate microinjection caused a significant increase from 44.194 +/- 0.6 to 98 +/- 10.0 Conclusion: These data suggest that NRM have thermoregulatory effect in response to hypothermia

effect of nucleus tractus solitarius nitric oxidergic neurons on blood pressure in diabetic rats

It has been shown that nitric oxide is synthesized in the central nervous system as well as in vascular endothelial cells. Recently, it was reported that nitric oxide was involved in central cardiovascular regulation, baroreflex modulation, and involved in a reciprocal release with excitatory amino acids in the nucleus tractus solitarii of rats. The purpose of the present study was to investigate the possible interaction of nitric oxide and glucose in the nucleus tractus solitarii on blood pressure regulation. Male Wistar stereptozotocin induced diabetic rats were anesthetized with urethane. A cannula was inserted above the nucleus tractus solitarii and blood pressure was monitored intra-arterially. Unilateral microinjection of L-glutamate [2.3 nmol/60 nL] into the nucleus produced a decrease in blood pressure in diabetic rats. Microinjection of lidocaine [0.5 Mul%2] increased blood pressure. Unilateral microinjection of sodium nitroprusside [100 mmoV6O nL] into the nucleus increased blood pressure in diabetic rats. After microinjection of sodium nitroprusside, the depressive responses to glutamate were significantly attenuated. These results demonstrated the probable role of glucose on blood pressure regulation in diabetic animals affecting on nitric oxidergic neurons and so it implicates an interaction between nitric oxide and glucose in central cardiovascular regulation

[ effect of hyperglycmia on nitric oxidergic neurons in nucleus tractus solitarius and blood pressure regulation in rats with induced diabetes]

The role of nucleus tractus solitarius in cardiovascular system regulation is controversial. On the other hand, study on the problem of hypertension in diabetic animals is the subject of many research programs. The aim of the present study was to determine wheather inactivation of nucleus can affect blood pressure in diabetic rats. To this end, stereptosotocin-induced diabetic rats were anesthetized with Urethane and a cannula was inserted above nucleus. Blood pressure and heart rate were monitored using an intraarterial cannula. The cannulas were filled with L-glutamate [78 pmol/60 nL, to functionally identify the NTS; see below], L-NAME[1nmol, to inhibit the nitric oxidergic neurons] and sodium nitroprusside [100mmol,as a NO-donor]. The results indicated that inactivation of nucleus in diabetic rats, had no effect on systolic and mean arterial pressure but enhanced diastolic blood pressure [P<0.05]. There was no significant difference in heart rate between control and test groups. Glucose affect on increasing blood pressure in rats with induced diabetes, in part, is caused by nitric oxidergic neurons resided in neucleus tractus solitarius