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2423 Activation of ascending pathways from the nucleus of the solitary tract to the subfornical organ by hemorrhage
S259 2421
INTIMATE RELATlONSHlP BETWEEN ENDOTHELINS AND CATECHOLAMINES THROUGH ET-A RECEPTOR. JUNZO OCHI, HISAO YAMADA, KIYOSHI KUROKAWA, Dept. of Anatomy, Shiga University of Medical Science, Otsu City, Shiga 520-2 I, Japan. Endothelin, a brain-vascular peptide, consists of three isopeptides (ET-l, ET-2 and ET-3) and has two types of receptors (ET-AR and ET-BR), Our previous immunohistochemical study showed that ET-AR exists in the catecholaminergic (CA) neurons in CNS, dopaminergic amacrine cells in retina, and postganglionic sympathetic nerve cells. To elucidate the relationship between ETs and CAs, we immunohistochemically analyzed rat adrenal medulla using antibodies to mature ETs, Big ET-I, Big ET-3 and ET-AR. The animals (Wistar rats weighing 180-250 grams) were sacrificed under anesthesia with sodium pentobarbital (50mgjkg b.wt., i.p.). Many nerve fibers containing Big ET-l were found in adrenal medulla, while no immunoreactivity for mature ETs and Big ET-3 is observed. Noradrenalin cells, which do not contain PNMT enzyme, were immunostained with ET-AR antibody. In these cells, Cat+ release from endogenous stores occurred by ET- 1 administration to primary culture of adrenal medulla in vitro . Because Big ET- 1 can be converted to mature ET-1 andC-peptideon the chromaffincell membrane,it is consideredthat Big ET-l isreleasedfrom preganglionic nerve fibers, and releasedBig ET- 1 is converted to matureET-I, which actson the noradrenalincells.
2422
RESPONSES OF MEDIAN PREOmlC NEURONSPROJECTINGTO THE HYPOTHALAMIC PARAVENTRICULAR NUCLEUSTO OSMOTIC STIMULATION IN WKY AND SHR. tSHIMAMUNE
b The response of median preoptic nucleus (MnPO) neurons antidromically identified as projecting to the hypothalamic paraventricular nucleus (PVN) to osmotic stimulation was investigated in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR), lo-, 15 and 20-weeks-old (WO), under urethane anesthesia. No significant differences in the latency, conduction velocity, or threshold of antidromic activation were observed between WKY and SHR. In each age, the spontaneous discharge rate was significantly higher in SHR than in WKY. Intracarotid injections of isotonic saline (0.15 M NaCl solution, 0.05 ml) did not cause the activity of almost all (98%) of the identified MnPO neurons. Similar injections of hypertonic saline (0.3 M NaCl solution, 0.05 ml) produced an excitation (6796, 62% and 65% in WKY; 58%, 57% and 65% in SHR; lo-, 15- and 20-WO, respectively) or an inhibition (14%, 12% and 13% in WKY; 1l%, 13% and 15% in SHR) in the excitability of idetified neurons. The duration and frequency of excitatory response, but not the inhibitory response, caused by the osmotic stimulation was much greater in 15- and 20-WO SHR than in lo-OW SHR and age-matched WKY. The data show that there is a difference between WKY and SHR in the responsivity of MnPO neurons projecting to the PVN to the osmotic stimulation and that, in SHR, these MnPO neurons undergo dramatic alterations with age in the responsivity. (Supportedin part by Grants05780602and 06780675from the Ministry of Education,Science and Culture, Japan, to J.T.)
2423
ACTIVATION OF ASCENDING PATHWAYS FROM THE NUCLEUS OF THE SOLITARY TRACT TO THE SUBFORNICALORGAN BY HEMORRHAGE. JUNICHI TANAKA’, YASUSHI HAYASHl*. IKUE MUGURUMA’. AKIHIKO USHIGOME’. SATORU SHIMAMUNE’. ‘Denartment of Human DeVelODment, *DeDartment of Education for HandicaoDed Children. Naruto Universitv of Education. Tokushima 772, laoan. Experiments were done to investigate whether the ascending pathways from the nucleus of the solitary tract (NTS) to the subfornical organ (SFO) are activated by hemorrhage in male rats under urethane anesthesia. (1) The activity of 27 NTS neurons that were antidromically identified by electrical stimulation of the SF0 was tested a response to hemorrhage (10 ml/kg, b.w.t.). Of the neurons tested, 19 displayed an increase and 3 exhibited a reduction in neuronal excitability in response to hemorrhage, while 5 were unresponsive. (2) Electrical stimulation of the NTS produced an excitation (n = 24) or an inhibition (n = 4) on the activity of neurons histologically confirmed in the SFO. Approximately two-thirds (n = 15) of SF0 neurons that demonstrated the excitation to NTS stimulation showed a facilitation in neuronal firing in response to hemorrhage, while the remaining excitatory (n = 9) and all the inhibitory (n = 4) neurons to NTS stimulation were unresponsive. These results suggest that NTS neurons projecting directly to the SF0 may be involved in the relaying cardiovascular afferent information to the SFO. (Supported
in part
by Grants
05780602
and 06780675
from
the Ministry
of Education,
Science
and Culture,
Japan,
to J.T.)
INTIMATE RELATlONSHlP BETWEEN ENDOTHELINS AND CATECHOLAMINES THROUGH ET-A RECEPTOR. JUNZO OCHI, HISAO YAMADA, KIYOSHI KUROKAWA, Dept. of Anatomy, Shiga University of Medical Science, Otsu City, Shiga 520-2 I, Japan. Endothelin, a brain-vascular peptide, consists of three isopeptides (ET-l, ET-2 and ET-3) and has two types of receptors (ET-AR and ET-BR), Our previous immunohistochemical study showed that ET-AR exists in the catecholaminergic (CA) neurons in CNS, dopaminergic amacrine cells in retina, and postganglionic sympathetic nerve cells. To elucidate the relationship between ETs and CAs, we immunohistochemically analyzed rat adrenal medulla using antibodies to mature ETs, Big ET-I, Big ET-3 and ET-AR. The animals (Wistar rats weighing 180-250 grams) were sacrificed under anesthesia with sodium pentobarbital (50mgjkg b.wt., i.p.). Many nerve fibers containing Big ET-l were found in adrenal medulla, while no immunoreactivity for mature ETs and Big ET-3 is observed. Noradrenalin cells, which do not contain PNMT enzyme, were immunostained with ET-AR antibody. In these cells, Cat+ release from endogenous stores occurred by ET- 1 administration to primary culture of adrenal medulla in vitro . Because Big ET- 1 can be converted to mature ET-1 andC-peptideon the chromaffincell membrane,it is consideredthat Big ET-l isreleasedfrom preganglionic nerve fibers, and releasedBig ET- 1 is converted to matureET-I, which actson the noradrenalincells.
2422
RESPONSES OF MEDIAN PREOmlC NEURONSPROJECTINGTO THE HYPOTHALAMIC PARAVENTRICULAR NUCLEUSTO OSMOTIC STIMULATION IN WKY AND SHR. tSHIMAMUNE
b The response of median preoptic nucleus (MnPO) neurons antidromically identified as projecting to the hypothalamic paraventricular nucleus (PVN) to osmotic stimulation was investigated in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR), lo-, 15 and 20-weeks-old (WO), under urethane anesthesia. No significant differences in the latency, conduction velocity, or threshold of antidromic activation were observed between WKY and SHR. In each age, the spontaneous discharge rate was significantly higher in SHR than in WKY. Intracarotid injections of isotonic saline (0.15 M NaCl solution, 0.05 ml) did not cause the activity of almost all (98%) of the identified MnPO neurons. Similar injections of hypertonic saline (0.3 M NaCl solution, 0.05 ml) produced an excitation (6796, 62% and 65% in WKY; 58%, 57% and 65% in SHR; lo-, 15- and 20-WO, respectively) or an inhibition (14%, 12% and 13% in WKY; 1l%, 13% and 15% in SHR) in the excitability of idetified neurons. The duration and frequency of excitatory response, but not the inhibitory response, caused by the osmotic stimulation was much greater in 15- and 20-WO SHR than in lo-OW SHR and age-matched WKY. The data show that there is a difference between WKY and SHR in the responsivity of MnPO neurons projecting to the PVN to the osmotic stimulation and that, in SHR, these MnPO neurons undergo dramatic alterations with age in the responsivity. (Supportedin part by Grants05780602and 06780675from the Ministry of Education,Science and Culture, Japan, to J.T.)
2423
ACTIVATION OF ASCENDING PATHWAYS FROM THE NUCLEUS OF THE SOLITARY TRACT TO THE SUBFORNICALORGAN BY HEMORRHAGE. JUNICHI TANAKA’, YASUSHI HAYASHl*. IKUE MUGURUMA’. AKIHIKO USHIGOME’. SATORU SHIMAMUNE’. ‘Denartment of Human DeVelODment, *DeDartment of Education for HandicaoDed Children. Naruto Universitv of Education. Tokushima 772, laoan. Experiments were done to investigate whether the ascending pathways from the nucleus of the solitary tract (NTS) to the subfornical organ (SFO) are activated by hemorrhage in male rats under urethane anesthesia. (1) The activity of 27 NTS neurons that were antidromically identified by electrical stimulation of the SF0 was tested a response to hemorrhage (10 ml/kg, b.w.t.). Of the neurons tested, 19 displayed an increase and 3 exhibited a reduction in neuronal excitability in response to hemorrhage, while 5 were unresponsive. (2) Electrical stimulation of the NTS produced an excitation (n = 24) or an inhibition (n = 4) on the activity of neurons histologically confirmed in the SFO. Approximately two-thirds (n = 15) of SF0 neurons that demonstrated the excitation to NTS stimulation showed a facilitation in neuronal firing in response to hemorrhage, while the remaining excitatory (n = 9) and all the inhibitory (n = 4) neurons to NTS stimulation were unresponsive. These results suggest that NTS neurons projecting directly to the SF0 may be involved in the relaying cardiovascular afferent information to the SFO. (Supported
in part
by Grants
05780602
and 06780675
from
the Ministry
of Education,
Science
and Culture,
Japan,
to J.T.)