Intracisternally Injected L-Proline Activates Hypothalamic Supraoptic, but Not Paraventricular, Vasopressin-Expressing Neurons in Conscious Rats

When injected into specific rat brain regions, the neurotransmitter candidate L-proline produces various cardiovascular changes through ionotropic excitatory amino acid receptors. The present study used an immunohistochemical double-labeling approach to determine whether intracisternally injected L-proline in freely moving rats, which increases blood pressure, activates hypothalamic vasopressin-expressing neurons and ventral medullary tyrosine-hydroxylase- (TH-) containing neurons. Following injection of L-proline, the number of activated hypothalamic neurons that coexpressed vasopressin and c-Fos was much greater in the supraoptic nucleus (SON) than in the paraventricular nucleus (PVN) of rats with increased blood pressure. The number of activated TH-containing neurons was significantly greater following L-proline treatment than following control injections of artificial cerebrospinal fluid (ACSF). These results clearly demonstrate that intracisternally injected L-proline activates hypothalamic supraoptic, but not paraventricular, vasopressin-expressing neurons and medullary TH-containing (A1/C1) neurons in freely moving rats.

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Effect of L-glutamate injected into the hypothalamus on blood pressure and heart rate in freely moving rats

The Japanese Journal of Pharmacology ◽

10.1016/s0021-5198(19)54232-9 ◽

1982 ◽

Vol 32 ◽

pp. 268

Author(s):

Shizuo Nakamura ◽

Hisashi Ohta ◽

Shigenori Watanabe ◽

Showa Ueki

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Freely Moving Rats ◽

Freely Moving

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Ionotropic excitatory amino acid receptors in discrete brain regions of kindled rats

Brain Research ◽

10.1016/0006-8993(92)91429-i ◽

1992 ◽

Vol 587 (1) ◽

pp. 73-82 ◽

Cited By ~ 16

Author(s):

Kazufumi Akiyama ◽

Yukio Yoneda ◽

Kiyokazu Ogita ◽

Takashi Itoh ◽

Akihiro Daigen ◽

...

Keyword(s):

Amino Acid ◽

Excitatory Amino Acid ◽

Brain Regions ◽

Excitatory Amino Acid Receptors ◽

Amino Acid Receptors

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Postnatal Changes in Local Cerebral Blood Flow Measured by the Quantitative Autoradiographic [14C]Iodoantipyrine Technique in Freely Moving Rats

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1989.83 ◽

1989 ◽

Vol 9 (5) ◽

pp. 579-588 ◽

Cited By ~ 73

Author(s):

Astrid Nehlig ◽

Anne Pereira de Vasconcelos ◽

Sylvette Boyet

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Glucose Utilization ◽

Brain Regions ◽

Postnatal Period ◽

High Rate ◽

Local Cerebral Blood Flow ◽

Adult Rat ◽

Freely Moving Rats ◽

Freely Moving

The postnatal changes in local cerebral blood flow in freely moving rats were measured by means of the quantitative autoradiographic [14C]iodoantipyrine method. The animals were studied at 10, 14, 17, 21, and 35 days and at the adult stage. At 10 days after birth, rates of blood flow were very low and quite homogeneous in most cerebral structures except in a few posterior areas. From these relatively uniform levels, values of local cerebral blood flow rose notably to reach a peak at 17 days in all brain regions studied. Rates of blood flow decreased between 17 and 21 days after birth and then increased from weaning time to reach the known characteristic distribution of the adult rat. The postnatal evolution of local cerebral blood flow in the rat is in good agreement with previous studies in other species such as dog and humans that also show higher rates of cerebral blood flow and glucose utilization at immature stages. However, in the rat, local cerebral blood flow and local cerebral glucose utilization are not coupled over the whole postnatal period studied, since blood flow rates reach peak values at 17 days whereas glucose utilization remains still quite low at that stage. The high rate of cerebral blood flow in the 17-day-old rat may reflect the energetic and biosynthetic needs of the actively developing brain that are completed by the summation of glucose and ketone body utilization.

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Osmotic stimulation of vasopressin mRNA content in the supraoptic nucleus requires synaptic activation

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.268.4.r1034 ◽

1995 ◽

Vol 268 (4) ◽

pp. R1034-R1039 ◽

Cited By ~ 3

Author(s):

C. D. Sladek ◽

K. Y. Fisher ◽

H. E. Sidorowicz ◽

J. R. Mathiasen

Keyword(s):

Synaptic Input ◽

Supraoptic Nucleus ◽

Kynurenic Acid ◽

Excitatory Amino Acid ◽

Vasopressin Release ◽

Amino Acid Receptors ◽

Mrna Content ◽

Supraoptic Neurons ◽

Vasopressin Neurons

The role of synaptic input to the vasopressin neurons in hypertonicity-induced increase in vasopressin mRNA content was evaluated. Synaptic connection with the anterior hypothalamus is required for hypertonicity to increase vasopressin release. However, the potential for other mechanisms to induce the increase in vasopressin mRNA content is suggested by the fact that hypertonicity induces depolarization of supraoptic neurons independently of synaptic input. Explants of the hypothalamoneurohypophysial system were used to study the effect of depolarization and hypertonicity in the presence and absence of nonspecific synaptic blockade by 15 mM MgSO4 or blockade of excitatory amino acid receptors with kynurenic acid. Vasopressin release and mRNA content were increased by depolarization with 40 mM KCl and by exposure to hypertonicity (P < 0.05). Basal and osmotically stimulated vasopressin release was decreased by MgSO4 and by kynurenic acid. Both agents prevented the hypertonicity-induced increase in vasopressin mRNA content. Thus either synaptic input or increased VP release is required for hypertonicity to increase vasopressin mRNA, and excitatory amino acids are implicated in this response.

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Electrophysiological evidence for excitatory amino acid receptors in the rat supraoptic nucleus in vitro

Neuroscience Letters ◽

10.1016/0304-3940(91)90628-7 ◽

1991 ◽

Vol 131 (2) ◽

pp. 260-262 ◽

Cited By ~ 18

Author(s):

Valentin K. Gribkoff

Keyword(s):

Amino Acid ◽

Supraoptic Nucleus ◽

Excitatory Amino Acid ◽

Excitatory Amino Acid Receptors ◽

Amino Acid Receptors ◽

Electrophysiological Evidence

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Fos expression following isotonic volume expansion of the unanesthetized male rat

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1998.274.5.r1345 ◽

1998 ◽

Vol 274 (5) ◽

pp. R1345-R1352 ◽

Cited By ~ 18

Author(s):

R. R. Randolph ◽

Q. Li ◽

K. S. Curtis ◽

M. J. Sullivan ◽

J. T. Cunningham

Keyword(s):

Volume Expansion ◽

Supraoptic Nucleus ◽

Venous Pressure ◽

Isotonic Saline ◽

Brain Regions ◽

Ventrolateral Medulla ◽

Male Rat ◽

Double Labeling ◽

Vasopressin Release ◽

Fos Expression

Cardiopulmonary afferents, baroreceptor afferents, or atrial natriuretic peptide binding to circumventricular organs may mediate the central response to volume expansion, a condition common to pregnancy, exercise training, and congestive heart failure. This study used Fos immunocytochemistry to examine brain regions activated by volume expansion. Male Sprague-Dawley rats were infused with isotonic saline equal to 10% of their body weight in 10 min followed by a maintenance infusion of 0.5 ml/min for 110 min. Control animals received 2-h infusions at 0.01 ml/min. Five minutes after the start of volume expansion, central venous pressure of expanded animals was significantly greater than control animals. The volume-expanded group exhibited significantly greater Fos activation ( P < 0.05) in the area postrema, nucleus of the solitary tract, caudal ventrolateral medulla, paraventricular nucleus, supraoptic nucleus, and perinuclear zone of the supraoptic nucleus. Double labeling indicates that oxytocinergic neurons in the supraoptic nucleus are activated. Neurons in brain regions known to inhibit both sympathetic activity and vasopressin release show increased Fos expression following isotonic volume expansion.

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Osmotic stimulation of the supraoptic nucleus: central and peripheral vasopressin release and blood pressure

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1994.266.3.e351 ◽

1994 ◽

Vol 266 (3) ◽

pp. E351-E356 ◽

Cited By ~ 3

Author(s):

M. Ludwig ◽

T. Horn ◽

M. F. Callahan ◽

A. Grosche ◽

M. Morris ◽

...

Keyword(s):

Blood Pressure ◽

Arterial Pressure ◽

Supraoptic Nucleus ◽

Pressor Response ◽

Extracellular Fluid ◽

Brain Regions ◽

Vasopressin Release ◽

Peptide Release ◽

Osmotic Stimulation ◽

Stimulation Of

Experiments were performed to determine the effect of direct osmotic stimulation of the supraoptic nucleus (SON) on central and peripheral vasopressin (AVP) release and arterial pressure. A microdialysis method was used to deliver hyperosmotic NaCl, mannitol or urea bilaterally into the SON and to sample SON extracellular fluid and blood. Simultaneous brain and blood microdialysis showed that hyperosmotic NaCl increased central and peripheral AVP release and increased mean arterial pressure (MAP). The pressor response was not blocked by intravenous injection of a V1-receptor antagonist, D(CH2)5Tyr(Me)AVP, suggesting that circulating AVP was not involved in that response. Hyperosmotic mannitol or urea caused an increase in central peptide release, but failed to affect MAP or peripheral AVP release. The results suggest that central AVP release within the SON may be due to osmoreceptor stimulation while the peripheral effects on AVP release and MAP are specific for sodium. The results also demonstrate the utility of brain and blood microdialysis for the delivery of stimuli into specific brain regions with simultaneous monitoring of central and peripheral peptide release.

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