Intravenous 6-hydroxydopamine attenuates vasopressin and oxytocin secretion stimulated by hemorrhage and hypotension but not hyperosmolality in rats

Sean D. Stocker, Melinda E. Wilson, Christopher J. Madden, Usman Lone, Alan F. Sved

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The present study sought to determine whether chemical destruction of peripheral catecholaminergic fibers with 6-hydroxydopamine (6OHDA) attenuates vasopressin (VP) and oxytocin (OT) secretion stimulated by hemorrhage, hypotension, and hyperosmolality. Rats received 6OHDA (100 mg/kg iv) or vehicle (1 ml/kg iv) on days 1 and 7, and experiments were performed on day 8. Serial hemorrhage (4 samples of 2 ml per 300 g body wt at 10-min intervals) increased plasma VP and OT levels in both groups; however, the increase in plasma VP and OT levels was significantly attenuated in 6OHDA-treated vs. control rats despite a significantly lower mean arterial blood pressure. Similarly, the increase in plasma VP and OT levels in response to hypotension produced by the selective arteriolar vasodilator diazoxide was significantly attenuated in 6OHDA-treated rats. In marked contrast to hemorrhage and hypotension, hyperosmolality produced by an infusion of 1 M NaCl (2 ml/h iv) stimulated increases in plasma VP and OT levels that were not different between 6OHDA-treated and control rats. In a parallel set of experiments, intravenous 6OHDA treatment reduced dopamine-β-hydroxylase immunoreactivity in the posterior pituitary but had no substantial effect in the hypothalamic paraventricular and supraoptic nuclei. In each experiment, the pressor response to tyramine (250 μg/kg iv) was significantly attenuated in 6OHDA-treated rats, thereby confirming that 6OHDA treatment destroyed sympathetic catecholaminergic fibers. Collectively, these findings suggest that catecholaminergic fibers located outside the blood-brain barrier contribute to VP and OT secretion during hemorrhage and arterial hypotension.

Original languageEnglish (US)
Pages (from-to)R59-R67
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume291
Issue number1
DOIs
StatePublished - Jul 12 2006

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Oxidopamine
Oxytocin
Vasopressins
Hypotension
Hemorrhage
Arterial Pressure
Adrenergic Fibers
Diazoxide
Supraoptic Nucleus
Tyramine
Paraventricular Hypothalamic Nucleus
Mixed Function Oxygenases
Blood-Brain Barrier
Vasodilator Agents
Dopamine

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)

Cite this

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title = "Intravenous 6-hydroxydopamine attenuates vasopressin and oxytocin secretion stimulated by hemorrhage and hypotension but not hyperosmolality in rats",
abstract = "The present study sought to determine whether chemical destruction of peripheral catecholaminergic fibers with 6-hydroxydopamine (6OHDA) attenuates vasopressin (VP) and oxytocin (OT) secretion stimulated by hemorrhage, hypotension, and hyperosmolality. Rats received 6OHDA (100 mg/kg iv) or vehicle (1 ml/kg iv) on days 1 and 7, and experiments were performed on day 8. Serial hemorrhage (4 samples of 2 ml per 300 g body wt at 10-min intervals) increased plasma VP and OT levels in both groups; however, the increase in plasma VP and OT levels was significantly attenuated in 6OHDA-treated vs. control rats despite a significantly lower mean arterial blood pressure. Similarly, the increase in plasma VP and OT levels in response to hypotension produced by the selective arteriolar vasodilator diazoxide was significantly attenuated in 6OHDA-treated rats. In marked contrast to hemorrhage and hypotension, hyperosmolality produced by an infusion of 1 M NaCl (2 ml/h iv) stimulated increases in plasma VP and OT levels that were not different between 6OHDA-treated and control rats. In a parallel set of experiments, intravenous 6OHDA treatment reduced dopamine-β-hydroxylase immunoreactivity in the posterior pituitary but had no substantial effect in the hypothalamic paraventricular and supraoptic nuclei. In each experiment, the pressor response to tyramine (250 μg/kg iv) was significantly attenuated in 6OHDA-treated rats, thereby confirming that 6OHDA treatment destroyed sympathetic catecholaminergic fibers. Collectively, these findings suggest that catecholaminergic fibers located outside the blood-brain barrier contribute to VP and OT secretion during hemorrhage and arterial hypotension.",
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Intravenous 6-hydroxydopamine attenuates vasopressin and oxytocin secretion stimulated by hemorrhage and hypotension but not hyperosmolality in rats. / Stocker, Sean D.; Wilson, Melinda E.; Madden, Christopher J.; Lone, Usman; Sved, Alan F.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 291, No. 1, 12.07.2006, p. R59-R67.

Research output: Contribution to journalArticle

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T1 - Intravenous 6-hydroxydopamine attenuates vasopressin and oxytocin secretion stimulated by hemorrhage and hypotension but not hyperosmolality in rats

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AU - Wilson, Melinda E.

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N2 - The present study sought to determine whether chemical destruction of peripheral catecholaminergic fibers with 6-hydroxydopamine (6OHDA) attenuates vasopressin (VP) and oxytocin (OT) secretion stimulated by hemorrhage, hypotension, and hyperosmolality. Rats received 6OHDA (100 mg/kg iv) or vehicle (1 ml/kg iv) on days 1 and 7, and experiments were performed on day 8. Serial hemorrhage (4 samples of 2 ml per 300 g body wt at 10-min intervals) increased plasma VP and OT levels in both groups; however, the increase in plasma VP and OT levels was significantly attenuated in 6OHDA-treated vs. control rats despite a significantly lower mean arterial blood pressure. Similarly, the increase in plasma VP and OT levels in response to hypotension produced by the selective arteriolar vasodilator diazoxide was significantly attenuated in 6OHDA-treated rats. In marked contrast to hemorrhage and hypotension, hyperosmolality produced by an infusion of 1 M NaCl (2 ml/h iv) stimulated increases in plasma VP and OT levels that were not different between 6OHDA-treated and control rats. In a parallel set of experiments, intravenous 6OHDA treatment reduced dopamine-β-hydroxylase immunoreactivity in the posterior pituitary but had no substantial effect in the hypothalamic paraventricular and supraoptic nuclei. In each experiment, the pressor response to tyramine (250 μg/kg iv) was significantly attenuated in 6OHDA-treated rats, thereby confirming that 6OHDA treatment destroyed sympathetic catecholaminergic fibers. Collectively, these findings suggest that catecholaminergic fibers located outside the blood-brain barrier contribute to VP and OT secretion during hemorrhage and arterial hypotension.

AB - The present study sought to determine whether chemical destruction of peripheral catecholaminergic fibers with 6-hydroxydopamine (6OHDA) attenuates vasopressin (VP) and oxytocin (OT) secretion stimulated by hemorrhage, hypotension, and hyperosmolality. Rats received 6OHDA (100 mg/kg iv) or vehicle (1 ml/kg iv) on days 1 and 7, and experiments were performed on day 8. Serial hemorrhage (4 samples of 2 ml per 300 g body wt at 10-min intervals) increased plasma VP and OT levels in both groups; however, the increase in plasma VP and OT levels was significantly attenuated in 6OHDA-treated vs. control rats despite a significantly lower mean arterial blood pressure. Similarly, the increase in plasma VP and OT levels in response to hypotension produced by the selective arteriolar vasodilator diazoxide was significantly attenuated in 6OHDA-treated rats. In marked contrast to hemorrhage and hypotension, hyperosmolality produced by an infusion of 1 M NaCl (2 ml/h iv) stimulated increases in plasma VP and OT levels that were not different between 6OHDA-treated and control rats. In a parallel set of experiments, intravenous 6OHDA treatment reduced dopamine-β-hydroxylase immunoreactivity in the posterior pituitary but had no substantial effect in the hypothalamic paraventricular and supraoptic nuclei. In each experiment, the pressor response to tyramine (250 μg/kg iv) was significantly attenuated in 6OHDA-treated rats, thereby confirming that 6OHDA treatment destroyed sympathetic catecholaminergic fibers. Collectively, these findings suggest that catecholaminergic fibers located outside the blood-brain barrier contribute to VP and OT secretion during hemorrhage and arterial hypotension.

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