Effects of naloxone on neurohypophyseal peptide release by hypertonic stimulation in chicks.

The effects of opioid peptides on the osmotic release of neurohypophyseal hormones, arginine vasotocin (AVT) and mesotocin (MT), were determined in 2-day-old chicks. Experiment 1 examined the effect of a variety of doses of naloxone, an opioid antagonist, on chicks administered isotonic or hypertonic solution. Plasma osmolality in chicks administered hypertonic solution was significantly higher than that in groups administered isotonic solution. None of the doses of naloxone affected plasma osmolality in response to isotonic and hypertonic solution. Plasma levels of AVT increased in hypertonic solution and this response was further enhanced by naloxone injection as the doses increased. The hypertonic solution alone did not affect plasma levels of MT, but additional treatment with naloxone slightly increased plasma levels of MT. Experiment 2 examined the effect of DAMGO ([d-Ala(2), N-Me-Phe(4),Gly-ol]-enkepha lin), a specific mu receptor agonist. Relatively high plasma osmolality caused by hypertonic solution was not affected by additional treatment with DAMGO. Plasma levels of AVT in response to hypertonic solution and to additional treatment with naloxone were reduced by higher doses of DAMGO. Experiment 3 examined the effect of naloxone on chicks administered different concentrations of NaCl. Administration of hypertonic solution resulted in an increase in plasma osmolality and plasma levels of AVT. Naloxone administration enhanced the increase in plasma AVT levels in response to hypertonic solution. Experiment 4 examined the effect of naloxone on different kinds of hypertonic solution, 0.15 M NaCl, 1.5 M NaCl, 2.55 M urea, and 1.95 M sucrose. The increases in plasma osmolality resulting from the administration of the urea and sucrose solutions were the same as those in the chicks injected with 1.5 M NaCl. In sucrose-treated chicks, plasma levels of AVT increased in chicks administered naloxone but not in chicks injected with normal saline. In contrast, no significant changes in plasma levels of AVT were observed in urea treatment with or without naloxone. In Experiments 3 and 4, plasma levels of MT after administration of hypertonic solutions did not change. However, naloxone administration enhanced plasma levels of MT in osmotically stimulated chicks. The results of the present study suggest that opioid peptides attenuate the increase in plasma AVT and MT in hypertonic states.

[1]  A. Kastin,et al.  A potent and selective endogenous agonist for the µ-opiate receptor , 1997, Nature.

[2]  H. Minakata,et al.  Isolation and characterization of opioid peptides in the avian brain. , 1995, The Journal of experimental zoology.

[3]  S. Imai,et al.  An opiate receptor in the neurohypophysis of laying hens. , 1995, Poultry science.

[4]  B. Newton,et al.  An in situ hybridization and immunohistochemical study of vasotocin neurons in the hypothalamus of water-deprived chickens , 1994, Peptides.

[5]  P. Deviche,et al.  Identification, partial characterization, and hypothalamic distribution of κ, μ, and δ opioid receptors in a passerine songbird (Junco hyemalis) , 1993, Brain Research.

[6]  R. Acher.  Neurohypophysial peptide systems: processing machinery, hydroosmotic regulation, adaptation and evolution , 1993, Regulatory Peptides.

[7]  Rainer Martin,et al.  Methionine5-enkephalin and opiate binding sites in the neurohypophysis of the bird, Gallus domesticus , 1992, Regulatory Peptides.

[8]  A. Csillag,et al.  Distribution of mu, delta, and kappa opioid receptor binding sites in the brain of the one‐day‐old domestic chick (Gallus domesticus): An in vitro quantitative autoradiographic study , 1990, The Journal of comparative neurology.

[9]  J. Summy-Long,et al.  Kappa opiate receptors inhibit release of oxytocin from the magnocellular system during dehydration. , 1990, Neuroendocrinology.

[10]  G. Pasternak,et al.  Kappa opiate receptor multiplicity: evidence for two U50,488-sensitive kappa 1 subtypes and a novel kappa 3 subtype. , 1989, The Journal of pharmacology and experimental therapeutics.

[11]  D. Denbow,et al.  Ingestive responses to mu and delta opioid receptor agonists in the domestic fowl. , 1989, British poultry science.

[12]  R. Evans,et al.  μ‐ AND K‐OPIATE RECEPTOR AGONISTS REDUCE PLASMA NEUROHYPOPHYSIAL HORMONE CONCENTRATIONS IN WATER‐DEPRIVED AND NORMALLY HYDRATED RATS , 1989, Clinical and experimental pharmacology & physiology.

[13]  J. Haaf,et al.  Dynorphin-(1-13) is a potent in vivo suppressor of vasopressin levels in the rat. , 1987, Acta endocrinologica.

[14]  P. Rayford,et al.  An antiserum that recognizes mesotocin and isotocin: development of a homologous radioimmunoassay for plasma mesotocin in chickens (Gallus domesticus). , 1986, General and comparative endocrinology.

[15]  E. Braun,et al.  Regulation of plasma arginine vasotocin in conscious water-deprived domestic fowl. , 1986, The American journal of physiology.

[16]  D. de Wied,et al.  Effect of the opioid peptide beta-endorphin on the in vivo release of vasopressin in rats under various conditions. , 1986, Neuroendocrinology.

[17]  H. Kobayashi,et al.  Effects of Leu5-enkephalin on natural and angiotensin II-induced drinking in the Japanese quail (Coturnix coturnix japonica). , 1984, General and comparative endocrinology.

[18]  J. Summy-Long,et al.  A functional role for opioid peptides in the differential secretion of vasopressin and oxytocin , 1984, Brain Research.

[19]  H. Burton,et al.  Corticothalamic connections from the second somatosensory area and neighboring regions in the lateral sulcus of macaque monkeys , 1984, Brain Research.

[20]  R. Olson,et al.  Effects of naloxone and its quaternary form on fluid consumption in rats , 1982, Pharmacology Biochemistry and Behavior.

[21]  J. Fitzsimons.  The physiology of thirst and sodium appetite. , 1979, Monographs of the Physiological Society.

[22]  Joel L. Davis,et al.  Autoradiographic distribution of L-proline in chicks after intracerebral injection , 1979, Physiology & Behavior.

[23]  T. I. Koike,et al.  Effect of saline infusion on plasma immunoreactive vasotocin in conscious chickens (Gallus domesticus). , 1979, General and comparative endocrinology.

[24]  R. Acher,et al.  Phylogeny of the Neurohypophysial Hormones , 1967, Nature.