Dopamine stimulates somatostatin release from perifused hypothalamic cells

Richardson, Stephen B.; Nguyen, Tam; Hollander, Charles S.

doi:10.1152/ajpendo.1983.244.6.e560

Cited by 13 publications

(9 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although influences of DA at other brain levels or on hypothalamic GRF cannot be ruled out, results of the lesioning experiment in the pres ent study suggest that DA stimulates GH secretion by in hibiting the release and/or synthesis of somatostatin-like GH release-inhibitory factor located in the preoptic area of the goldfish brain. These results in goldfish are in contrast to observations in the rat where DA has been shown to stimulate in vivo somatostatin release into hypophyseal portal blood [10] and from perifused hypothalamic cells in vitro [41], Further studies concerning the relationship of DA to hypothalamic somatostatin content and release are currently being conducted in our laboratory.…”

Section: Discussioncontrasting

confidence: 86%

Influences of Catecholamines on Growth Hormone Release in Female Goldfish, Carassius auratus

Chang¹,

Marchant²,

Cook³

et al. 1985

Neuroendocrinology

View full text Add to dashboard Cite

The influence of catecholamines on growth hormone (GH) release in female goldfish was investigated by monitoring serum GH levels following injections of drugs known to alter catecholamine synthesis and neural activities. Intraperitoneal (i.p.) injection of 6-tydroxydopamine, a catecholaminergic neurotoxin, or α-methyl-p-tyrosine, a catecholamine synthesis inhibitor, decreased serum GH levels. Intraperitoneal injection of L-β-dihydroxyphenylalanine (L-dopa) increased serum GH concentrations in a dose-dependent manner. The L-dopa-induced increase in serum GH was potentiated by i.p. injection of carbidopa, which would increase the availability of L-dopa to brain tissues by blocking the peripheral conversion of L-dopa to dopamine (DA). These results suggest that L-dopa or one of its catecholamine metabolites acts centrally to increase GH release. Intraventricular (i.v.t.) injection of DA and i.p. injection of apomorphine, a DA agonist that crosses the blood-brain barrier, increased serum GH. Intraperitoneal injection of DA did not alter circulating GH levels in normal fish or fish bearing preoptic lesions that abolish an inhibitory hypothalamic influence on GH release; however, DA increased serum GH in fish which had their blood-brain barrier destroyed by sham operation procedures. These results indicate that DA acts centrally to stimulate GH secretion, possibly by inhibiting the release and/or synthesis of GH release-inhibitory factor. Serum GH concentrations were decreased in a dose-dependent manner by i.p. injection of norepinephrine (NE), whereas i.v.t. injection of NE did not alter serum GH levels. These results indicate that NE acts outside of the blood-brain barrier to decrease serum GH levels in the goldfish, possibly by directly influencing pituitary GH cells. Preliminary data suggest that an α-adrenergic mechanism stimulating GH release in the goldfish may also be present, although the level of this action is not known.

show abstract

Section: Discussioncontrasting

confidence: 86%

Influences of Catecholamines on Growth Hormone Release in Female Goldfish, Carassius auratus

Chang¹,

Marchant²,

Cook³

et al. 1985

Neuroendocrinology

View full text Add to dashboard Cite

show abstract

“…4). , 1980;Richardson et al 1983), but a dose-re¬ sponse curve has never previously been established.…”

Section: Resultsmentioning

confidence: 99%

Effects of dopamine and morphine on immunoreactive somatostatin and LH-releasing hormone secretion from hypothalamic fragments in vitro

Lengyel¹,

Grossman²,

Bouloux³

et al. 1985

Journal of Endocrinology

View full text Add to dashboard Cite

Dopamine and morphine modulate GH and LH release, probably at a hypothalamic locus. To investigate this in more detail, we studied the influence of these substances on somatostatin and LH-releasing hormone (LHRH) release from rat hypothalamic fragments in vitro. Hypothalamic fragments were incubated in Earle's medium. After 60 min of preincubation, medium from two 20-min incubations was collected and somatostatin and LHRH levels measured by radioimmunoassay. Dopamine (10 nmol/1-0.1 mmol/l) induced a progressive increase (r = 0.41; P less than 0.01) in basal somatostatin levels. K+ (30 mmol/l)-induced somatostatin release was also increased (r = 0.54; P less than 0.01) by increasing doses of dopamine. Metoclopramide (10 mumol/l) blocked the dopamine (1 mumol/l)-induced increase in somatostatin release. No significant relationship between dopamine and LHRH was found either basally or after K+ (30 mmol/l) stimulation. Basal somatostatin was negatively correlated (r = -0.63; P less than 0.01) with morphine concentrations. No significant correlation was found after K+ (30 mmol/l) depolarization. Basal LHRH release was not influenced by morphine, while K+ (30 mmol/l)-induced release was significantly lower than controls only at a concentration of 10 nmol/l. These results suggest that dopamine and morphine act at a hypothalamic level to modulate GH release through alterations in somatostatin secretion. Dopamine and morphine have no consistent effect on hypothalamic LHRH release.

show abstract

“…This experiment is representative of three others. For details, see Materials and Methods. lates hypothalamic SS release in both in vivo (Junier et al, 1983) and in vitro (Richardson et al, 1983) systems. Robbins (1985) also demonstrated that DA increases SS release from cerebral cortical cells in culture.…”

Section: Discussionmentioning

confidence: 97%

Dopamine enhances somatostatin receptor-mediated inhibition of adenylate cyclase in rat striatum and hippocampus

Puebla

López-Sañudo

et al. 1997

J. Neurosci. Res.

View full text Add to dashboard Cite

Although there is evidence that suggests that dopamine (DA) has stimulatory effects on somatostatinergic transmission, it is unknown to date if DA increases the activity of the somatostatin (SS) receptor-effector system in the rat brain. In this study, we evaluated the effects of the administration of DA and the DA D1-like (D1, D5) receptor antagonist SCH 23390 and the D2-like (D2, D3, D4) receptor antagonist spiperone on the SS receptor-adenylate cyclase (AC) system in the Sprague-Dawley rat striatum and hippocampus. An intracerebroventricular injection of DA (0.5 microgram/rat) increased the number of SS receptors and decreased their apparent affinity in the striatum and hippocampus 15 hr after its administration. The simultaneous administration of the DA receptor antagonists SCH 23390 (0.25 mg/kg, ip) and spiperone (0.1 mg/kg, ip) before DA injection partially prevented the DA-induced increase in SS binding. The administration of SCH 23390 plus spiperone alone produced a significant decrease in the number of SS receptors in both brain areas studied at 15 hr after injection, an effect that disappeared at 24 hr. The increased number of SS receptors in the DA-treated rats was associated with an increased capacity of SS to inhibit basal and forskolin (FK)-stimulated (AC) activity in the striatum and hippocampus at 15 hr after injection. This effect had disappeared at 24 hr. By contrast, basal and FK-stimulated enzyme activities were unaltered after DA injection. No significant changes in the levels of the alpha i (alpha i1 + alpha i2) subunits were found in DA-treated rats as compared with control rats. In addition, the immunodetection of the alpha i1 or alpha i2 subunits showed no significant changes in their levels in DA-treated rats when compared with controls. DA injection also induced an increase in SS-like immunoreactive content in the rat striatum but not hippocampus at 15 hr after administration and returned to control values at 24 hr. These results provide direct evidence of a functional linkage between the dopaminergic and somatostatinergic systems at the molecular level.

show abstract

Dopamine stimulates somatostatin release from perifused hypothalamic cells

Cited by 13 publications

References 19 publications

Influences of Catecholamines on Growth Hormone Release in Female Goldfish, <i>Carassius auratu</i><i>s</i>

Influences of Catecholamines on Growth Hormone Release in Female Goldfish, <i>Carassius auratu</i><i>s</i>

Effects of dopamine and morphine on immunoreactive somatostatin and LH-releasing hormone secretion from hypothalamic fragments in vitro

Dopamine enhances somatostatin receptor-mediated inhibition of adenylate cyclase in rat striatum and hippocampus

Contact Info

Product

Resources

About