Observations on the function of the dopaminergic nerves innervating the pituitary gland

Holzbauer, Margarethe; Sharman, D. F.; Godden, Urma

doi:10.1016/0306-4522(78)90145-8

Cited by 92 publications

(31 citation statements)

References 47 publications

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“…This is in agreement with similar findings in the NL of male rats [30]. THDA neurons are osmosensitive [31, 32, 33]. Consequently, the daily rhythm of DA in IL and NL may be a result of THDA neuronal activity being mediated by changes in water intake.…”

Section: Discussionsupporting

confidence: 81%

Characterization of the Dopaminergic Input to the Pituitary Gland throughout the Estrous Cycle of the Rat

DeMaria

Livingstone²,

Freeman³

1998

Neuroendocrinology

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Changes in the concentrations of dopamine (DA) and its major metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), were characterized in the pituitary gland throughout the 4-day estrous cycle of the rat. Female rats were sacrificed at 2- to 3-hour intervals throughout each day of the 4-day estrous cycle. Pituitary glands were removed, and the concentrations of DA and DOPAC were determined by high-performance liquid chromatography coupled to electrochemical detection. The concentration of prolactin (PRL) in serum from these same animals was determined by radioimmunoassay. The concentration of DA in the anterior lobe was constant throughout most of the 4-day estrous cycle. Prior to initiation of the proestrous surge of PRL, there were significant (p <0.05) decreases in the concentrations of both DA and DOPAC in the anterior lobe which returned to elevated baseline levels just prior to the termination of the proestrous surge of PRL. The concentrations of DA and DOPAC in the intermediate lobe exhibited a daily rhythm. However, in the intermediate as well as in the anterior lobe, there were significant (p < 0.001) decreases in the concentrations of both DA and DOPAC, coincident with the initiation of the proestrous surge of PRL. Similarly, coincident with the peak of the proestrous surge of PRL, there were significant (p < 0.001) increases in the concentrations of DA and DOPAC in the intermediate lobe, followed by a return to basal levels and resumption of the daily rhythm. The pattern of the concentrations of DA and DOPAC in the neural lobe was also daily in nature, with peaks occurring between 13.00 and 15.00 h each day of the 4-day estrous cycle. These data, taken together: (1) confirm that a decrease of the concentrations of DA and DOPAC occurs in the anterior lobe prior to the proestrous surge of PRL; (2) reveal that DA is released in a daily pattern at intermediate and neural lobes, and (3) suggest an apparent role for DA released to the intermediate lobe in the regulation of the proestrous surge of PRL.

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Section: Discussionsupporting

confidence: 81%

Characterization of the Dopaminergic Input to the Pituitary Gland throughout the Estrous Cycle of the Rat

DeMaria

Livingstone²,

Freeman³

1998

Neuroendocrinology

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“…Variable effects of exogenously administered dopamine on ADH release have been reported (Forsling et al, 1979;Holzbauer et al, 1980;Racke et al, 1986). Similarly, conflicting results on dopamine content in hypothalamus and hypophysis after water deprivation or salt loading in rats have been reported (Holzbauer et al, 1978). An alternative possibility to explain our results could be that the dopamine antagonists interact with dopamine receptors on collecting duct cells.…”

contrasting

confidence: 46%

Effect of dopamine antagonists on the urine flow of rats infused with hypotonic saline

Angchanpen

Marin-Grez

Schnermann

1988

British J Pharmacology

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1 The probable involvement of dopamine in the regulation of water excretion was investigated by administering dopamine antagonists intravenously to barbiturate -anaesthetized rats undergoing a water diuresis induced by the infusion of 0.83% glucose with 0.3% NaCl at the rate of 9 ml h-'. 2 Administration of 100l ig of the D,-/D2-dopamine antagonist, haloperidol, reduced the enhanced urine flow of rats infused with the hypotonic solution by 69% (from 75.4 ± 13.0 to 23.6 ± 6.0 pI min-', P<0.01). Similarly, the D,-receptor antagonist, SCH23390, reduced urine flow by 58% (from 77.5 ± 9.2 to 32.7 ± 7.2p fmin-', P <0.01) and the D2-receptor antagonist, sulpiride, by 47% (from 66.2 ± 8.6 to 35.1 ± 6.8 pidmin-', P < 0.05).3 The injection of SCH 23390 increased the urine osmolality from 189.6 ± 27.5 to 479.8 ± 45.8 mosm kg-' (P < 0.05). There was no significant change in sodium and potassium excretion in any of the experiments. Blood pressure (BP) decreased after haloperidol and SCH 23390 injection from control values of 121.7 ± 1.7 and 116.5 ± 7.4 to 113.3 ± 3.3 and 106.0 ± 8.8 mmHg respectively (P < 0.05). 4 To study whether the influence of dopamine antagonists on urine flow during water diuresis depends on antidiuretic hormone (ADH), we administered 0.6 Ag d(CH2)5-D-Phe-Ile-AVP (an ADH antagonist) shortly after the injection of l00 g SCH 23390. The preferential V2 ADH-antagonist abolished the antidiuretic effect of SCH 23390 but did not affect its blood pressure reducing effect (from 118.6 ± 5.6 to 103.2 ± 4.6 mmHg, P <0.01). 5 These results suggest that dopamine antagonists blunted the hypotonic saline-induced diuresis by favouring ADH release through an interference with an inhibitory dopaminergic pathway.

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“…33]. Several studies have shown an independent and/or selective activation of the dopaminergic systems at the two sites under various en docrine conditions [7,12,13,21]. Thus, it appears that the suborganization of the tuberoinfundibular dopaminergic system allows for both a coordinated as well as a separate control of dopamine synthesis and secretion at the two sites.…”

Section: Discussionmentioning

confidence: 99%

Chronic Posterior Pituitary Lobectomy: Prolonged Elevation of Plasma Prolactin and Interruption of Cyclicity

Murai¹,

Ben‐Jonathan²

1986

Neuroendocrinology

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We previously reported that the posterior pituitary dopaminergic system participates in the inhibition of prolactin (PRL) secretion in both male and lactating female rats. However, posterior pituitary lobectomy (Lobex) of urethane-anesthetized cycling rats resulted in an elevation in plasma PRL for a short time only. This raises a question regarding the importance of input from the posterior pituitary to the control of PRL secretion during the estrous cycle. The objectives of this study were (1) to examine the chronic effects of Lobex on plasma PRL levels in conscious rats and (2) to determine whether the absence of input from the posterior pituitary interferes with estrous cyclicity. Lobex or sham lobectomy were performed under Brevital anesthesia in estrous rats. Blood was collected from a jugular cannula at hourly intervals on the day of surgery and at 09.00, 13.00, and 17.00 h during the following 4 days. Daily water consumption and vaginal cyclicity were monitored for 14 and 20 days, respectively. Within 2 h after Lobex, the plasma PRL levels rose 3- to 4-fold and remained elevated for 3 days before declining to near control levels on the 4th day. None of the Lobex rats resumed cyclicity within 3–4 days, 50% had an interruption of cyclicity for 4–10 days, and the remainder were noncyclic for more than 11 days. Upon resumption of cyclicity, Lobex rats had 11.3 ± 0.4 oviductal ova which is within the normal range for intact ovulating rats. In contrast, 60% of the sham-operated rats resumed cyclicity within 4 days with an afternoon proestrous surge of PRL, whereas 30% became pseudopregnant, as judged by diurnal peaks of plasma PRL levels and a sustained leukocyte smear for 11–13 days. The daily water consumption of Lobex rats was 3-fold higher than that of sham-lobectomized rats for at least 2 weeks. It is concluded that: (1) Lobex results in a prolonged elevation of plasma PRL levels in conscious rats; (2) the eventual decline in plasma PRL is more likely due to a compensatory activation of the hypothalamic dopaminergic system by the Lobex-induced rise in plasma PRL than to a regeneration of the posterior lobe or restoration of its function; (3) the Lobex-induced PRL rise appears to be the cause of interruption of cyclicity, and (4) the data are consistent with the hypothesis that the dopaminergic inhibition of PRL secretion involves two interdependent systems: one consists of the hypothalamus – long portal vessels – and the second comprises of the posterior pituitary -short portal vessels. Depending upon the endocrine conditions and the nature of hormonal or neuronal stimuli, either one or both systems may be activated.

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Observations on the function of the dopaminergic nerves innervating the pituitary gland

Cited by 92 publications

References 47 publications

Characterization of the Dopaminergic Input to the Pituitary Gland throughout the Estrous Cycle of the Rat

Characterization of the Dopaminergic Input to the Pituitary Gland throughout the Estrous Cycle of the Rat

Effect of dopamine antagonists on the urine flow of rats infused with hypotonic saline

Chronic Posterior Pituitary Lobectomy: Prolonged Elevation of Plasma Prolactin and Interruption of Cyclicity

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