EGF binding site number of rat anterior pituitary is increased by chronic administration with dopaminergic agonist, CV 205-502]

In order to assess whether a chronic treatment with a dopamine agonist, CV205-502, could modulate anterior pituitary epidermal growth factor (EGF) binding sites, female Wistar rats were treated or not (controls) with CV205-502 0.25 mg/kg/day sc for 8 days. This treatment significantly reduced rats' pituitary weight and plasma prolactin levels when compared to controls (weight: 10.4 +/- 0.1 vs 11.1 +/- 0.1 mg, p less than 0.01; prolactin: 1.2 +/- 0.2 vs 4.9 +/- 0.5 ng/ml, p less than 0.01). These decreases were associated with a significant stimulation of the number of pituitary EGF binding sites Bmax: 16.7 +/- 2.3 vs 11.3 +/- 1.9 fmoles/mg proteins, p less than 0.01) with no significant effect on their affinity (Kd: 0.94 +/- 0.17 vs 0.95 +/- 0.14 nM). Therefore, the modulation of pituitary EGF binding sites might be one of the mechanisms by which the dopamine agonist, CV205-502, exerts its pharmacological effects on hormonal secretions and/or cell multiplication in the pituitary.     

Hormonal effects of CV 205-502, a novel octahydrobenzo [g] quinoline with potent dopamine agonist properties

Following the success of ergot alkaloids and their synthetic derivatives in treating a variety of pathophysiological disturbances, efforts have been concentrated on the synthesis of new derivatives and partial structures with the aim of dissecting out a specifically dopaminomimetic pharmacophore. Accordingly CV 205-502, a structure which superposes the linear benzo [g] quinoline segment of apomorphine on the substituted pyrrolo [3,4- g] quinoline moiety of the ergolines was designed. This study was performed in normal young volunteers to investigate the effect of single oral doses of CV 205-502 on plasma prolactin levels and on other endocrine parameters (GH, LH, FSH, TSH and cortisol) as well as on tolerability. 10 volunteers participated in a dose-ranging study. They received single oral doses of 0.01 to 0.09 mg CV 205-502, in order to assess the prolactin suppressant action. 6 volunteers were given a dose of 0.06 mg CV 205-502 in order to determine the endocrine profile of the compound. The duration of action of 0.06 mg CV 205-502 was investigated in 6 subjects by measuring plasma PRL and GH levels for 48 h. The results show strong dose-dependent suppression of PRL appearing following doses between 0.04 and 0.09 mg of CV 205-502. PRL was markedly suppressed for more than 24h. and the peaks of the normal sleep profile were abolished. Intermittent transient GH increases occurred during the first 6 hours; sleep profiles were normal. Compared with placebo values, no changes were seen in the levels of any other hormone except TSH, which decreased. Tolerability was good and no drug attributable changes in safety measures occurred. This study demonstrates that CV 205-502 is a potent and long acting PRL suppressant compound and suggest that this novel octahydrobenzo [g] quinoline will prove to be a therapeutically useful dopaminomimetic compound.     

Usefulness of CV 205-502 in a case of allergy to ergot-derived drugs.

This study reports a case of allergy to ergot-derived drugs in a patient with a prolactin (PRL)-secreting microadenoma. The anamnesis revealed allergic reactions to the administration of analgesics and antibiotics. The administration of dopamine agonist drugs, such as bromocriptine (BRC; 2.5 mg) or lisuride (0.2 mg), induced after a few minutes the appearance of nausea, vomiting, postural hypotension, headache, edema of the glottis with dispnea and acroedema. The edemas disappeared a few hours after the administration of antihistaminic drugs while nausea, vomiting, postural hypotension and headache persisted for a few days. Therefore, the patient was tested with another dopamine agonist non-ergot-derived drug, quinagolide (CV 205-502), which did not cause side effects or allergic reactions. Furthermore, not only was the responsiveness to the drug optimal but it also normalized the PRL levels, and menses reappeared after more than a 5-year amenorrhea. This report suggests that ergot-derived drugs, such as lisuride and BRC, seldom induce allergic reactions apart from common side effects. Consequently, the feasibility of using a new drug with a different molecular structure (non-ergot derived) effective in the therapy of hyperprolactinemic syndromes represents a good alternative to conventional therapy.     

Abnormal dopamine sensitivity in some human prolactinomas

In most of human prolactin (PRL)-secreting adenomas, dopamine and dopamine agonists normally suppress the excessive PRL secretion. Nevertheless, a subpopulation of such patients presents a relative insensitivity to the ergot derivative bromocriptine. Six patients with a macroadenoma (n = 5) or microadenoma (n = 1) were considered resistant to bromocriptine which, at a daily dose of 15-60 mg, did not normalize high plasma PRL levels. Culture studies of these adenoma cells showed that: (1) 10(-8) M bromocriptine produced a 32 +/- 16% inhibition of PRL release versus 65 +/- 12% obtained in the same conditions with normal human pituitary cells; (2) sulpiride (10(-6) M) reversed the inhibitory effects of bromocriptine, and (3) the bacterial endotoxins, cholera toxin (10(-11) M) and pertussis toxin (250 ng/ml), respectively, produced a 45-500% increase and a total abolition of bromocriptine-induced PRL inhibition. These observations and recent data of the literature allow to discuss the possibility of receptor or postreceptor defects in such tumors.     

Comparison between a slow-release oral preparation of bromocriptine and regular bromocriptine in patients with hyperprolactinemia: a double blind, double dummy study.

The efficacy and tolerability of a slow-release preparation of bromocriptine (Parlodel SRO) were compared to those of conventional bromocriptine (Parlodel R) in a double blind, double dummy study of 12 hyperprolactinemic women (plasma PRL 81.3 +/- 4.73, ng/ml mean +/- SEM). For 2 weeks, the patients received 2.5 mg b.i.d. Parlodel R or 5 mg once daily Parlodel SRO; for the following 2 weeks, the dose of the drugs was doubled. The patients were then treated, in an open study, with 2.5-10 mg daily Parlodel SRO for 6 months. Both preparations caused a prompt and sharp PRL fall. Hormone levels remained inhibited over the whole month of observation with both preparations. Daily PRL profiles were very close with either drug although morning PRl levels were slightly higher during Parlodel SRO than during Parlodel R administration. Doubling the doses of the two drugs did not result in further significant lowering of PRL values. During the 6-month study with Parlodel SRO, plasma PRL further decreased and normalized in 11 of 12 patients. Clinical improvement occurred in the majority of cases. Tolerability of Parlodel SRO appeared to be better, though without statistically significant differences, than that of Parlodel R. Side effects were less important with the former compound in their number, severity and duration. In conclusion, thanks to its favourable pharmacological profile, Parlodel SRO appears to be a valuable alternative to regular bromocriptine in the management of hyperprolactinemia.     

The Effect of Raloxifene on Serum Prolactin Level in Patients with Prolactinoma

Objective: To evaluate the effect of raloxifene on prolactin (PRL) levels in addition to dopamine agonist (DA) therapy in patients with prolactinoma.Methods: We conducted a retrospective chart review of 14 patients with prolactinoma on stable dose of DA for 6 months who received raloxifene 60 mg daily, as PRL could not be normalized despite being on fairly high doses of DA. Patients were informed that raloxifene is not approved by the Food and Drug Administration for prolactinoma treatment. PRL level was measured at 1 to 6 months after starting raloxifene and at 1 to 3 months following its discontinuation. Raloxifene was stopped in 8 out of 14 patients after 2 (1 to 6) months of treatment as the absolute change in PRL level was felt to be small.Results: The median age and female/male sex ratios were 50 years (range 18 to 63 years), 6/8 respectively. The baseline DA dose was 3 mg/week (0.5 to 7 mg/week) for cabergoline and 15 mg/day for bromocriptine. Ten patients had an absolute and percentage decrease in PRL of 8.3 ng/mL (1.5 to 54.2 ng/mL) and 25.9% (8 to 55%) from baseline, respectively, after 1 to 6 months on raloxifene treatment. Among 10 patients with a decrease in PRL level, 2 (20%) achieved PRL normalization. Two patients had no change in PRL and two patients had an increase in PRL level by 22.8 ng/mL and 8.8 ng/mL (47% and 23.6%), respectively.Conclusion: Raloxifene was associated with a 25.9% (8 to 55%) decrease in PRL level in 10/14 (71%) patients with prolactinoma who were on stable doses of DA including 2 patients (14%) who achieved normoprolactinemia.Abbreviations: CV = coefficient of variation; DA = dopamine agonist; FSH = follicule-stimulating hormone; LH = luteinizing hormone; PRL = prolactin; PTTG = pituitary tumor transforming gene     

Prolactin cycles in sheep under constant photoperiod: evidence that photorefractoriness develops within the pituitary gland independently of the prolactin output signal

The present study investigated photorefractoriness in the prolactin (PRL) axis in hypothalamopituitary-disconnected (HPD) sheep exposed to prolonged long days. In experiment 1, HPD Soay rams transferred from short (8L:16D) to long (16L:8D) days for 48 wk to induce a cycle of activation, decline (photorefractoriness), and reactivation in PRL secretion were treated chronically with bromocriptine (dopamine-receptor agonist) or vehicle from the onset of photorefractoriness. Bromocriptine (0.01-0.04 mg kg-1 day-1; 12-24 wk of long days) blocked PRL release and caused a rebound response after the treatment, but it had no effect on the long-term PRL cycle (posttreatment PRL minimum, mean +/- SEM, 35.3 +/- 0.6 and 37.0 +/- 0.4 wk for bromocriptine and control groups, respectively; not significant). In experiment 2, HPD rams were treated with sulpiride (dopamine-receptor antagonist) during photorefractoriness. Sulpiride (0.6 mg/kg twice daily; 22-30 wk of long days) induced a marginal increase in blood PRL concentrations, but again, it had no effect on the long-term PRL cycle (PRL minimum, 37.9 +/- 0.4 and 37.6 +/- 0.9 wk for sulpiride and control groups, respectively; not significant). The 24-h blood melatonin profile consistently reflected the long-day photoperiod throughout, and blood FSH concentrations were minimal, confirming the effectiveness of the HPD surgery. The results support the conclusion that photorefractoriness is regulated at the level of the pituitary gland independently of the PRL output signal.     

Suppression of luteal function in dogs by luteinizing hormone antiserum and by bromocriptine

Beagle bitches were treated with equine anti-LH serum (ALHS) or the dopamine agonist bromocriptine at selected times during the 2-month luteal phase of the ovarian cycle or pregnancy. After a single injection of ALHS (10 ml, i.m.) at Day 42 of pregnancy (N = 2) or the ovarian cycle (N = 3), progesterone was reduced (P less than 0.05) to 7-24% of preinjection values within 1-2 days, and by 4-8 days returned to levels not different from those in control bitches treated with normal horse serum. Injections of bromocriptine (0.1 mg/kg, i.m.) daily for 6 days caused abrupt declines in progesterone which lasted 6-8 days in bitches treated at Day 8 or 22 of pregnancy (N = 5). In bitches treated at Day 42 of pregnancy (N = 3) or in non-pregnant cycles (N = 4) the bromocriptine treatment caused declines (P less than 0.05) in progesterone which were permanent, extensive (less than 2 ng/ml), and therefore abortive. The declines in progesterone in response to immunoneutralization of LH and to prolactin-lowering doses of a dopamine agonist demonstrate that normal luteal function in dogs requires both LH and prolactin.     

Hormonal regulation of prolactin release by human prolactinoma cells cultured in serum-free conditions

Thyrotropin-releasing hormone (TRH) stimulates the prolactin (PRL) release from normal lactotrophs or tumoral cell line GH3. This effect is not observed in many patients with PRL-secreting tumors. We examined in vitro the PRL response to TRH on cultured human PRL-secreting tumor cells (n = 10) maintained on an extracellular matrix in a minimum medium (DME + insulin, transferrin, selenium). Addition of 10(-8) M TRH to 4 X 10(4) cells produced either no stimulation of PRL release (n = 6) or a mild PRL rise of 32 +/- (SE) 11% (n = 4) when measured 1, 2 and 24 h after TRH addition. When tumor cells were preincubated for 24 h with 5 X 10(-11) M bromocriptine, a 47 +/- 4% inhibition of PRL release was obtained. When TRH (10(-8) M) was added, 24 h after bromocriptine, it produced a 85 +/- 25% increase of PRL release (n = 8). This stimulation of PRL release was evident when measured 1 h after TRH addition and persisted for 48 h. The half maximal stimulatory effect of TRH was 2 X 10(-10) M and the maximal effect was achieved at 10(-9) M TRH. When tumor cells were pretreated with various concentrations of triiodothyronine (T3), the PRL release was inhibited by 50% with 5 X 10(-11) M T3 and by 80% with 10(-9) M T3. Successive addition of TRH (10(-8) M) was unable to stimulate PRL release at any concentration of T3. The addition of 10(-8) M estradiol for up to 16 days either stimulated or had no effect upon the PRL basal release according to the cases. In all cases tested (n = 4), preincubation of the tumor cells with estradiol (10(-8) M) modified the inhibition of PRL release induced by bromocriptine with a half-inhibitory concentration displaced from 3 X 10(-11) M (control) to 3 X 10(-10) M (estradiol). These data demonstrate that the absence of TRH effect observed in some human prolactinomas is not linked to the absence of TRH receptor in such tumor cells. TRH responsiveness is always restored in the presence of dopamine (DA) at appropriate concentration. This TRH/DA interaction seems specific while not observed under T3 inhibition of PRL. Furthermore, estrogens, while presenting a variable stimulatory effect upon basal PRL, antagonize the dopaminergic inhibition of PRL release.     

Role of prolactin and luteinizing hormone in regulating timing of implantation in the spotted skunk

The western spotted skunk exhibits an obligate delay of implantation lasting 200-220 days. The pituitary is essential for luteal activation. The corpora lutea, in turn, secrete the hormones necessary for blastocyst implantation. Two experiments were designed to determine which pituitary hormones are responsible for increasing luteal activity and induction of implantation. Forty-two pregnant skunks with delayed implanting blastocysts were treated as follows: 13 served as untreated controls, 6 received 0.5 mg prolactin (PRL) daily, and 5 received diluent beginning in January. Four received 1.5 mg bromocriptine (CB-154) daily, 3 received both CB-154 and PRL, 3 received diluent, 5 received a gonadotropin-releasing hormone agonist (GnRHa) dispensed from osmotic minipumps, and 3 received diluent dispensed from osmotic minipumps starting in April. The skunks were subjected to a natural photoperiod. Duration of preimplantation and blood levels of progesterone and luteinizing hormone were measured. PRL significantly (p less than 0.05) shortened and CB-154 significantly (p less than 0.05) prolonged the duration of preimplantation when compared to controls (148 +/- 33.6 vs. 251 +/- 3.2 vs. 199 +/- 5.1 days, respectively). PRL was able to reverse the inhibitory effect of CB-154 when both were administered simultaneously (195 +/- 4.0 vs. 251 +/- 3.2 days). GnRHa had no significant (p greater than 0.05) effect on duration of preimplantation (199 +/- 5.1 days) when compared to controls (203 +/- 3.2 days). These results indicate that PRL is the primary pituitary hormone responsible for increased luteal activity and subsequent blastocyst implantation in the spotted skunk.     

Effect of bromocriptine on prostacyclin release and cyclic nucleotides on rat aortic and uterine tissues

The effect of bromocriptine mesylate on cyclic nucleotides and PGI2 release by rat aortic and uterine tissues was investigated. Treatment of rats with bromocriptine (10 mg kg-1 I.P. daily for 14 days) increased PGI2 release by the thoracic aorta from 0.67 +/- 0.02 to 1.4 +/- 0.03 ng/mg wet tissue (P less than 0.001; n = 6). This increase was antagonized by treatment with sulpiride (15 mg kg-l). Incubation of the arterial tissue with bromocriptine (50 micrograms ml-1) in vitro also stimulated PGI2 release. Mepacrine (160 micrograms ml-1) significantly decreased both basal and stimulated PGI2 release. Incubation of myometrial tissue from pregnant rats with bromocriptine (50 micrograms ml-1) in vitro significantly decreased PGI2 release from 1.25 +/- 0.07 to 0.60 +/- 0.08 ng/mg wet tissue (P less than 0.05, n = 6). It also elevated uterine cAMP from 40 +/- 2 to 64 +/- 3 pmoles/100 mg wet tissue. Both effects were antagonized by sulpiride. Bromocriptine did not affect uterine cGMP or the cyclic nucleotides in the aorta. It is concluded that the increase in aortic PGI2 was mediated via activation of dopamine D-2 receptors that stimulate phospholipase A2 enzyme. The decrease in myometrial PGI2 release may be related to the increase in uterine cAMP resulting from activation of dopamine D-1 receptors. Previous studies suggested a role for PGI2 in implantation in the rat. The results suggest that the inhibitory effect on uterine PGI2 may underlie the reported inhibition of bromocriptine on implantation. On broad basis, the decrease in uterine PGI2 together with the reported luteolytic effect of bromocriptine point to a potential role for the compound in postcoital contraception.     

Effect of bromocriptine on serum TSH in euthyroid patients with endocrine disorders

In 10 euthyroid subjects a single 2.5 mg per os dose of bromocriptine caused rapid and remarkable decreases in serum TSH. As much as a 0.85 +/- 0.18 (s.d.) microU/ml decrease from the basal level (56 +/- 9%) was observed at 5 hours. A good correlation was observed between the basal TSH level and the TSH decrease after bromocriptine (r = 0.786). In 4 patients taking 5 to 15 mg bromocriptine daily (chronic administration group), another 2.5 mg bromocriptine also caused significant decreases in serum TSH, but the degree (0.42 +/- 0.03 microU/ml, 43 +/- 26% of basal) and duration (maximal at 4 hours) were less than those observed in the untreated group. The lowest TSH levels in these two groups did not differ significantly (0.80 +/- 0.45 and 0.78 +/- 0.53 microU/ml, respectively). The TSH decrease after bromocriptine in the untreated group was found not to correlate significantly with TRH induced TSH increase (r = 0.300). TRH induced TSH increase in the chronic administration group was similar to or greater than that of control subjects with matched basal TSH. The TSH lowering effects of per os prednisolone and triiodothyronine were also studied. Prednisolone exerted a quite similar effect to bromocriptine, but a certain time lag was observed in the case of triiodothyronine. A single dose of bromocriptine was found to lower serum TSH levels even in euthyroid subjects. The effect was considered to be independent of TRH-TSH regulation and to act directly on the TSH release.     

Increased circadian prolactin release is blunted after body weight loss in obese premenopausal women

We recently showed that prolactin (PRL) release is considerably enhanced in obese women in proportion to the size of their visceral fat mass. PRL release is inhibited by dopamine 2 receptor (D2R) activation, and dietary restriction/weight loss are associated with increased dopaminergic signaling in animals. Therefore, we hypothesized that enhanced PRL release in obese humans would be reversed by weight loss. To evaluate this postulate, we measured 24-h plasma PRL concentrations at 10-min intervals in 11 obese premenopausal women (BMI 33.3 +/- 0.7 kg/m2) before and after weight loss (50% reduction of overweight/15% absolute weight loss, using a very low-calorie diet) in the follicular phase of their menstrual cycle. The 24-h PRL concentration profiles were analyzed by a peak detection program (Cluster) and a wave form-independent deconvolution technique (Pulse). Spontaneous 24-h PRL secretion was significantly reduced in obese women [mean daily release, before 128 +/- 24 vs. after weight loss 110 +/- 17 microg/liter distribution volume (Vdl)(-1) x 24 h, P = 0.05]. Body weight loss particularly blunted PRL secretory burst mass (Pulse area, before 230 +/- 28 vs. after weight loss 221 +/- 31 microg/Vdl(-1) x 24 h, P = 0.03), whereas burst frequency was unaffected (no. of pulses, before 11 +/- 1 vs. after weight loss 12 +/- 1 n/24 h, P = 0.69). Thus elevated PRL secretion rate in obese women is significantly reduced after loss of 50% of overweight. We speculate that amelioration of deficit D2R-mediated neurotransmission and/or diminutions of circulating leptin/estrogen levels might be involved in the physiology of this phenomenon.     

Role of the prostaglandin system in the monoaminergic control of prolactin release in the rat]

In ovariectomized rats treated with estradiol benzoate, the pre-treatment with bromocriptine or metergoline on increase of PRL secretion induced by some prostaglandins has been investigated. The PGs used were able to hinder the drop in PRL levels induced by metergoline, a blocker of 5-HT receptors, but not that produced by bromocriptine, a dopamine receptor agonist. Therefore it is possible to suppose that the PGs are involved in the monoaminergic hypothalamic regulation of the PRL secretion.     

Postoperative hypoparathyroidism: long term observation and therapy]

Hundred thirty patients with surgical hypoparathyroidism were followed up. Group I involved 45 patients with mild and group II--85 patients with severe surgical hypoparathyroidism. A delay in vitamin D3 therapy was X +/- SD = 4.2 +/- 8.1 years. A delay in introducing vitamin D3 therapy correlated with the duration of hypoparathyroidism (r = 0.93; 8.9 +/- 9.6 years). Follow up period lasted for 15 years and was 4.3 +/- 3.8 years out of which the attempts to establish ultimate and effective dose of vitamin D3 lasted 1.8 +/- 2.4 years. Dose of vitamin D3 was adjusted 5 times, on the average. Effective daily dose was 4,200-22,500 IU (9,311 +/- 7,252) in group I, and 30,000-195,000 IU (51,385 +/- 32,978) in group II whereas maximum daily dose was 75,000 and 250,000 IU respectively (p < 0.001). Some patients were given 25-OH-D3 in daily doses of 50-225 micrograms or 25(OH)2-D3 in daily dose of 0.10-0.75 micrograms. Calcium oral doses of 400-1600 mg daily were administered to 115 patients. In case of high hypercalciuria (over 350 mg/24 h) hydrochlorothiazide (43 +/- 17 mg a day) or chlorthalidone (60 +/- 22 mg a day) normalized calciuria. Low phosphate diet and aluminium oxide (4.4 +/- 1.7 g a day) were more frequently used in group II. Period of time necessary to establish an effective dose of vitamin D3 is long in patients with surgical hypoparathyroidism. Several dose adjustments are required. Maximum daily vitamin D3 dose required for normocalcemia is approximately higher by 1/3 in the early period of the treatment than the effective maintenance dose. A decrease in diet phosphate content, inhibition of phosphates absorption in the gut or blocking increased calcium loss with the urine are necessary in some patients, only.     

Prolactin lowering effect of amphetamine in normoprolactinemic subjects and in physiological and pathological hyperprolactinemia

The effect on plasma prolactin (PRL) of d-amphetamine (Amph) was studied in normo- and hyperprolactinemic subjects. In normoprolactinemic women Amph failed to lower plasma PRL levels when infused intravenously over 1 h at the dose of 7.5 mg, but induced at the dose of 15.0 mg a modest inhibition of plasma PRL (maximum PRL inhibition 20 +/- 4.5% at 45 min). Likewise, in puerperal women Amph at the dose of 7.5 mg did not decrease significantly plasma PRL levels but it was active in this respect (maximum inhibition 37 +/- 10% at 120 min) at the dose of 15.0 mg. In subjects with presumptive evidence of a PRL-secreting adenoma, Amph at either the 7.5 mg or the 15.0 mg dose failed to alter baseline PRL levels. These results indicate that Amph is a poor PRL suppressor in either normo- or hyperprolactinemic subjects. It is proposed that this may be due to the drug's ability to effect release of dopamine mainly from a non-granular pool of the amine.     

Influence of bupropion HCl (Wellbatrin), a novel antidepressant, on plasma levels of prolactin and growth hormone in man and rat.

Bupropion HCl (Wellbatrin®), a non-tricyclic compound with antidepressant effects in man, was evaluated for effects on plasma prolactin (PRL) and growth hormone (GH) levels in normal human subjects, and for effects on plasma PRL levels in a series of pharmacological studies in normal rats. Single oral doses of 50, 100 or 200 mg of bupropion given to male (n=6) and female (n=12) subjects produced a marked suppression (80% decrease) of PRL. Incomplete PRL recovery was observed at the end of 24 hours. One hour after drug administration there was a +0.56 correlation of percent decrease in PRL levels with bupropion plasma levels. GH showed only small and erratic changes in plasma levels at 1–4 hours post-dose. In the rat, single bupropion doses of 25 mg/kg, i.p., failed to lower basal PRL levels. Bupropion, however, significantly decreased PRL in rats in which plasma PRL was elevated by pretreatment with alphamethyltyrosine, 5-hydroxytryptophan or quipazine. Bupropion, on the other hand, did not counteract the PRL-elevating effect of haloperidol. Results in man and rat are consistent with the view that bupropion has significant dopamine mimetic properties. Whether bupropion is a direct dopamine receptor-stimulator or an indirectly acting agonist cannot be determined from the present results.     

Increased plasma VIP concentration in patients with prolactinoma.

Vasoactive intestinal polypeptide (VIP) is now considered to be a prolactin-releasing factor (PRF). The aim of this study was to determine the VIP concentration in peripheral blood in patients with prolactin-secreting adenoma compared to healthy subjects. We also examined the effect of bromocriptine administration on the plasma VIP concentration in patients with prolactinoma. Nine patients with prolactinoma (6 women and 3 men, aged 27-50) and 7 healthy control subjects (4 women and 3 men, aged 26-40) were examined. Blood samples for prolactin and VIP were collected at 06:00, 12:00, 18:00, 24:00. In prolactinoma blood was taken before and after bromocriptine administration. Serum prolactin concentration was determined by the radioimmunoassay. VIP concentration was measured by a specific radioimmunoassay Kit-INCSTAR Corp. (Minnesota, USA). Statistical significance was calculated using the analysis of variance. A single 5 mg oral dose of bromocriptine decreased the mean prolactin concentration during the first 24 hours of treatment. Plasma VIP concentration was higher in prolactinoma patients compared to healthy subjects. There was no change in plasma VIP level after bromocriptine administration. In conclusion: in patients with prolactin secreting adenoma the plasma VIP concentration is increased.     

Activation of dopamine D2 receptors simultaneously ameliorates various metabolic features of obese women

The metabolic syndrome comprises a cluster of metabolic anomalies including insulin resistance, abdominal obesity, dyslipidemia, and hypertension. Previous studies suggest that impaired dopamine D2 receptor (D2R) signaling is involved in its pathogenesis. We studied the acute effects of bromocriptine (a D2R agonist) on energy metabolism in obese women; body weight and caloric intake remained constant. Eighteen healthy, obese women (BMI 33.2 +/- 0.6 kg/m(2), mean age 37.5 +/- 1.7, range 22-51 yr) were studied twice in the follicular phase of their menstrual cycle in a prospective, single-blind, crossover design. Subjects received both placebo (P; always first occasion) and bromocriptine (B; always second occasion) on separate occasions for 8 days. At each occasion blood glucose and insulin were assessed every 10 min for 24 h, and circadian plasma free fatty acid (FFA) and triglyceride (TG) levels were measured hourly. Fuel oxidation was determined by indirect calorimetry. Body weight and composition were not affected by the drug. Mean 24-h blood glucose (P < 0.01) and insulin (P < 0.01) were significantly reduced by bromocriptine, whereas mean 24 h FFA levels were increased (P < 0.01), suggesting that lipolysis was stimulated. Bromocriptine increased oxygen consumption (P = 0.03) and resting energy expenditure (by 50 kcal/day, P = 0.03). Systolic blood pressure was significantly reduced by bromocriptine. Thus these results imply that short-term bromocriptine treatment ameliorates various components of the metabolic syndrome while it shifts energy balance away from lipogenesis in obese humans.     

Diazepam tolerance: effect of age,regular sedation,and alcohol.

The dose of intravenous diazepam required for sedation was estimated in a series of 78 patients aged 17-85 years given the drug for dental and endoscopic procedures. Multiple regression analysis showed a significant correlation (r = 0.71; p less than 0.001) between dose and age, body weight, the taking of regular sedation, and the taking of more than 40 g alcohol daily, but there were no differences in the doses required between men and women, smokers and non-smokers, inpatients and outpatients, or dental and endoscopy patients. Patients aged 80 required an average dose of 10 mg and patients aged 20 an average dose of 30 mg, and the dose required was much higher in those receiving regular sedation or having a high alcohol intake. Plasma total and free diazepam concentrations were measured in the second half of the series of patients (n = 37). Plasma concentrations required for sedation fell twofold to threefold between the ages of 20 and 80 and were significantly higher in those taking regular sedation or alcohol. Differences in the acute response to diazepam appeared to be due to differences in the sensitivity of the central nervous system (pharmacodynamic tolerance) rather than to differences in pharmacokinetic factors.