Cellular basis of prolactin action: involvement of cyclic nucleotides, polyamines, prostaglandins, steroids, thyroid hormones, Na/K ATPases and calcium: relevance to breast cancer and the menstrual cycle

Prolactin regulates uterine synthesis of prostaglandins in ovariectomized rats. Effect of estradiol 17-beta

We studied the in vitro effect of prolactin on the synthesis of prostaglandins PGE and PGF2 alpha in the rat uterus. Uterine tissue was obtained from ovariectomized adult rats with or without estradiol-17 beta treatment. Prolactin (4 IU/ml) enhanced PGE uterine synthesis. At higher concentrations (10-15 IU/ml) prolactin enhanced PGE levels and diminished PGE2 alpha production by uterine tissue from ovariectomized rats. When ovariectomized rats were injected with estradiol-17 beta, we observed a pattern of PGE and PGF2 beta uterine similar to that of ovariectomized rats. However, the stimulatory action of PRL on PGE synthesis was augmented in the estrogenized animals. These results led us to conclude that: 1)-PRL exerts a luteotrophic action by regulating uterine tissue PGE synthesis, 2-estradiol-17 beta potentiates this action.

The relationship between schizophrenia and essential fatty acid and eicosanoid metabolism

Essential fatty acids (EFAs) and their eicosanoid derivatives are important constituents of the brain and regulators of neuronal function. There is direct and indirect evidence of impaired metabolism of prostaglandin (PG)E1 in schizophrenia. There is also direct evidence of abnormal EFA biochemistry with plasma phospholipids from five populations and brain phospholipids from another all showing reduced levels of linoleic acid and elevated levels of 22-carbon EFAs of both n-6 and n-3 series. Clinical trials of PGE1 and of the PGE1 precursors, gamma-linolenic acid (GLA) and dihomo-gamma-linolenic acid (DGLA) have shown modest therapeutic effects. In view of lack of therapeutic process involving drugs based on the dopamine concept of schizophrenia, it is time for new approaches based on the EFA/PG concept to be evaluated thoroughly.

Effect of increased postmilking prolactin concentrations on lactation, plasma metabolites, and pancreatic hormones in lactating goats

Six lactating dairy goats were utilized in a replicated 3 x 3 Latin square design to examine the effect of increased postmilking prolactin concentrations on lactational performance. Thirty minutes after each milking, either placebo or pituitary-derived ovine prolactin at 2 mg/h or 4 mg/h was infused via jugular cannula for 2 h. Goats were housed in a controlled environment at 19 degrees C and a cycle of 16 h light and 8 h dark. Mean plasma prolactin concentrations after milking were increased 100 and 180% for 2 and 4 mg/h prolactin infusion, respectively. Milk yield was slightly but significantly increased by 2 mg/h prolactin infusion compared with placebo and 4 mg/h prolactin infusion. However, milk composition and yields of milk components were not influenced by treatments. No differences in dry matter intake, digestibility of the diet, or N retention were observed. Circulating concentrations of glucose, nonesterified fatty acids, insulin, and glucagon were not altered.

Effect of prolactin infusion on lactation, glucose kinetics, and pancreatic hormones in lactating goats

To determine lactational and glucogenic responses to increased prolactin concentrations, five lactating dairy goats were used in a crossover design. Prolactin at .85 mg/h or placebo was infused on each of 8 consecutive d via jugular catheter for 14 h initiated 30 min after the a.m. milking. To examine the effect of treatments on glucose metabolism, goats were given a single isotope injection of [6-3H]glucose 2 h after initiation of treatment infusion on the final day of the treatment period. Milk yield and milk protein percentage were not affected by prolactin infusion; however, milk fat and SNF percentage were significantly decreased. No differences in dry matter intake and digestibility of the diet were observed. Prolactin increased plasma prolactin and decreased plasma glucagon concentrations, but did not affect plasma insulin or glucose concentrations. Although glucose pool size per kilogram of BW was significantly lower in the prolactin-treated group than in the control group, no difference in glucose turnover rate was observed.

Evening primrose oil and treatment of premenstrual syndrome

The therapeutic effectiveness of evening primrose oil (Efamol, Vita-Glow) in the relief of 10 symptoms associated with premenstrual syndrome (PMS) as well as menstrual symptoms was studied in 38 women. The prospective trial was randomised, double-blind and placebo-controlled and was crossed-over after three cycles. Although the results showed an improvement in symptoms of PMS during the trial, no significant differences in the scoring between the active and placebo groups were found over six cycles. No "carry-over" effect of active medication was observed; the beneficial effect on all symptoms (psychological, fluid retention, breast) was rapid, the scores decreasing in the first cycle but increasing slightly at the change-over period after the third cycle, irrespective of whether the active or placebo medication was next given. These findings indicate that the improvement experienced by these women with moderate PMS was solely a placebo effect.

A randomized trial of dietary intervention with essential fatty acids in patients with categorized cysts

Two hundred women with breast cysts proven by aspiration were entered into a randomized double-blind trial of Efamol (evening primrose oil) at a dose of 6 capsules daily or equivalent placebo dose for a year. Cysts were categorized by initial electrolyte composition, and follow-up continued for 1 year posttherapy. Recurrent cyst formation in the first year was slightly (but not significantly) lower in the Efamol group compared with the placebo-treated group. The Efamol treatment was well tolerated as the dropout rate was only 7% and equal in both the active and placebo groups. The initial electrolyte composition did not predict for cyst recurrence.

Management of breast pain and nodularity

The management of mastalgia consists of classification into its various patterns: reassurance, drug therapy for severe cases, and, rarely, surgery. Differentiation into cyclical and noncyclical patterns on a simple pain chart is useful for objective assessment of pain severity and for selection of appropriate drug therapy and subsequent monitoring of response. About 85% of new patients will be satisfied with adequate reassurance, but some 15% will have persistent pain and warrant medical treatment. Only a small number of drugs have been adequately tested in controlled trails and have been demonstrated to be more effective than placebo; these are bromocriptine, danazol, evening primrose oil, and tamoxifen. No ideal agent exists and the choice of drug will depend on efficacy, side effects, and cost. Noncyclical pain has a lower response rate compared to cyclical mastalgia, but differentiation of a subgroup with chest wall pain leads to an overall 90% response to treatment by local infiltration with steroid and lignocaine. Newer agents such as LHRH agonists are currently undergoing evaluation in double-blind controlled trials against placebo. The management of nodularity is based on the clinical differentiation of the normal spectrum of physiological change within the breast (ANDI), requiring simple reassurance, from a true dominant breast nodule that will require excision biopsy to exclude malignancy. When pain and lumpiness coexist, some reduction in overall nodularity (with the use of agents given for mastalgia) may occur.

Prostaglandins, brown fat and weight loss

In obesity, a situation is created in which energy intake exceeds energy expenditure. The three components of energy expenditure are resting metabolism, physical activity, and thermogenesis. Increasing attention is being paid to the role of impaired energy expenditure in obesity. Evidence indicates that impairment in activity of the sympathetic nervous system, which stimulates thermogenic processes, contributes to the etiology of obesity. In addition, insulin resistance, a well-recognized metabolic consequence of obesity, appears to interfere with feeding-related, insulin-mediated increases in thermogenesis in brown adipose tissue. This thermogenic defect results in reduced energy buffering by brown adipose tissue leading to deficient energy expenditure and an increased efficiency in weight gain. A unique weight loss program, The Princeton Metabolic Diet Program, is presented. The Program stimulates metabolism by stimulating the sympathetic nervous system and correcting insulin resistance, thereby enhancing thermogenesis in brown adipose tissue. Methods include: 1) alternating diet composition and caloric intake and, 2) the use of nutritional metabolic stimulants. This type of non-toxic therapy, directed at correcting biochemical defects, will enhance metabolic mechanisms and induce weight loss.

Cyclical mastopathy: a critical review of therapy

Because of a recently completed trial which demonstrated that dietary fat reduction improved the symptoms of cyclical mastopathy, we have carried out a critical review of other studies of treatment for this disorder to determine what, if any, mechanisms of action were shared by effective treatments. Therapies were classified as 'definitely effective' if their effectiveness was demonstrated in at least one randomized placebo-controlled study of women with cyclical mastopathy, 'probably effective' if their effectiveness in relieving breast symptoms was demonstrated in at least one study in women with premenstrual syndrome, and 'probably not effective' if they had not been shown to improve breast symptoms in at least two studies in women with premenstrual syndrome. Bromocriptine, danazol, evening primrose oil, tamoxifen and reduction of dietary fat intake were classified as definitely effective and norethisterone and Bellergal as probably effective. Several therapeutic manoeuvres, including reduction of methylxanthine ingestion and the administration of vitamin E or diuretics, have not been adequately evaluated in women with cyclical breast symptoms. A review of the published reports of the physiological effects of therapies that were definitely or probably effective revealed that these agents acted either to alter serum prolactin levels or lipid metabolism, or both. As evidence exists that prolactin influences lipid metabolism it is postulated that cyclical mastopathy may be a disorder of lipid metabolism.

The prolactin response of males to a standard MVO2 treadmill test

The concentration of serum prolactin in response to a standard MVO2 treadmill stress test to self-perceived exhaustion was investigated in 19 normal healthy males. The prolactin concentration remained stable for an interval of approximately 20 minutes from the beginning of exercise. Peak prolactin levels, observed after the subjects had stopped exercising, indicated a mean 2.6-fold increase over pre-exercise levels. The concentration of prolactin did not increase before an exercise intensity reflecting a VO2 of 40 ml/kg/min had been reached. There was no relationship between the MVO2 of the 19 male subjects and their prolactin increment in response to exercise.

Stimulation of in vivo antibody production and concanavalin-A-induced mouse spleen cell mitogenesis by prolactin

Regulation of the immune system by neuroendocrine hormones is receiving increased attention. Prolactin, a hormone normally associated with lactation, has been shown recently to reconstitute immunosuppressed hypophysectomized rats. The present studies demonstrate that prolactin administration to normal mice results in a biphasic stimulation of antibody production to sheep red blood cells. While 100 and 200 micrograms bovine prolactin/animal stimulated antibody production, 400 micrograms had no effect. Potentiation of lectin-induced T-cell mitogenesis by prolactin was also biphasic. As the concentration of prolactin increased the incorporation of [3H]thymidine into the cells first increased and then decreased. Decreasing serum prolactin levels with the dopaminergic agonist bromocriptine resulted in a reduction of antibody titers to sheep erythrocytes and a modulation of thymic weight. These data show that prolactin can stimulate the immune system in a biphasic manner and that a reduction in the basal levels of this hormone results in an attenuated immune response.

A role for glucocorticoids in the polyphosphoinositide second messenger system

Glucocorticoids have been shown to be involved in numerous secretory and activation processes which are known to be mediated by the polyphosphoinositide second messenger system. A connection between glucocorticoids and the polyphosphoinositide system has not been made because of the marked temporal differences in their effects and the fact that most of the known effects of glucocorticoids involve transcription and/or protein synthesis. An attempt is made to to rationalize these apparent incongruities. The recently reported stimulation of glucose transport by kinase C suggests an experimental system to investigate glucocorticoid effects on the polyphosphoinositide system.

Circadian alterations in prolactin, corticosterone, and thyroid hormone levels and down-regulation of prolactin receptor activity by 2,3,7,8-tetrachlorodibenzo-p-dioxin

Studies were initiated to determine whether 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) affects circadian rhythms of serum prolactin (PRL), corticosterone, thyroxine (T4), and triiodothyronine (T3) in male Sprague-Dawley rats. In addition, the effects of TCDD on PRL receptor activity, as assessed by the ability of PRL to induce ornithine decarboxylase (ODC), were determined. The earliest effect detected following TCDD administration was a significant decrease in the serum PRL concentration compared with that of pair-fed controls within 4 hr (p less than 0.05). This was followed by a significant decrease in serum T4 by 6 hr (p less than 0.05). By 8 hr the serum peak of corticosterone was shifted to 2 hr later in the TCDD-treated rats. This temporal sequence of hormonal changes suggests that the earlier alteration in PRL may be involved in the later alterations in the concentrations of serum T4 and corticosterone. The serum PRL concentration 7 days after TCDD administration was significantly higher (p less than 0.05) in TCDD-treated animals compared with that in pair-fed controls (mean of 20.5 +/- 3.7 vs 13.6 +/- 1.8 ng/ml serum, p less than 0.05, respectively). The elevation of ODC activity in response to PRL, 2 days after TCDD, was decreased in the order of thymus greater than adrenal greater than spleen greater than heart greater than kidney greater than liver. By 7 days, liver ODC activity in response to PRL was only 12% that detected in pair-fed controls. Liver ODC activity in response to dexamethasone and aminophylline was decreased to 25 and 22% of pair-fed controls, respectively, by 7 days after TCDD administration. However, in kidney, TCDD-treated rats had an increased ODC response to aminophylline to 191% of pair-fed controls by Day 7. These results suggest that the ability of TCDD to alter receptor coupling or the receptor number for diverse hormones may play a role in TCDD toxicity.

Biological half-life of prostacyclin and 6-oxo-PGF1 alpha levels in plasma of patients with colonic cancer

Prostaglandins have been shown to play a central role in the formation of cancer. The synthesis of prostacyclin and its bioavailability may be an important local determinant for metastasis. As the amount of the biologically active substance is dependent in part on the half-life (T/2) we examined the question as to whether the T/2 of prostaglandin I2 (PGI2) is altered in patients suffering from colonic cancer at various stages of the disease. In addition, the influence of various therapeutic regimens was investigated. In 58 patients with various stages of colonic cancer no significant difference in PGI2-T/2 could be detected. No significant difference could be found before (10, 11 +/- 1, 9 min) and after (10, 03 +/- 1, 8 min) tumor resection, before (9, 89 +/- 1, 5 min) and after 10, 35 +/- 1,8 min) chemotherapy, before (10, 36 +/- 1, 5 min) and after (10, 89 +/- 2, 31 min) irradiation as well as before (8, 86 +/- 1, 9 min) and after (9, 07 +/- 1, 2 min) tumor resection at least 4 to 6 years ago. In 14 healthy people PGI2-T/2 (10, 05 +/- 2, 1 min) did not differ significantly. In all the 58 patients the plasma levels of 6-oxo-PGF1 alpha, the stable derivative of PGI2 were measured. As compared to healthy controls (less than 1 pg/ml) the actual 6-oxo-PGF1 alpha values of patients with colonic cancer were significantly increased. However, no correlation to the T/2 of PGI2 (r between 0, 03 and 0, 21, n.s.) in plasma in vitro could be discovered. After curative tumor resection and after chemotherapy the plasma levels of 6-oxo-PGF1 alpha were significantly lower than before. The data suggest that in patients suffering from colonic cancer the speed of degradation of PGI2 is not a key determinant in local hemostatic dysregulation favouring early metastasis. However, PGI2 or its stable derivatives may be involved in the development of colonic cancer.

Inhibition of human chorionic gonadotropin production by prolactin from term human trophoblast

In vivo suppression of prolactin concentrations by bromocriptine near term, in a pregnant woman with a prolactinoma, was followed by augmentation of human chorionic gonadotropin levels. Suspension of drug therapy at 38 weeks of gestation was followed by a reversal of this sequence of events. In vitro, both ovine prolactin and human prolactin added to explants of term placental trophoblast significantly inhibited human chorionic gonadotropin production from this tissue. Although, with ovine prolactin, this inhibitory effect was demonstrable up to 5 micrograms/ml of ovine prolactin in the culture medium, only doses of 0.1 to 0.2 micrograms/ml of human prolactin significantly suppressed human chorionic gonadotropin production. Overall, 0.1 and 0.2 micrograms/ml of ovine prolactin and human prolactin most consistently suppressed human chorionic gonadotropin production to a statistically significant extent. In general, the concentrations in the culture medium of both ovine prolactin and human prolactin that inhibited human chorionic gonadotropin production in vitro were comparable to the concentrations of prolactin present in the mother and fetus. These in vivo and in vitro observations suggest that prolactin inhibits human chorionic gonadotropin production from term human trophoblast.

Prediction of response to endocrine therapy in pronounced cyclical mastalgia using dynamic tests of prolactin release

Many of the endocrine agents currently used to treat symptomatic benign breast disease modify the action or secretion of prolactin. We have compared the responses to hormonal therapy with dynamic assessment of prolactin control in 29 patients with cyclical mastalgia and in 7 patients with non-cyclical mastalgia. The tests of prolactin release used were direct stimulation by TRH or dopaminergic blockade by domperidone. These were carried out before treatment in the mastalgic patients and also in 22 age-matched asymptomatic controls. The response to treatment was assessed using a special pain chart and visual linear analogue scale. Patients with cyclical mastalgia could be divided into two groups: those in whom the peak prolactin release was exaggerated (greater than 4000 mU/l) and those in whom the prolactin release was less marked and similar to control subjects and patients with non-cyclical mastalgia. Patients in the cyclical mastalgia group with a high peak prolactin release responded to hormonal treatment significantly more frequently (90%) than those with a normal prolactin release (50%). Basal prolactin levels did not correlate with the response to treatment. In the non-cyclical mastalgia group, no patient had peak prolactin release greater than 4000 mU/l and none responded to therapy. This study indicates that dynamic tests of prolactin release in cyclical mastalgia may be useful in predicting the subsequent satisfactory response to endocrine therapy if a high peak prolactin release is induced.

Clinical experience of drug treatments for mastalgia

Results of randomised trials and open studies in 291 patients with severe persistent breast pain in whom breast cancer had been excluded showed that drug therapy produced a good or useful result in 77% of those with cyclical mastalgia and 44% of those with non-cyclical mastalgia. In patients with cyclical mastalgia good or useful responses were obtained with danazol in 70%, with bromocriptine in 47%, and with evening-primrose oil in 45%. The equivalent response rates in patients with non-cyclical mastalgia were 31%, 20%, and 27% respectively. Progestagens were not effective in either group. Failure to respond to one drug did not preclude response to a different drug. Patients with Tietze's syndrome did not respond to drug therapy, but 7 out of 10 responded to injection of lignocaine and hydrocortisone around the affected costochondral junction.

Abnormal essential fatty acid levels in plasma of women with premenstrual syndrome

Premenstrual syndrome is now recognized as a condition that probably has an endocrine or biochemical basis. However, it has proved difficult to demonstrate any consistent significant differences from normal in any parameter measured to date. We have measured essential fatty acid levels in phospholipids in plasma taken from 42 women with well-defined premenstrual syndrome. The women were not on any treatment during the cycles when samples were taken in both follicular and luteal phases. The levels of linoleic acid, the main dietary n-6 essential fatty acid, were significantly above normal, indicating no deficit of intake or absorption. In spite of this, concentrations of all metabolites of linoleic acid were significantly reduced, suggesting a defect in conversion of linoleic acid to gamma-linolenic acid. Possibly in compensation, levels of n-3 essential fatty acids were elevated. The same abnormalities were present in both follicular and luteal phases. This abnormality cannot therefore be the direct cause of the symptoms that appear in the luteal phase, but it may sensitize tissues so that they respond abnormally to normal levels of reproductive hormones.

Prostaglandin stimulation of ornithine decarboxylase activity in mammary gland explants from mid-pregnant mice

The effects of various prostaglandins on ornithine decarboxylase (ODC) activity in mammary gland explants from mid-pregnant mice have been tested. PGE1, E2 and I2 elicit a concentration-dependent stimulation of ODC activity. The minimally effective concentrations are 0.5 ug/ml for PGE1 and E2, and 50 ug/ml for PGF2 alpha and 6-keto-PGF1 alpha. The PGE1 effect had a time course identical to that of prolactin. The prolactin action on ODC activity was attenuated by indomethacin, an inhibitor of prostaglandin biosynthesis. Arachidonic acid stimulated ODC activity and its effect was abolished by indomethacin. The phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine, potentiated the PGE1 effect on ODC activity. The results suggest that the prostaglandins may modulate prolactin's action on ODC activity via a cAMP dependent mechanism.

Some theoretical questions of the peptide and steroid hormone regulation. Part III.: The RLVC hypothesis as a possible mode for the interaction of the peptide and steroid hormone regulation

My previous models for peptide and steroid hormone actions, in accordance with their biological and molecular-informational requirements, suggested possible mechanisms for the subcellular interactions of the two regulatory systems. In my hypothesis the homogeneous or heterogeneous multiligand binding-proteins (receptors, characterized previously) have the ability to bind both steroids and (cyclic) nucleotide phosphates in a unique distribution and sequence. The specificity of such a Receptor-Ligand Variable Complex (RLVC), the pattern of the steroid and/or (cyclic) nucleotide phosphate ligands, is determined by the equilibrium between the actually acting steroids and peptides on the one hand and by the binding possibilities of the receptor on the other.

Effect of perphenazine on growth and zinc-65 uptake of the rat prostatic adenocarcinoma, R 3327

Prolactin affects the growth and function of both normal and carcinatomous prostate tissue. Therefore, the effect of modifying prolactin secretion on the growth of the adenocarcinoma of the rat prostate (R3327) was studied, utilizing chronic administration of the dopamine antagonist perphenazine. At 4 and 8 weeks after tumor inoculation, perphenazine (0.5 and 1.0 mg per dose) was injected for 12-16 weeks. Tumors weighed at autopsy showed that the 0.5 mg dose resulted in significantly smaller and the 1.0 mg dose, in significantly larger tumors than the controls. Perphenazine at both doses increased serum prolactin, but the increase was greater when 0.5 mg was administered. There was a higher uptake of 65Zn when the tumor growth was inhibited as in the animal receiving 0.5 mg of perphenazine. Several possible explanations are offered for the results, including the fact that prolactin might follow a bell-shaped curve in its effect on the tumor and that perphenazine might have other mechanisms of action besides dopamine antagonism.

Prostaglandin E2 and cyclic AMP in tumor and plasma of breast cancer patients

Prostaglandin E2 and cyclic AMP (cAMP) levels were measured in tumors and plasma of 78 patients with benign and malignant breast tumors. Two groups of malignant tissues were found, one with a high level of PGE2 (M = 55.4 pg/mg) and one with a low level (M = 10.7 pg/mg). The low level did not differ significantly from the benign tissue level (M = 8.7 pg/mg). Two malignant groups could not be detected in the plasma levels. Plasma PGE2 concentration (in form of the 13,14-dihydro-15-Keto metabolite) did not reflect the tissue levels, and no difference was found between the benign (M = 59.9 pg/ml) and the malignant (M = 62.3 pg/ml) patients, but both concentrations were higher than those of healthy controls (M = 34.4 pg/ml). The stage of the cancer, the histological classification and, most important, the period of survival, could not be related to the differences in the PGE2 tissue levels. Neither could plasma cAMP be nominated as a breast cancer market because no difference was found between the cAMP levels of benign tumor patients (M = 16.48 pmol/ml), of malignant tumor patients (M = 21.14 pmol/ml) and of healthy controls (M = 19.07 pmol/ml). The conclusion is that although high amounts of PGE2 appear in some malignant breast tumors, they do not affect the clinical situation. These results may explain the failure to treat human breast cancer patients with prostaglandin synthetase inhibitors.

Indomethacin causes a simultaneous decrease of both prolactin binding and fluidity of mouse liver membranes

Indomethacin suppressed the numbers of prolactin receptors detectable in the liver membranes of both male and female C3H mice. This occurred in a dose-dependent fashion with 7.5 mug/gm body weight injected every 4 hours exerting a maximal effect within 20 hours. While injection of 50 mug prolactin every 4 hr increased the number of prolactin receptors in control animals it could not in the indomethacin-treated animals. Membrane fluidity was estimated by fluorescence polarization techniques using the lipid probe 1, 6-diphenylhexatriene. Indomethacin caused a decrease in membrane fluidity, whereas, exogenous prolactin increased the fluidity of the recipients' liver membranes but again could not overcome these suppressive effects of indomethacin. The data suggest that prolactin induces its own membrane-associated receptor by means of the prostaglandin cascade, perhaps by altering the fluidity of the supporting lipid bilayer.

The chronopathology of premenstrual psychopathology

Psychopathology may occur with the following premenstrual chronopathologic characteristic : the symptoms begin about four days before menstruation and end within the first four days of menstrual flow. For the diagnosis of "premenstrual tension syndrome" (PMTS) the complaints must be present for four consecutive menstrual cycles. According to DSM-III criteria PMTS is a mental disorder of shared phenomenology. The major etiologic factor is hyperprolactinaemia alone or in combination with reduced plasma levels of oestrogen or progesteron during the final luteal phase. The premenstrual chronopathology of these three forms of hyperprolactinaemia may explain the pathogenesis of PMTS. Lithium appears to have a favourable effect on the chronopathologic disorder. As to the molecular mechanisms of the pathogenesis, the intracellular affects of prolactin or prostaglandin PGE1 are important. From a pathophysiologic point of view PMTS may be considered a deficiency of PGE1 activity in the hypothalamus and the temporal cortical areas. This is antagonized by lithium. Premenstrual exacerbations of depression or psychosis differ from PMTS as to their clinical symptoms, location, pathogenesis, pathophysiology and treatment. From a pathophysiologic point of view PGE1 may be involved here, too. Implications for further investigation are discussed.

Review: prostaglandins and cancer

This paper reviews work on the role of prostaglandins in cancer. A substantial body of evidence demonstrates elevated amounts of E series of prostaglandins in human and experimental tumors. Blockade of prostaglandin synthesis in vitro or in vivo results in inhibition of tumor growth. Involvement of prostaglandins is implicated in the actions of tumor promoters like phorbol and polycyclic aromatic hydrocarbon carcinogens. Symptoms like hypercalcemia, osteolysis and tumor metastasis are discussed where disordered synthesis and/or action of prostaglandins and related substances might have a role in the altered metabolism associated with neoplasia.

The reversibility of cancer: the relevance of cyclic AMP, calcium, essential fatty acids and prostaglandin E1

Transformed cells in culture can be normalised (made to undergo reverse transformation) by exposure to cyclic AMP, prostaglandin (PG) E1 and certain drugs. One of these drugs, thioproline, has been successfully used in treating human cancer. All cancer cells have a number of common characteristics: they exhibit aerobic glycolysis, they fail to show feedback regulation of cholesterol biosynthesis, they do not regulate cytoplasmic calcium levels normally and they produce excessive amounts of 2 series PGs. It has been known since 1975 that transformed cells cannot make PGE1 because of loss of the delta-6-desaturase enzyme which converts linoleic acid to gamma-linolenic acid. There is evidence that PGE1 acting in concert with thromboxane A2 has effects which make it able to reverse all the metabolic abnormalities common to all cancer cells. It is therefore argued that loss of the ability to make PGE1 and/or thromboxane A2 may be the critical step in malignant change in many forms of cancer. Restoration of normal PGE1 synthesis by providing gamma-linolenic or dihomogammal inolenic acids which will by-pass the blocked desaturase, whould be of value in normalising malignant cells and reversing cancer growth. Since this approach is completely non-toxic it is here seriously suggested that it might be used as a first step in treatment of those cancers where current evidence suggests that delay in the administration of orthodox treatment is unlikely to affect prognosis.

The regulation of prostaglandin E1 formation: a candidate for one of the fundamental mechanisms involved in the actions of vitamin C

Vitamin C stimulates the formation of PGE1 in human platelets. The effect occurs over the physiologically relevant range of concentrations. PGE1 is required for T lymphocyte function and plays a major part in the regulation of immune responses. PGE1 is also important in the regulation of collagen and ground substance metabolism, in cholesterol metabolism and in regulation of responsiveness to insulin. It is proposed that defective formation of PGE1 could account for many of the features of scurvy and for many of the reported therapeutic effects of vitamin C. If correct, vitamin C will be of value only in conjunction with an adequate supply of dihomogammalinolenic acid, the precursor of PGE1. Essential fatty acids, pyridoxine and zinc are all required to achieve this.