G. Esposti

A clinical study on the relationship between the pineal gland and the opioid system

Recent reports point to a link between the pineal gland and the opioid system. In order to investigate this relationship, two separate studies were performed on humans. Beta-endorphin plasma levels were determined after melatonin administration (0.2 mg/kg b.w. i.m. at 2 p.m.). Melatonin serum values were evaluated after administration of FK 33-824, a met-enkephalin analogue (0.3 mg i.v. infusion at 9 a.m.). A significant decrease of beta-endorphin plasma levels was observed 120 minutes after melatonin injection. Melatonin release was stimulated by FK 33-824, with a peak at 30 minutes. The present results provide evidence of the inhibitory effect of melatonin on beta-endorphin secretion and the stimulatory action of the opioid peptides on the pineal gland. However, further studies will be required to clarify the relationship between the opioid system and the pineal gland.

Action of morphine on melatonin release in the rat

Some data from the literature raised the possibility of an interaction between the opioidergic system and pineal secretion. The present study was undertaken in order to investigate the acute influence exerted by opioids upon plasma melatonin levels in the albino rat. Different doses of morphine hydrocloride were injected (1, 1.5, 2, 3 mg/kg) intraperitoneally into anaesthetized adult male rats bearing a cannula previously inserted into the carotid. Blood samples were collected subsequently at 30‐min intervals, within a period of 90 min following drug administration. Plasma melatonin contents were determined by a radioimmu‐noassay (RIA) method. Acute administration resulted in a dose‐dependent increase in plasma melatonin concentration when compared to the respective controls. This effect is blocked by pretreatment with Naloxone. The present result seem to support the hypothesis that the opioidergic system, in certain circumstances, might contribute to the activation of melatonin secretion.

Clinical Results with the Pineal Hormone Melatonin in Advanced Cancer Resistant to Standard Antitumor Therapies

The pineal hormone melatonin (MLT) is able to exert an oncostatic action. Its possible use in the treatment of human tumors, however, has not yet been investigated. The present study was carried out to evaluate the effects of MLT in patients with metastatic solid tumors resistant to conventional therapies. The study included 54 patients, most of them were affected by lung cancer or colorectal carcinoma. MLT was given intramuscularly at a daily dose of 20 mg at 3.00 p.m. for 2 months; this induction phase was followed by a maintenance period at a dose of 10 mg orally in responder patients or in those with an improvement in performance status (PS). The clinical response was as follows: 1 partial response (cancer of pancreas), 2 minor responses (colon cancer and hepatocarcinoma) and 21 with stable disease. The remaining 30 patients rapidly progressed within the first 2 months of therapy. An evident improvement in PS was achieved in 18 of 54 (33%) cases. These results, by showing an apparent control of the neoplastic growth and an improvement in the quality of life in a reasonable number of cancer patients for whom no other standard therapy is available, would justify further clinical trials to better define the impact of MLT therapy on the survival and quality of life of untreatable advanced cancer patients.

A clinical study of the pineal gland activity in oncologic patients

It has been known for many years that the pineal gland is involved in regulating tumor growth. In order to evaluate the functional activity of the pineal gland in neoplastic diseases, melatonin serum levels and its light/dark rhythm have been determined with the RIA method in patients affected by various forms of tumor. Irrespectively of the type of the tumor and of its localization, existence of two subpopulations has been observed within the oncologic patients, the former with normal levels of melatonin, and the latter with high ones. The light/dark rhythm of melatonin was anomalous in some cases. An evident decrease of serum melatonin values was seen after chemotherapy. It might be interesting to establish whether melatonin levels may conditionate the prognosis of patients with cancer.

Clinical study of melatonin in untreatable advanced cancer patients.

It is known that the pineal gland has some antitumor activity. Melatonin, its most important hormone, has been shown to inhibit tumor growth in vivo and in vitro. Moreover, some investigations have demonstrated an altered melatonin secretion in cancer patients. Despite these interesting data, clinical trials have never been carried out to evaluate the effects of melatonin on human neoplasms. The aim of this study was to draw some preliminary conclusions on melatonin therapy in advanced human neoplasms. Nineteen patients suffering from advanced solid tumors, which did not respond to standard therapies, entered the study. Performance status (PS) was 20 or less in 9 cases, and more than 20 in the other 10. Melatonin was given intramuscularly at a daily dose of 20 mg at 3.00 p.m., followed by a maintenance period with lower doses in patients who had a remission, a stabilization of disease or an improvement in PS. Among patients with a PS higher than 20, a partial response was achieved in one case with cancer of the pancreas; moreover, 5 of 10 had stable disease, but the other 4 cases had a progression; an evident improvement of PS was obtained in 6 of the 10 cases. In contrast, among patients with a very poor PS, 7 of 9 died within the first 2 months of therapy. This preliminary study would suggest that melatonin may be of some value in treating cancer patients in whom standard antitumor therapies have failed, particularly in improving their PS and quality of life.

A study on the relationship between the pineal gland and the opioid system in patients with cancer preliminary considerations

Recent studies showed that both the pineal gland and the endogenous opioid system are involved in the modulation of the immune system and in the regulation of tumor growth. Moreover, a relationship between pineal and opioid system has been demonstrated. In order get an overall view of the psychoneuroendocrine interactions in cancer patients, the levels of melatonin, the most important pineal hormone, and of β‐endorphin have been measured on blood samples collected during the morning. The study was carried out on 54 patients, 42 healthy subjects, and in 34 patients having illnesses other than cancer. Breast cancer, lung carcinoma, and colorectum cancer were the three neoplasms detected in the patients investigated. Growth hormone (GH), somatomedin‐C and prolactin (PRL) levels were also determined. β‐endorphin levels were found to be substantially within the normal range in patients with cancer, whereas those of melatonin were raised in several cases. The β‐endorphin/melatonin ratio was higher than 2 in normal subjects, in non‐neoplastic patients and in most cancer patients without metastases, whereas this ratio was lower than 2 in almost all patients in a metastatic stage of the disease. Neither melatonin levels nor those of β‐endorphin appeared to be significantly correlated with GH, somatomedin‐C, and PRL concentrations. The low β‐endorphin/melatonin ratio observed in metastatic patients suggests the presence of an unbalanced relation between the pineal and the opioid system in those subjects. Therefore, an anomalous relationship between pineal function and opioid activity might play a role in the clinical course of neoplastic disease.

Comparison of the Rat Pinealocyte Ultrastructure With Melatonin Concentrations During Daytime and at Night

The aim of this study was to investigate the ultrastructure of rat pinealocyte during daytime (1600 h) and at night (0100 h) and to compare these observations with serum melatonin levels in the same animals. In addition, pineal melatonin concentrations were determined in other animals. Both serum and pineal melatonin concentrations were significantly higher at night than during daytime (34 and 21 times, respectively). Sizes of pinealocytes, their nuclei, and nucleoli, as well as cross‐sectional areas of mitochondria and granular endoplasmic reticulum were also higher at night than during daytime, whereas areas of lysosomes, Golgi apparatus, and vacuoles containing flocculent material did not differ at the time points studied. In contrast, the number of dense‐core vesicles was higher during daytime. The results of the present study show that morphological patterns of higher metabolic activity of the rat pinealocyte at night when compared to those during daytime correlate with melatonin concentrations.

Alteration of opioid peptide circadian rhythm in cancer patients.

Endogenous opioid peptides have been seen to play a role in regulating immunity and tumor growth. This study was carried out to investigate opioid activity in human cancer. We evaluated by radioimmunoassay β-endorphin plasma levels on blood samples collected at 9.00 a.m. from 121 cancer patients and 42 healthy subjects. In 22 cancer patients and in 12 controls, β-endorphin circadian rhythm was also investigated. Finally, in 14 cancer patients and in 10 controls GH, PRL, FSH, LH and Cortisol serum levels were measured after the administration of a metenkephalin analogue, FK 33–824 (0.3 mg i.v.). No significant differences were seen in β-endorphin mean levels between cancer patients and normal subjects. Moreover, no differences were found between patients with or without metastases, nor between those with or without chronic pain. β-Endorphin circadian rhythm appeared to be altered in 16/22 cancer patients, and anomalous hormonal responses to FK 33–824 were seen in 13/14 patients. This study shows an altered opioid activity in human neoplasms, whose clinical significance remains to be determined.

Acute effects of various chemotherapeutic combinations on hypophyseal and pineal hormone secretions in cancer patients.

It is known that prolonged therapy with cytotoxic drugs may affect the endocrine system. The present study was carried out to establish whether administration of chemotherapeutic drugs acutely influences hypophyseal and pineal activities. Nineteen patients affected by solid tumors were included in the study, 5 of whom were treated with CMF, 4 with FEC, 4 with CEV, and 6 with CDDP. Cytotoxic drugs were intravenously administered. Venous blood samples were collected at zero time and at 30, 60, 120 and 180 min after drug administration. On a separate occasion, venous blood samples were drawn during a saline infusion only. In each sample FSH, LH, GH, PRL, TSH, Cortisol, melatonin and β-endorphin were determined by the RIA method. The only significant changes observed in this study were a rise in PRL and a decrease in β-endorphin after CDDP administration. Melatonin was enhanced after CDDP and CMF, and Cortisol decreased after CMF and FEC, but their variations were not statistically significant with respect to those seen during saline infusion.

Correlation between changes in prolactin and melatonin serum levels after radical mastectomy.

Both prolactin (PRL) and melatonin (MLT) (the most important pineal hormone) have been shown to play a role in regulating breast cancer growth. The present study was carried out to investigate the relationship between PRL and MLT secretions in human breast cancer. Twenty-four women with breast cancer, at clinical stage T1-2 N0-2 M0, were evaluated before and after radical mastectomy. As controls, 14 women who underwent surgery for reasons other than neoplastic disease were included in the study. PRL and MLT serum levels were measured by RIA before and 15 days after surgery. There were no significant differences in mean PRL serum levels between patients and controls; mean MLT serum values were significantly higher in patients than in controls. In no control subject was PRL affected by surgery. In contrast, 13/24 breast cancer women showed high PRL levels after mastectomy; the PRL rise induced by surgery was significantly higher in patients without axillary node involvement. MLT was not affected by mastectomy in 13 patients, whereas it was enhanced in 5 women and decreased in the last 6 cases. No significant correlation was seen between PRL and MLT changes induced by mastectomy. The present study shows that radical mastectomy influences PRL and MLT secretions, however, its clinical significance remains to be established.