A diurnal rhythm was observed in the responsiveness of mice to nociceptive stimuli and in the hyperalgesic activity of endogenous opioid peptides and may partly account for previous controversy over the direct action of naloxone in opiate-naive animals.

https://science.sciencemag.org/content/sci/198/4318/756.full.pdf

Hyperalgesia induced by naloxone follows diurnal rhythm in responsivity to painful stimuli.

Since the isolation of the enkephalins five yr ago, there has been an explosive increase in knowledge concerning the effects of the opiates and opioid peptides. This review deals with the interactions of opiates with the endocrine system in rat and man. The opioid peptides have been demonstrated to exert a variety of effects on pituitary hormone secretion in rat and man. In the rat, opiates stimulate growth hormone, prolactin and ACTH release and inhibit the release of the glycoprotein hormones. In man, the physiologic role of the endogenous opiates appears to be involved predominantly in ACTH and gonadotrophin regulation. Opiate effects are mainly exerted at the level of the hypothalamus but further modulating effects may occur at the pituitary and at end-organs. Opiate-induced hormonal effects appear to be mediated through dopaminergic and/or serotonergic mechanisms. Recent studies have also suggested a possible local neuromodulatory role for the opioid peptides in the control of carbohydrate metabolism and reproductive processes.

The endocrinology of the opiates and opioid peptides

In this review we propose that there are sex differences in how men and women enter onto the path that can lead to addiction. Males are more likely than females to engage in risky behaviors that include experimenting with drugs of abuse, and in susceptible individuals, they are drawn into the spiral that can eventually lead to addiction. Women and girls are more likely to begin taking drugs as self-medication to reduce stress or alleviate depression. For this reason women enter into the downward spiral further along the path to addiction, and so transition to addiction more rapidly. We propose that this sex difference is due, at least in part, to sex differences in the organization of the neural systems responsible for motivation and addiction. Additionally, we suggest that sex differences in these systems and their functioning are accentuated with addiction. In the current review we discuss historical, cultural, social and biological bases for sex differences in addiction with an emphasis on sex differences in the neurotransmitter systems that are implicated.

/pdf/sex-differences-in-the-neural-mechanisms-mediating-addiction-2lhlctn2kv.pdf

Sex differences in the neural mechanisms mediating addiction: a new synthesis and hypothesis.

Current developments in psychopharmacology

The knowledge of the mechanisms regulating electric neuronal activity is fragmented by the wide variety of techniques and experimental models currently used in neurophysiological research. The interest and importance of the results obtained in any research is improved when interpreted in the perspective of the organism functioning as a whole in physiological conditions. Such interpretation, freed of the constraints imposed by the different techniques and experimental conditions used, is especially important when discussing together results obtained at the behavioral, cellular, and molecular level. This article outlines some of the key factors to consider when experiments from different models are interpreted together.

Neuronal activity: from in vitro preparation to behaving animals.

Statistically significant diurnal variations in plasma growth hormone (GH) were found to occur in handled male rats. Peak GH values (at midday) appeared to be inversely correlated with the diurnal pea

Diurnal variations in plasma corticosterone and growth hormone as corrlelated with regional variations in norepinephrine, dopamine and serotonin content of rat brain.

Chronic morphine effects on regional brain amines, growth hormone and corticosterone.

SINCE it was demonstrated that administration of an extract of the anterior hypophysis results in permanent diabetes in several animal species, opinions have differed both as to which hypophyseal hormones affected the Islets of Langerhans and as to the mechanisms involved. With the advent of relatively pure preparations of the pituitary hormones, it has been shown that growth hormone (GH) is diabetogenic (1, 2, 3, 4) and is the only one of the highly purified hormones which will produce permanent diabetes in the intact animal (5). Although it has been pointed out that ACTH in small amounts will potentiate the effect of GH (6), ACTH alone in quite high dosage will not cause permanent diabetes. The permanent diabetes produced by GH is associated with anatomical abnormalities in the Islets of Langerhans and inability on the part of the pancreas to secrete insulin.

Robert A. George

Papers

Diurnal variations in plasma corticosterone and growth hormone as corrlelated with regional variations in norepinephrine, dopamine and serotonin content of rat brain.

Chronic morphine effects on regional brain amines, growth hormone and corticosterone.

Growth hormone-induced reduction of glycosuria and partial repair of the islets of langerhans in partially pancreatectomized diabetic rats1