Are all males equal? Anatomic and functional basis for sexual orientation in males

In non-human primates anterior hypothalamic nuclei are closely involved in heterosexual activity in males. In humans, hypothalamic nuclei which correspond to these nuclei in non-human primates have been shown to have a neuronal density in homosexual men that is approximately half of that seen in heterosexual men. In addition, homosexual men exhibit a positive luteinizing hormone response to acutely administered estrogen that is intermediate between women (flat response) and heterosexual men (exaggerated response). Furthermore, on the basis of serum testosterone concentrations in similarly feminized transsexual males on estrogen/progestogen treatment 3 distinct groups can be identified. It is postulated that anatomic differences in the anterior hypothalamic nuclei that regulate sexual orientation in males may lead to alteration in the gonadotropin releasing hormone (GnRH) pulse/frequency leading to a more female-type pattern of gonadotropin secretion in homosexual males. Based on data in transsexual males this pattern may be more or less of the female-type in subsets of male homosexuals.

Immobilization osteoporosis in paraplegia

The pathophysiology of osteoporosis as it relates to immobilization or disuse osteoporosis in paraplegics is briefly reviewed. The physiology of bone formation and resorption is discussed, and the influence of piezoelectric forces on bone integrity and the consequences of the loss of this effect in paraplegics is addressed. When bone is stressed, negative charges accumulate on the side from which the stress is applied and positive charges accumulate on the opposite side. Presumably the collagenous component of bone plays the major role in the generation of electrical potentials. Another mechanism important in the generation of electrical potentials is created by liquid planes streaming past solid planes. Diminished forces acting on bone, as in paraplegia, are translated into changes in the activity of bone remodeling units which can be assessed by histomorphic and histoenzymatic techniques. Other biochemical and endocrine consequences of immobilization involve increased serum calcium, decreased serum parathyroid hormone (PTH), and decreased dihydroxy-vitamin D synthesis. Urinary hydroxyproline and calcium excretion are increased, as is stool calcium. The bone loss that follows immobilization may produce an increased susceptibility to fractures involving long bones more than the spinal column, and is due more to decreased bone formation than to accelerated bone resorption. The treatment of immobilization osteoporosis primarily involves early remobilization, but other treatments, including the use of electrical fields and the administration of bisphosphonates, calcitonin, and a growth hormone are being actively investigated.

Hormone pattern in pharmacologically feminized male transsexuals in the California State prison system

The hormonal profile of 40 transsexual inmates from a pool of 86 inmates in the California State prison system was studied before and after therapy with feminizing hormones. Clinical and social data were obtained on all 86 inmates; the incidence of human immunodeficiency virus (HIV) seropositivity was examined in 76 of the 86 individuals. Despite similar degrees of feminization in all 40 individuals in whom hormonal studies were performed, variable suppression of serum testosterone concentrations was present. Based on their testosterone concentrations while on feminizing hormone therapy, the transsexual inmates could be divided into three groups. In Group I (the "suppressed" group), the serum testosterone concentrations were markedly depressed (less than 10 ng/dL); in Group II (the "non-suppressed" group), the values of testosterone were normal (446 to 1072 ng/dL); and in Group III (the "intermediate" group), the testosterone values were between those of the suppressed group and the nonsuppressed group. We speculate that feminizing hormone therapy may induce the development of a state of target hormone resistance to testosterone that results in similar degrees of feminization independent of the circulating concentrations of testosterone. The incidence of HIV seropositivity (3/76) was considerably less than anticipated based on previous studies in populations at high risk for developing the acquired immunodeficiency syndrome.

The endocrinology and pathophysiology of alcoholic cirrhosis and functional renal failure--a review

The pathophysiology and characteristics of decompensated alcoholic cirrhosis and functional renal failure are reviewed. The review will be restricted to alcoholic cirrhosis, because most cases of functional renal failure in the United States occur in the setting of alcoholic cirrhosis, which is also the most common cause of ascites in North America and Europe. Moreover, hepatorenal syndrome may complicate other forms of liver disease besides alcoholic cirrhosis, but the pathogenesis in such circumstances may not be the same as in the cirrhotic state.

Effective portal insulin delivery with enzyme-protected capsules in pancreatectomized pigs

1. Plasma concentrations of insulin, C-peptide, glucagon and glucose were measured in surgically pancreatectomized pigs given insulin into the colon directly and in enteric peptidase-resistant (methacrylic acid copolymer-encapsulated) form. 2. Following introduction of insulin-containing capsules, plasma insulin concentration rose from 2.7 +/- 0.1 microU/ml to 110.9 +/- 51.9 microU/ml in the portal vein, and from 2.6 +/- 0.1 microU/ml to 26.9 +/- 7.3 microU/ml in the systemic circulation. Corresponding portal and systemic values after direct (non-encapsulated) insulin instillation were 28.2 +/- 15.9 microU/ml to 44.8 +/- 13.0 microU/ml and 7.5 +/- 2.6 microU/ml to 15.2 +/- 2.5 microU/ml respectively. Insulin concentrations peaked at 75 min in the group as a whole and between 60-90 min in individual animals. Absorption was most pronounced in pigs given aprotinin (a trypsin inhibitor) with insulin. 3. Plasma portal vein glucose concentrations fell from 76.2 +/- 8.9 mg/dl to 31.1 +/- 3.2 mg/dl 150 min after encapsulated insulin administration. Corresponding systemic glucose levels were 84.5 +/- 11.0 mg/dl and 37.0 +/- 1.4 mg/dl. 4. Colonic administration of insulin in methacrylic acid coated capsules results in peak portal and systemic insulin levels 60-90 min after administration. Co-administration of aprotinin enhances the fraction of insulin absorbed.

Inhibin and gonadotrophin secretion in physically active males after acute exercise

Serum concentrations of luteinizing hormone (LH) follicle stimulating hormone (FSH), testosterone and inhibin were measured in six physically active male volunteers after heavy exercise on a treadmill. Hormone measurements were made before exercise, immediately after exercise and at 30-min intervals for 3 h after exercise. Serum concentrations of LH fell after exercise reaching nadir values between 60 and 180 min post-exercise. The nadir value of LH for the group as a whole occurred 90 min after exercise. Serum testosterone concentrations paralleled the changes in LH concentrations. Serum FSH and inhibin concentrations did not show any appreciable change from baseline values. The data suggest that acute exercise does not significantly lower serum concentrations of FSH or inhibin. Whether repetitive and prolonged heavy exercise, as in competitive runners, produces alterations in serum inhibin concentrations remains to be determined.

Corticotropin releasing hormone and gonadotropin secretion in physically active males after acute exercise

Plasma concentrations of corticotropin releasing hormone (CRH) and the serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, adrenocorticotropic hormone (ACTH) and cortisol were measured in seven physically active males after acute exercise on a treadmill using the Bruce protocol. Measurements were made in the basal pre-exercise state, immediately after exercise, and at 30-min intervals for 3 h after exercise. Serum LH concentrations declined following exercise reaching nadir values between 60 and 180 min after exercise (90 min post exercise in the group). The nadir values in individual volunteers were significantly lower than both the baseline and post-exercise levels. This fall in serum LH concentration appeared to follow a slight but significant elevation of the plasma concentration of CRH which reached peak levels when measured immediately post exercise. Plasma ACTH concentrations paralleled the rise in CRH, but fell to undetectable levels of below 13.8 nmol.l-1 (less than 5 ng.l-1) 60 min after exercise. Plasma cortisol concentrations peaked approximately 30 min after the rise in ACTH, after which they gradually declined to baseline levels. Plasma testosterone concentrations paralleled the concentrations of LH. The data suggest that CRH, on the basis of its previously described gonadotropin-depressant property, may be the hormone involved in the exercise-mediated decline in serum LH. Alternatively, some as yet unidentified factor(s), may be involved in producing the altered concentrations of both LH and CRH.

Hypothesis: insulin is responsible for the vascular complications of diabetes

It is proposed that the systemic hyperinsulinemia and hepatic portal hypoinsulinemia that occurs with conventional injectable preparations of insulin currently used in the treatment of patients with diabetes mellitus is largely responsible for the morbidity associated with this disease. Epidemiological evidence and animal experimentation strongly support systemic hyperinsulinemia as a major factor in genesis of atherosclerosis in diabetic patients. In addition, in vitro studies demonstrate a direct effect of insulin on endothelial cell and arterial smooth muscle proliferation. On the other hand, inadequate hepatic delivery of insulin is associated with overproduction of renal vasoregulatory factors leading to glomerular hyperfiltration and ultimately to glomerulosclerosis and its clinical endpoint--end-stage renal disease. In the absence of widespread success of pancreatic and islet-cell transplantation as a means to deliver insulin physiologically into the hepatic portal circulation, methods must be devised and perfected to accomplish such delivery using approaches such as orally administering insulin in intestinal-enzyme protected capsules. Until such methods of delivery are available for safe and widespread use, one should abandon the illusory goal of rigid glucose control in favor of methods that reduce insulin requirement. Along these lines, dietary restriction and aerobic exercise should be the major life style changes advised for diabetic patients. Reduction of glomerular hyperfiltration in diabetic patients can be promoted with the use of low protein diets and/or angiotensin converting enzyme inhibitors.

Glomerulopressin activity in carbon tetrachloride-induced cirrhosis in male rats

The activity of glomerulopressin, a putative renal vasoregulatory hormone that is synthesized in the liver, was assayed in male rats with carbon tetrachloride-induced cirrhosis and the results were compared to glomerulopressin activity in normal-control and pair-fed animals. Glomerulopressin activity in blood samples collected from the hepatic vein of the cirrhotic group was significantly lower than the activity in the normal-control and pair-fed groups. Glomerulopressin activity in the normal-control and the pair-fed groups were not significantly different. The data support the concept that glomerulopressin deficiency in liver disease, such as cirrhosis, may play a role in the genesis of the functional renal failure associated with liver disease.

Insulin and C-peptide levels following oral administration of insulin in intestinal-enzyme protected capsules

1. Crystalline beef insulin was administered orally in capsules composed of a methacrylic acid copolymer which prevented breakdown of the insulin by enteric and pancreatic peptidases. 2. In studies performed in 3 individuals blood was sampled before oral ingestion of the insulin (40 144 units), and at 15 or 30 min intervals thereafter for 5.5 hr for measurement of immunoreactive insulin and C-peptide concentrations. 3. Following the administration of oral insulin, plasma immunoreactive insulin concentrations became elevated 4-5 hr after ingestion. 4. The rise in plasma insulin concentrations was associated with a corresponding fall in the concentration of C-peptide. 5. The data suggest that this preparation of oral insulin can produce significant enteric absorption of the peptide, and that further investigation of agents that facilitate insulin absorption from the gut might render the use of methacrylic acid copolymer coated capsules a physiologically sound and a commercially feasible method of oral insulin administration.

Male hypogonadism due to nontumorous hyperestrogenism

Male hypogonadism due to the nontumorous production of estrogen was studied in a patient with gynecomastia and bilateral small testicles. Both the gynecomastia and the decrease in testicular size developed in the 5-year period before presentation. Peripheral serum concentrations of testosterone were in the low to low-normal range, while those of 17 beta-estradiol (E2) were significantly elevated, as were the urinary concentrations of total estrogen. Steroid hormone concentrations were measured in the left and right spermatic veins and the left and right adrenal veins in the basal state, and after stimulation with GnRH and ACTH. Spermatic vein concentrations of E2 were 3 to 20 times higher than concentrations previously reported in normal males. Spermatic vein concentrations of testosterone were normal. The spermatic vein concentrations of androstenedione were approximately three times higher than the mean concentration of androstenedione previously reported in the spermatic vein of normal males. The concentrations of E2 and androstenedione in the adrenal veins were also significantly elevated when compared to the concentrations previously reported in normal subjects. The authors postulate that the hyperestrogenism in this patient was due to increased aromatization of the precursor substrates, testosterone in the testes, and androstenedione in the adrenals to E2 and E1 in the testes and adrenals, respectively. Alternatively, an increased abundance or activity of the 17 beta-hydroxysteroid dehydrogenase isoenzyme which converts estrone (E1) to E2 or a relative deficiency of the 17 beta-hydroxysteroid dehydrogenase isoenzyme, which converts androstenedione to testosterone, could theoretically account for the reported abnormalities.

Glucose intolerance in renal failure: role of endogenous opioids

Plasma concentrations of glucose, insulin, and beta-endorphin/beta-lipotropin were measured in male Sprague-Dawley rats with experimental renal failure after intravenous glucose challenge in the presence and absence of opioid blockade with intravenously administered naloxone. The results were compared with those obtained in sham-operated normal control and pair-fed groups of animals. Baseline glucose concentrations were similar in the three groups of animals. Plasma baseline insulin concentrations were significantly lower in the rats with renal failure and the pair-fed animals compared with the normal controls. After glucose challenge the renal failure group demonstrated glucose intolerance, which was not improved after naloxone treatment given 15 minutes before glucose challenge. Peak insulin levels after glucose challenge in the renal failure and pair-fed groups increased significantly after naloxone administration. Interestingly, circulating concentrations of plasma beta-endorphin/beta-lipotropin were not significantly different in the three groups of animals when measured either in the baseline state or after glucose challenge. The data indicate that the carbohydrate intolerance in experimental renal failure may be partly due to an increase in pancreatic islet opioidergic tone, because an improvement in insulin secretion was demonstrated in the absence of any change in circulating beta-endorphin/beta-lipotropin concentrations after naloxone. The failure to demonstrate any improvement in glucose disposal after naloxone, despite the augmented secretion of insulin after naloxone in the animals with renal failure, points to peripheral resistance to the effects of insulin that is not influenced by opioid blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic peptide, arginine vasopressin, aldosterone and plasma renin activity in carbon tetrachloride-induced cirrhosis in rats

The concentrations of atrial natriuretic peptide, arginine vasopressin, aldosterone and the plasma renin activity were studied in male rats with carbon tetrachloride-induced compensated cirrhosis, and the results were compared to those of normal control animals. The rats with cirrhosis exhibited significantly higher plasma renin activity values when compared with the control group. However, plasma concentrations of atrial natriuretic peptide and arginine vasopressin were not significantly different in the two groups. Plasma aldosterone concentrations were significantly higher than those found in the normal control group in approximately 50% of the cirrhotic animals, and were equal to or less than the control values in the rest. This dissociation between plasma renin activity and aldosterone values in some of the cirrhotic animals is interesting and parallels observations made in humans with alcoholic cirrhosis. The results suggest that experimentally induced, apparently compensated cirrhosis may be associated with a perceived decrease in effective circulating volume, and that there is no absolute deficiency of atrial natriuretic peptide in this model of cirrhosis.

Relationship between beta-endorphin/beta-lipotropin, hyperglycemia, and hyperinsulinemia in obese male Zucker rats

The relationship between beta-endorphin(beta-EP)/beta-lipotropin(beta-LP) and insulin secretion in the basal state and after glucose challenge was studied in obese male Zucker rats and their lean littermates. Baseline plasma beta-EP/beta-LP concentrations were similar in the two groups of animals. Baseline plasma insulin and serum glucose concentrations were significantly higher in the obese animals. Following glucose challenge, the increase in plasma beta-EP/beta-LP concentrations was significantly lower in the obese animals than in their lean littermates. Opioid blockade with naloxone failed to alter the baseline hyperinsulinemia and hyperglycemia seen in the obese animals. The data suggest that the hyperinsulinemia in the obese Zucker rat is not due to endogenous hyperendorphinemia as shown in humans with polycystic ovary syndrome. The obese rats showed dissociation between glucose-stimulated plasma levels of beta-EP/beta-LP and insulin levels which may contribute to the hyperinsulinemia and insulin resistance in these animals.

Correlation between macrovascular disease as assessed by bioimpedance plethysmography and various parameters used to assess diabetic "control"

Blood flow in a segment of the leg was determined by bioimpedance plethysmography in 47 diabetic patients and in 19 normal volunteers. The blood flow through the limb, expressed as stroke volume/m2 (SV/m2), was not significantly different in the two populations. SV/m2 showed significant negative correlation with the presence of peripheral vascular disease, fasting serum cholesterol concentration, glycosylated hemoglobin (HbA1c) concentration, and the duration of diabetes. The presence or absence of retinopathy (27.7% of cases) or nephropathy (4.3% of cases) did not show strong association with the SV/m2. Neither the duration of the hypertension nor the systolic or diastolic blood pressure correlated significantly with blood flow in the extremity. These data suggest that only some of the parameters used to assess "control" of diabetic patients can be useful predictors of macrovascular as well as microvascular disease in diabetic patients.

Beta-endorphin/beta-lipotropin release and gonadotropin secretion after acute exercise in physically conditioned males

beta-endorphin (beta-EP) and beta-lipotropin (beta-LPH) concentrations were measured in the basal state and after acute exercise for 15 min or until exhaustion in 6 physically conditioned male volunteers. Serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone and prolactin were also measured in the basal state. In addition, the concentrations of the gonadotropins (LH and FSH) were determined after exercise and the gonadotropin response to gonadotropin releasing hormone was assessed before and after exercise. The data show that acute exercise stimulates the release of both beta-EP and beta-LPH which return to base-line levels within 60 min after exercise. This is in contrast to our previously described results in physically unconditioned male volunteers in whom only beta-LPH release was noted after exercise. Serum LH concentrations declined after exercise reaching nadir values between 60 to 150 min after exercise. As we previously reported in physically unconditioned male volunteers, serum FSH concentrations did not change with exercise and the gonadotropin response to LRH stimulation was uninfluenced by exercise. Serum testosterone and prolactin concentration were within the normal range for healthy adult males. We speculate that the difference in beta-EP release with exercise in physically conditioned and unconditioned males represents a difference in processing of the opioid precursor molecule (pro-opiomelanocortin, POMC) in the two groups.