Anterior pitutiary and pitutiary-dependent target organ function in men infected with the human immunodeficiency virus

To evaluate pituitary and pituitary-dependent target organ function in men infected with the human immunodeficiency virus (HIV), 26 ambulatory HIV-positive men (13 with acquired immunodeficiency syndrome [AIDS]) and nine healthy control men were administered rapid sequential injections of thyrotropin (TSH)-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH), ovine corticotropin (ACTH)-releasing hormone (oCRH), and human growth hormone-(GH)-releasing hormone (hGHRH). Blood samples were collected before and for 90 minutes after the injections for immunoassay of pituitary hormones, cortisol, testosterone, and free thyroxine (fT(4)). Data were analyzed for each group of men considering basal, peak, and incremental responses to the releasing hormones, as well as the time course of response of each hormone. Mean basal serum GH concentrations were the same in all groups (control, AIDS, and non-AIDS HIV-positive), but stimulated GH levels were substantially higher at all time points in both groups of HIV-positive subjects. Results for prolactin (PRL) were similar, although stimulated PRL levels were increased significantly only in the AIDS group. The mean basal serum TSH concentration and stimulated TSH levels at 60 and 90 minutes were significantly greater in the AIDS group than in the control group. Basal mean fT(4) concentration in the AIDS group was significantly less than in the control group. Mean basal and stimulated serum (total) testosterone concentrations in all groups were the same. However, basal serum luteinizing hormone (LH) concentrations in both groups of HIV-infected men were significantly greater than in controls; stimulated (peak) LH levels were not different from control levels. Basal and peak stimulated plasma ACTH concentrations were significantly increased in both HIV-infected groups. Basal serum cortisol levels were also greater, on average, in HIV-infected groups, although stimulated (peak) cortisol responses were not different. These results indicate that basal serum concentrations of TSH, LH, ACTH, and cortisol are modestly increased in men with AIDS, and that maximum levels of GH, PRL, TSH, and ACTH stimulated by the releasing hormones are also increased in this group. Measurements obtained in the non-AIDS HIV-infected men showed a pattern generally similar to that obtained in men with AIDS, but less marked. The basis for the increased pituitary activity is unknown; we speculate that it is due to modestly impaired target organ function and to increased hypothalamic stimulation.

Long-term intermittent intravenous insulin therapy and type 1 diabetes mellitus

An important defect in insulin-dependent diabetes mellitus (IDDM) is that the liver does not meet its full fuel-processing function, because many of the enzymes involved depend on high insulin concentrations in the portal vein. We tried to reactivate the liver by long-term treatment of IDDM patients with intravenous insulin in pulses, with the aim of achieving high portal-vein concentrations during and after a glucose meal. We studied 20 IDDM patients with brittle disease; despite use of a four-injection regimen with manipulation of insulin doses, diet, and physical activity, and frequent clinic visits for at least a year, these patients still had wide swings in blood glucose and frequent hypoglycaemic reactions. The intermittent therapy consisted of 7-10 pulses of intravenous insulin, infused while the patient was ingesting carbohydrate, primarily glucose, during the first hour of a 3 h treatment; three treatments were given in a day. After 2 consecutive days' treatment, patients were treated for 1 day per week. No patient was withdrawn from the study. At the time of this analysis the duration of intermittent treatment ranged from 7 to 71 months (mean 41 [SE 5] months). Haemoglobin A1C concentrations declined from 8.5 (0.4)% at the end of the stabilisation phase to 7.0 (0.2)% at the analysis point (p = 0.0003). During the same time the frequencies of major and minor hypoglycaemic events also fell significantly (major 3.0 [1.1] to 0.1 [0], minor 13.0 [2.6] to 2.4 [0.8] per month; both p < 0.0001). Because the use of saline rather than insulin pulses would have led to unacceptable hyperglycaemia we opted for a historical control design. The absence of a true control group limits the interpretation of these preliminary results, but we believe further studies of hepatic and muscle metabolism before and after long-term intermittent intravenous insulin therapy would be worth while.

Effect of cholinergic muscarinic receptor blockade on human growth hormone (GH)-releasing hormone-(1-44)-induced GH secretion in anorexia nervosa

The presence of hypothalamic disturbances affecting GH secretion in anorexia nervosa has been suggested, although a normal GH response to GH-releasing hormone (GHRH) administration has been shown in these patients. The present study was performed to investigate the role of acetylcholine in regulating GH secretion by using pirenzepine, which selectively blocks muscarinic cholinergic receptors. Paired tests were performed in nine anorexia nervosa patients (age +/- SEM, 19.1 +/- 1.2 yr; percent ideal body weight, -32.7 +/- 2.2%) and in six normal controls (20.1 +/- 0.3 yr; -3.1 +/- 1.8%). GHRH-(1-44) (1 microgram/kg) was infused iv with and without pirenzepine pretreatment (0.6 mg/kg, iv). Basal levels of GH were not different in anorexia nervosa compared to normal controls, whereas, somatomedin-C levels were significantly lower in anorexia nervosa patients. However, after pirenzepine administration, the GHRH-stimulated GH responses were completely blocked in normal controls, but not in anorexia nervosa patients. These results suggested that altered muscarinic cholinergic mechanism are involved in the modulation of GH secretion in patients with anorexia nervosa.