Effects of somatostatin antiserum on growth hormone levels in rats with periventricular lesions in the anterior hypothalamus.

To determine whether residual inhibitory control of growth hormone (GH) secretion in rats with lesions of the periventricular nucleus (PVN) and depleted median eminence content of somatostatin (SRIF) is due to SRIF, PVN-lesioned rats were treated with SRIF antiserum. Such treatment, in contrast to normal sheep serum, caused increased (P less than 0.0001) plasma GH in lesioned and control groups.

Release of growth hormone, prolactin and somatostatin during perifusion of anterior pituitary and preoptic-medial basal hypothalamus from male and female rats.

These experiments were designed to determine whether it is possible using in vitro perifusion to identify a sex difference in anterior pituitary (AP) release of growth hormone (GH) and, if so, to determine whether this difference is correlated with a sex difference in hypothalamic release or content of somatostatin (SRIF). Age-matched rats of both sexes were decapitated at approximately 09.00 h, and blood was collected for determination of non-stress plasma concentrations of GH.

Effects of periventricular lesions on the release of somatostatin during perifusion.

Hypothalamic periventricular (PV) nucleus lesions reduce median eminence (ME) SRIF content by approximately equal to 80% without affecting non-stress plasma growth hormone (GH) levels or the GH response to stress. Our aim was to study the effects of PV lesions on SRIF released during perifusion of preoptic-anterior hypothalamic (PO-AH) tissue. Female rats received anterior or posterior PV lesions; sham-lesioned and intact rats served as controls.

Loss of enhanced nocturnal growth hormone secretion in aging rhesus males.

Enhanced nocturnal release of GH is decreased with aging in man, a change that may implicate GH in a general decline in anabolic metabolism associated with aging. The aim of this study was to determine whether nonhuman primates experience an age-related reduction in plasma GH levels by comparing the 24-h patterns of GH secretion in unrestrained young and aged male rhesus monkeys. Six young (8 yr old) and six aged (22+ yr old) intact rhesus males were fitted with indwelling jugular catheters, cranial platforms, and stainless steel cable tethers.

Effects of hypothalamic periventricular lesions on pulsatile growth hormone secretion.

The purpose of this study was to determine the effects of destroying somatostatin (SRIF) neurons of the periventricular (PV) nucleus of the hypothalamus on the pulsatile pattern of growth hormone (GH) secretion in female rats. At 6-10 days after placement of PV lesions, blood samples collected every 15 min for 3-4 h showed an elevation in baseline GH levels and an increase in the amplitude of GH secretory peaks; the frequency of pulses was not affected. These changes were associated with an increase in mean integrated plasma GH levels.