Glucocorticoid Inhibition of Growth in Rats: Partial Reversal with Somatostatin Antibodies*

Abstract

Clinically, glucocorticoids are important immunosuppressive hormones. Yet, these steroids are also potent inhibitors of growth. We hypothesized that glucocorticoids may partially inhibit growth by increased somatostatin (SRIF) secretion. We tested this hypothesis using passive immunization techniques. Male rats (approximately 50 g) were treated daily (ip) for 33 days with saline (SAL) or dexamethasone (DEX, 40 micrograms/kg) and every fourth day with normal sheep serum (NSS) or SRIF antiserum (SRIF-ab, 0.25 ml). Body wts were recorded daily. Groups (n = 6) were: 1) SAL + NSS, 2) SAL + SRIF-ab, 3) DEX + NSS, and 4) DEX + SRIF-ab. Regression analysis of the growth curves clearly demonstrated differences in body wt gain for the four treatment groups (P less than 0.01). Final body wt of SAL + NSS treated rats was 285 +/- 5 g and 285 +/- 12 g in SAL + SRIF-ab treated rats. DEX + NSS treated rats weighed significantly less (227 +/- 4 g, P less than 0.01) than SAL-treated rats. This glucocorticoid-induced decrease in body wt was partially reversed by the concomitant treatment of rats with SRIF-ab (241 +/- 6 g, P less than 0.05). This observation leads to the conclusion that the inhibitory effect of glucocorticoids on growth may be mediated, in part, by increased SRIF secretion.

Role of photoperiod in reproductive maturation and peripubertal hormone concentrations in male collared lemmings (Dicrostonyx groenlandicus)

“…This hormone influences various metabolic processes, including lipid mobilization and glucose utilization (Granner, 1988) and may play a role in the seasonal changes in body weight and composition observed in D. groenlandicus. High glucocorticoid concentrations depress growth in rats (Wehrenberg et al, 1990), suggesting that the decrease in corticosterone associated with short-photoperiod exposure in lemmings may allow the observed increase in growth rate. The reduced corticosterone observed in animals housed in 8 h light: 16 h dark may also be involved with thermogenic adjustments.…”

Adipokines and Cardiovascular Risk in Cushing’s Syndrome

“…Of note, the duration of hypercortisolism predicted postsurgical GHD, suggesting a direct, detrimental effect of glucocorticoid excess on GH secretion [10] . This effect may be related to alterations of either GHRH [11] or somatostatin release [12] by high levels of glucocorticoids, or a direct inhibition of pituitary somatotropes by glucocorticoids [13] .…”

Effects of Short- and Long-Term Dexamethasone Treatment on Growth and Growth Hormone (GH)-Releasing Hormone (GRH)-GH-Insulin-Like Growth Factor-l Axis in Conscious Rats.

“…The animals were given daily ip injections of DEX (200 jig/O.5 ml, Decadron', Merk USA) or saline, for 1 week and 4 weeks. The body weights and tibia lengths [17] were measured at each of these observation times. Spontaneous CH secretion was examined in conscious rats treated with DEX and saline under unrestrained conditions as previously described [19].…”

“…Neutralization of SRIF secretion by SRIF anti-serum has been reported to restore the blunted CH responses to GRH in rats [17]. Hypothalamic GRH also plays an important role in regulating pulsatile CH secretion [18] so that, it is worth investigating whether hypothalamic GRH and its receptors are altered by chronic GC excess.…”