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J. N. Hugues, A. Enjalbert, E. Moyse, C. Shu, M. J. Voirol, J. Sebaoun, and J. Epelbaum


The role of somatostatin (SRIF) on adenohypophysial hormone secretion in starved rats was reassessed by passive immunization. Because of the absence of pulsatile GH secretion in starved rats, the effects of the injection of SRIF antiserum on GH levels can be clearly demonstrated. To determine whether starvation modifies the sensitivity of the adenohypophysis to SRIF, we measured 125I-labelled iodo-N-Tyr-SRIF binding. There was no difference in the dissociation constant (K d) nor in the maximal binding capacity (Bmax) in fed (n = 15) and starved (n = 15) animals (K d = 0·38 ± 0·09 (s.e.m.) and 0·45 ± 0·09 nmol; Bmax = 204 ± 39 and 205 ± 30 fmol/mg protein respectively).

Administration of SRIF antiserum resulted in a dose-dependent increase in plasma concentrations of GH, TSH and prolactin. The minimal effective dose of SRIF antiserum was 50 μl for GH, 100 μl for TSH and 200 μl for prolactin.

Our results show that: (1) starvation does not modify adenohypophysial SRIF-binding sites, (2) in starved male rats endogenous SRIF exerts a negative control on prolactin secretion in vivo and (3) sensitivity to endogenous SRIF seems to be different for each hypophysial cell type.

J. Endocr. (1986) 109, 169–174

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J. R. Attali, D. Darnis, P. Valensi, C. Weisselberg, and J. Sebaoun


Perifusion of rat thyroid fragments was performed to study short-term effects of TSH, theophylline and glucagon on thyroid hormone secretion. This technique proved to be relatively convenient and sensitive, and gave reproducible results for at least 3 h, permitting precise kinetic studies of response to hormonal and pharmacological agents without any interference. There was a significant (P < 0·001) linear correlation between the log TSH concentrations over the range 20–150 mu./ml and thyroid response. A second stimulation, using the same concentration of TSH, did not differ from the first stimulation if they were separated by an active 'washing' period of only 15 min. Theophylline also had a stimulating effect and like TSH induced an early release of the hormone fraction with a peak between 2 and 4 min, but it did not potentiate the TSH effect.

Perifusion of rat thyroid fragments was found to be a useful tool for analysing dynamic effects of various substances. These effects were significant for periods of time as short as 20 min. Each thyroid preparation could be used a second time for another pharmacological or hormonal test. Our preliminary results also suggested that there was a direct glucagon effect on thyroid hormone secretion with a dose–response correlation.

J. Endocr. (1984) 102, 43–48