Enzymatic dissociation and short-term culture of isolated rat anterior pituitary cells for studies on the control of hormone secretion.

A convenient procedure has been developed for preparing a suspension of isolated rat anterior pituitary cells which retains responsiveness to secretagogues. Rat anterior pituitaries were dispersed with collagenase and hyaluronidase followed by mechanical dispersion by means of a Pasteur pipette. Immediately after dispersion, the cells showed only slight responses to secretagogues, whereas after short-term culture (20-22 h) in the presence of sera, the cells recovered their ability to respond to synthetic LH-releasing hormone (LHRH) and synthetic thyrotropin-releasing hormone (TRH). During a 3-h incubation, cells prepared from pituitaries of male rats released LH and FSH, or TSH and prolactin (PRL) in amounts directly related to the dose of synthetic LHRH or TRH, respectively. The minimum effective concentrations of hypophysiotropic hormones lay between 10(-10) and 10(-9)M, although it was observed that cells originating from female rats usually gave quicker and larger responses to LHRH. No significant net increase in the total hormonal content (cells + medium) of radioimmunoassayable LH or FSH in response to LHRH, or of TSH or PRL in response to TRH, was observed during the 3-h incubation period. The cells released significant amounts of PRL, TSH, and to a lesser extent, LH, in response to 1-5 X 10-3M N6,O2'-dibutyryl cyclic AMP, accompanied by remarkable elevation in total content (cells + medium) of PRL and TSH but not of LH. The response of the cells to theophylline or high [K+] was similar to that usually observed in previous hemipituitary experiments. These results demonstrate the viability of this in vitro cell system and its suitability for further study of the regulation of the secretion of pituitary hormones.     

Primary-gaze diplopia in patients with thyroid-related orbitopathy undergoing deep lateral orbital decompression with intraconal fat debulking: a retrospective analysis of treatment outcome.

Our goal was to investigate the incidence of postoperative primary gaze diplopia in patients with thyroid-related orbitopathy (TRO) undergoing deep lateral wall orbital decompression surgery with intraconal fat debulking in the Jules Stein Eye Institute over a period of 4(1/4) years. Overall 201 orbital decompression surgeries were performed in 116 patients (23 males, 93 females). All surgeries were performed by two of the authors (R.A.G. and J.D.M.) and in the noninflammatory phase of the disease. Exophthalmos decreased by an average of 3.4 +/- 2.7 mm from 23.8 +/- 3.2 mm (17-31) to 20.4 +/- 2.5 mm (14-29), p < 0.001, 95% confidence interval (CI) (3.0:3.8). 31% of patients had preoperative primary gaze diplopia and 28.4% had postoperative primary gaze diplopia. Thirty (83%) of the 36 patients with preoperative diplopia had also postoperative diplopia; 6 (16.7%) of the 36 patients had improvement in diplopia following deep lateral wall decompression. Of the 80 (69%) of patients without preoperative double vision 3 developed postoperative double vision in primary gaze (2.6% of all patients). These 3 patients were older (56 versus 46 years, p = 0.047), had more limitation in ocular movements (p = 0.017) and achieved more decrease in proptosis with surgery (6 versus 3.1 mm, p = 0.024). No complications were associated with orbital decompression. In conclusion deep lateral wall orbital decompression surgery with intraconal fat debulking is associated with a low rate (2.6%) of new-onset primary gaze diplopia. Some patients (5.2%) with preoperative diplopia actually had improvement in diplopia postoperatively. This surgery is effective in reduction of congestion and exophthalmos, and is not associated with detrimental effects on visual acuity.     

Evidence for a physiological role for oxytocin in the control of prolactin secretion

The presence of oxytocin (OT) in neuronal elements of the external layer of the median eminence and in hypophysial portal plasma suggests a role for the peptide in the control of anterior pituitary function. We have reported previously that OT stimulates PRL release in vitro; therefore, we attempted to establish evidence for a physiological PRL-releasing role for OT. Plasma OT levels rose significantly just before the PRL surges occurring during a suckling stimulus in lactating rats (10 min after pup reinstatement vs. 15 min for PRL) and 48 h after estrogen injection in ovariectomized (OVX) rats (at 1200 h vs. 1300 h). Dispersed anterior pituitary cells harvested from lactating female rats and OVX estrogen-primed rats released PRL in a specific, significant, and dose-related fashion when perifused in vitro with incubation medium containing 10(-7)-10(-9) M OT, doses similar to levels found previously in hypophysial portal plasma. Infusion of antiserum specific for OT into lactating females before pup reinstatement and into estrogen-primed OVX rats 2 h before the expected release of endogenous OT delayed and significantly reduced subsequent PRL surges compared to levels in saline-or normal rabbit serum-infused rats; however, PRL release was not completely abolished. These data indicate that OT plays a physiological role in the hypothalamic control of PRL secretion and further suggest the importance of multiple factors in coordinated regulation of PRL release.