Thyrotropin-releasing hormone and somatostatin inhibit each others release in vitro in the rat retina.

The effect of thyrotropin-releasing hormone (TRH), somatostatin (SS) or octreotide, an analogue of SS, on release of TRH or SS from the rat retina was studied in vitro. The retina was incubated in medium 199 (pH 7.4) with 1.0 mg/ml of bacitracin (medium) for 20 min. The amount of TRH or SS release into the medium was measured by individual radioimmunoassays. The TRH release from the rat retina was inhibited significantly in a dose-related manner by the addition of SS or octreotide. The SS release from the retina was inhibited by TRH, and the inhibitory effect of TRH on SS release from the rat retina was blocked by the addition of anti-TRH receptor antiserum immunoglobulin fraction. The findings suggest an interaction between TRH and SS in the rat retina by which the addition of one inhibits the release of the other.

Distribution of Dopamine Transporter in the Rat: an Immunohistochemical Study.

OBJECTIVE: To investigate the organ distribution of dopamine transporter (DAT) in rats by immunohistochemical method. METHODS: Dopamine transporter (DAT) was identified immunohistochemically in the tissues using specific antipeptide antiserum raised in New Zealand white rabbits immunized with a conjugate of synthetic DAT peptide (29-45) with bovine serum albumin. Immunohistochemical analysis was performed by avidin-biotin complex method. RESULTS: DAT immunoreactivity was visualized in the neural perikarya, axons and dendrites of the central nervous system, retina, adrenal medulla, Auerbach's nervous branch and Meissner's nervous branch of the stomach, small intestine and colon, anterior pituitary, and lung. When using antiserum preincubated with synthetic DAT peptide (DAT, 29-45) or hypothalamus homogenate which contains DAT, no significant stain of neurons in the hypothalamus was detected. CONCLUSION: These findings suggest that DAT is widely distributed and that the method used is valuable in studying the distribution of DAT in rats.

Effects of gamma-butyric acid on the release of thyrotropin-releasing hormone from the rat retina in vitro.

Effects of gamma-butyric acid (GABA) on the release of thyrotropin-releasing hormone (TRH) from the rat retina in vitro were studied. The rat retina was incubated in medium 199 (pH 7.4) with 1.0 mg/ml of bacitracin and 100 micrograms/ml of ascorbic acid (medium). The amount of TRH release into the medium was measured by radioimmunoassay. The TRH release from the rat retina was inhibited significantly in a dose-related manner with the addition of GABA, but not with bicuculline. The inhibitory effect of GABA on TRH release from the retina was blocked by adding bicuculline to the medium. The findings suggest that the GABAergic system inhibits TRH release from the rat retina in vitro.

Organ distribution of iodide transporter (symporter) in the rat: immunohistochemical study.

Iodide transporter/symporter (NIS) was identified immunohistochemically in rat tissues using specific antipeptide serum. Anti-NIS serum was raised in New Zealand white rabbits immunized with a conjugate of synthetic NIS peptide (39-53) with bovine serum albumin. Immunohistochemical analysis was performed by avidine-biotin complex method. NIS immunoreactivity was visualized in the thyroid gland, gastric and small intestine mucosa, anterior pituitary, adrenal medulla, pancreatic islets, kidney, chorioid plexus and several brain and spinal cord nuclei. When using antiserum preincubated with synthetic NIS peptide (39-53) or rat thyroid homogenate containing NIS, no significant stain of the thyroid gland was detected. These findings suggest that NIS is widely distributed and that the method used is suitable for studying the distribution of NIS in rats.

DISTRIBUTION OF SOMATOSTATIN RECEPTOR TYPE 3 IN THE RAT: IMMUNOHISTOCHEMICAL STUDY.

Somatostatin receptor type 3 (SSTR-3) was identified immunohistochemically in the rat tissues using specific anti-SSTR-3 serum which was raised in New Zealand white rabbits immunized with a conjugate of synthetic SSTR-3 peptide (28-41) with bovine serum albumin. Immunohistochemical analysis was performed by avidin-biotin complex method. SSTR-3 immunoreactivity was visualized in the central nervous system, anterior pituitary, gastric and duodenal mucosa, Auerbach's and Meissner's nervous branch of gastrointestinal tract, adrenal medulla, testis and pancreas. Significant staining was detected in neural perikarya, axons and dendrites. When using antiserum preincubated with synthetic SSTR-3 peptide (28-41) or rat anterior pituitary homogenate which contains SSTR-3 peptide, no significant stain of the anterior pituitary or neurons in the hypothalamus was detected. These findings suggest that SSTR-3 is widely distributed and that this method is valuable in studying the distribution of SSTR-3 in rats.