Effects of acute stress on the contents of catecholamines and neuropeptides in chromaffin tissues of the newborn rabbit.

The neuropeptides enkephalin (ENK), galanin (GAL) and neuropeptide Y (NPY) are abundantly expressed in the paraaortic body (PAB) and adrenal glands of the newborn rabbit. To examine whether these neuropeptides are affected by acute stress, we exposed neonatal rabbits to asphyxia, insulin-induced hypoglycemia, and reserpine. Asphyxia, caused by rebreathing for 60 min in an airtight box, reduced the content of catecholamines (CAs) in the adrenal glands and increased ENK-like immunoreactivity (-LI) in the PAB. Insulin-induced hypoglycemia reduced the content of CAs as well as ENK-LI in the adrenal glands. Reserpine caused a marked depletion of the CAs both in the PAB and in the adrenal glands. In contrast, reserpine did not cause any change in the contents of the neuropeptides in either organ. These data indicate that tissue levels of the neuropeptides GAL-LI and NPY-LI, coexisting with CA in the PAB and the adrenal glands, are not biochemically affected by asphyxia, hypoglycemia or reserpine, whereas tissue levels of ENK-LI are reduced by hypoglycemia and, to some extent, are increased by asphyxia. Furthermore, even the CAs in the PAB were unaffected by asphyxia and hypoglycemia. Also, while reserpine reduces CA content, peptide levels are unaffected.

Changes in enkephalin and neuropeptide Y-like immunoreactivity in rabbit chromaffin tissues during perinatal development.

Enkephalin-like immunoreactivity (ENK-LI), neuropeptide Y (NPY)-LI and dopamine-beta-hydroxylase (DBH)-LI were found within the chromaffin cells of both the paraaortic body and the adrenal medulla of the newborn rabbit using immunohistochemistry. Cells positive to DBH-LI were abundant in both the paraaortic body and the adrenal medulla. ENK-LI positive cells were frequent in the paraaortic body, but more sparse in the adrenal medulla. A few cells staining for NPY-LI could be detected in both organs. Some nerve fibers within these organs also contained substance P-LI and calcitonin-gene related peptide-LI. The tissue contents of ENK-LI and NPY-LI, as measured by radioimmunoassay, increased after birth in the adrenal glands and were significantly higher than the fetal levels from 1 week of age. In the paraaortic body the lowest content of ENK-LI was found around birth, whereas the content of NPY-LI was highest at that time. With advancing postnatal age, the content of ENK-LI increased, whereas the content of NPY-LI decreased. At each age, there was a higher content of ENK-LI as compared to NPY-LI in both organs. This indicates that the synthesis of ENK-LI and NPY-LI in the paraaortic body is differently regulated during perinatal development.

Multiple neuropeptide immunoreactivities in a renin-producing human paraganglioma.

BACKGROUND: A case of a renin-producing paraganglioma of adrenal origin with metastases to the retroperitoneal area, paravaginal area, and the ovary is reported with immunohistochemical findings indicating expression of multiple neuropeptide immunoreactivities. The patient was 23 years old at the time of diagnosis, and died from metastatic spread of the tumor 7 years later. METHODS: Tumor tissue was examined by light microscopy, indirect immunohistochemistry, and electron microscopy. RESULTS: The tumor tissue investigated contained several cells exhibiting opioid peptide-like immunoreactivities (i.e., enkephalin and dynorphin-like immunoreactivity [LI]). A lower number of cells displayed neuropeptide Y-, galanin-, somatostatin-, neurotensin-, substance P-, peptide histidine-isoleucine-, cholecystokinin-, renin-, and calbindin-LI. CONCLUSION: To the authors' knowledge, galanin, dynorphin, peptide histidine-isoleucine, cholecystokinin, and calbindin have not been reported previously to occur in paraganglioma, and renin has been reported to occur very rarely. A review of recent literature suggest that enkephalin-, neuropeptide Y-, and somatostatin-like immunoreactivities may be useful as diagnostic markers for paragangliomas.

Perinatal development of galanin-like immunoreactivity in chromaffin tissues of the rabbit.

We have analyzed the perinatal development of galanin-like immunoreactivity (GAL-LI) and catecholamines (CA) in the paraaortal paraganglia (PGGL) and adrenal glands. In the PGGL, the tissue content of GAL-LI was highest on the day of birth and decreased postnatally. The fetal levels were lower than at birth. In contrast, the content of CA in the PGGL increased with age. In the adrenal glands, the contents of both GAL-LI and CA also increased with age. During the first postnatal week the contents of both GAL-LI and CA in the PGGL were markedly higher than in the adrenal glands. Chromatographic analysis of GAL-LI in extracts of fetal and postnatal rabbit PGGL, respectively, indicated that most of the GAL-LI from both age groups co-eluted with synthetic porcine GAL. An additional, apparently more polar, component was also detected at both ages, which may represent a differently processed form of the peptide. The high content of GAL-LI in the PGGL at birth may reflect an enhanced synthesis associated with birth.

Galanin and neuropeptide Y in chromaffin granules from the guinea-pig.

We have examined the subcellular distribution of galanin-like immunoreactivity, neuropeptide Y-like immunoreactivity and the catecholamines noradrenaline and adrenaline in the adrenal medulla from guinea-pigs. By differential centrifugation of the adrenal medulla homogenate the neuropeptides as well as the catecholamines sedimented in a 10,000 g pellet. This pellet was resuspended and further examined in discontinuous and continuous density gradients. In the discontinuous gradient the catecholamines peaked in the heavy bottom fraction, assumed to contain chromaffin granules. Galanin-like immunoreactivity and neuropeptide Y-like immunoreactivity were also enriched in this fraction. However, both neuropeptides showed high levels of sedimentable material also in a fraction of intermediate density. In the continuous density gradient, the sum of sedimentable and soluble catecholamines showed peak values in two fractions corresponding to 1.07 and 1.47 M sucrose, respectively. The NA peak in the denser fraction was more pronounced than the corresponding A peak. Galanin-like immunoreactivity showed only one peak, in the fraction corresponding to 1.07 M sucrose. The data suggest that galanin-like immunoreactivity and neuropeptide Y-like immunoreactivity are partly stored with catecholamines in chromaffin granules. However, galanin-like immunoreactivity and neuropeptide Y-like immunoreactivity was also found in fractions lighter than those containing the bulk of the catecholamines.