ABSTRACT
Previous studies revealed that stress is a pivotal factor in the regulation of growth. Psychological harassment may result in psychosocial dwarfism with delayed puberty, short stature and depression. Growth hormone (GH) secretion is suppressed by stress, possibly via the attenuation of growth hormone-releasing hormone (GHRH) secretion. However, the morphological substrate of this phenomenon has not been elucidated yet. Since neuropeptide Y (NPY) levels in the plasma is increased by administration of various stressors, the common consensus is that NPY plays a crucial role in the stress response. In the present study, we examined the putative juxtapositions between the NPY- and GHRH-immunoreactive (IR) systems in the human hypothalamus using double-label immunohistochemistry. Our findings revealed that the majority of the GHRH-IR perikarya formed intimate associations with NPY-IR fiber varicosities. The majority of these juxtapositions were found in the infundibular nucleus/median eminence where NPY-IR fiber varicosities often covered a significant surface area of the GHRH neurons. Since the juxtapositions between the GHRH-IR perikarya and NPY-IR fiber varicosities may be functional synapses, they may represent the morphological substrate of stress-suppressed GH secretion. The large number of contacting elements indicates that NPY plays a pivotal role in GH release, and may be considered as a major factor in the attenuation of growth by stress in humans.
Subject(s)
Growth Hormone-Releasing Hormone/metabolism , Hypothalamus/cytology , Hypothalamus/metabolism , Nerve Net/metabolism , Neuropeptide Y/metabolism , Aged , Aged, 80 and over , Female , Humans , Male , Nerve Net/cytology , Neurons/cytology , Neurons/metabolism , Numerical Analysis, Computer-Assisted , Postmortem Changes , Synapses/metabolismABSTRACT
Immunoreactive oxytocin (OXT) detected in extracts of human coeliac ganglia and nn. vagi was characterized by high-performance liquid chromatography (HPLC). HPLC/RIA examinations demonstrated that a major part of the immunoreactive material in both investigated areas co-eluted with a reference synthetic OXT, but in the extracts of coeliac ganglia a second immunoreactive peak was also observed.
Subject(s)
Ganglia, Sympathetic/chemistry , Oxytocin/analysis , Vagus Nerve/chemistry , Aged , Chromatography, High Pressure Liquid/methods , Humans , Male , Middle Aged , Radioimmunoassay/methodsABSTRACT
The effects of a single injection of 20 mg/kg histamine on the immunoreactive arginine-8-vasopressin (AVP) and oxytocin (OXT) levels in the rat spinal cord were studied after peripheral (intraperitoneal) administration. Histamine induced a 60% elevation in the AVP content of the spinal cord, whereas the spinal level of OXT decreased by 36%. The findings suggest that peripheral histamine differentially affects the AVP and OXT levels in the spinal cord.
Subject(s)
Histamine/pharmacology , Oxytocin/metabolism , Spinal Cord/drug effects , Vasotocin/metabolism , Animals , Injections, Intraperitoneal , Rats , Rats, Inbred Strains , Spinal Cord/metabolismABSTRACT
Oxytocin-like immunoreactivity (IR-OXT) was detected in extracts of human spinal L5 and Gasserian ganglia by a radioimmunoassay (RIA) specific to oxytocin (OXT) and was identified by high-performance liquid chromatography (HPLC). One of the two immunoreactive peaks obtained on HPLC was found to elute at the same position as the OXT standard. The results reveal the presence of chromatographically identified OXT immunoreactivity in human sensory ganglia.
