Comparison of arylalkylamine N-acetyltransferase and melatonin receptor type 1B immunoreactivity between young adult and aged canine spinal cord

Melatonin affects diverse physiological functions through its receptor and plays an important role in the central nervous system. In the present study, we compared immunoreactivity patterns of arylalkylamine N-acetyltransferase (AANAT), an enzyme essential for melatonin synthesis, and melatonin receptor type 1B (MT2) in the spinal cord of young adult (2~3 years) and aged (10~12 years) beagle dogs using immunohistochemistry and Western blotting. AANAT-specific immunoreactivity was observed in the nuclei of spinal neurons, and was significantly increased in aged dog spinal neurons compared to young adult spinal neurons. MT2-specific immunoreactivity was found in the cytoplasm of spinal neurons, and was predominantly increased in the margin of the neuron cytoplasm in aged spinal cord compared to that in the young adult dogs. These increased levels of AANAT and MT2 immunoreactivity in aged spinal cord might be a feature of normal aging and associated with a feedback mechanism that compensates for decreased production of melatonin during aging.

Comparison of alpha-synuclein immunoreactivity in the spinal cord between the adult and aged beagle dog / 한국실험동물학회지

Alpha-synuclein (alpha-syn) is a presynaptic protein that is richly expressed in the central and peripheral nervous systems of mammals, and it is related to the pathogenesis of Parkinson's disease and other neurodegenerative disorders. In the present study, we compared the distribution of the immunoreactivity of alpha-syn and its related gliosis in the spinal cord of young adult (2-3 years) and aged (10-12 years) beagle dogs. We discovered that alpha-syn immunoreactivity was present in many neurons in the thoracic level of the aged spinal cord, however, its protein level was not distinct inform that of the adult spinal cord. In addition, ionized calcium-binding adapter molecule-1 (a marker for microglia) immunoreactivity, and not glial fibrillary acidic protein (a marker for astrocytes) immunoreactivity, was somewhat increased in the aged group compared to the adult group. These results indicate that alpha-syn immunoreactivity was not dramatically changed in the dog spinal cord during aging.

Decrease in Zinc Concentration in the Rat Spinal Gray Matter Induced by Peripheral Nerve Ligation, and its Relations with Increased Pain Threshold / 대한해부학회지

This study was designed to investigate any correlation between the mechanism of pain development and changes of histochemically-reactive zinc contents in the rat spinal cords following peripheal nerve ligation. Male Sprague-Dawley rats (270 ~290 g) were used for this study. We ligated a left-sided lumbar spinal nerve with silk under anesthesia using pentobarbital (50 mg/kg). Semmes-Weinstein monofilaments (Stoelting Company, Wood Dale, IL) was used to test for mechanical hyperalgesia. 30 micrometer-thick spinal cord cryosections were stained by automet-allography (Danscher, 1981). The density of zinc was significantly decreased in zinc concentration in the dorsal horn of 4th, 5th and 6th lumbar segments at 5 and 10 days after the spinal nerve ligation. Here, zinc depletion was apparent in superficial gray matter, especially layer III-IV. In addition the nerve ligated rats showed lower pain threshold. This increased pain sensation might be related with lowered vesicular zinc level in the superficial gray matter in the spinal cord. The present findings offer a proposed link between zinc and pain. Our interpretation is that there may be an extension of fine primary afferent fibers into lamina III and possibly lamina IV following peripheral nerve ligation. If further work bears out this conclusion, this would provide a possible explanation for the chronic pain states that sometimes follow peripheral nerve damage.

THE CYTOARCHITECTONIC ORGANIZATION OF THE SPINAL CORD IN THE RABBIT / 解剖学报

Fourteen adult and immature rabbits were used for the study of laminar scheme of the gray matter in the spinal cord. The spinal sections were cut transversally or sagitally into 80 ?m, 60 ?m, 15?m, and 2?m-thick sections. The sections were stained with toluidine blue or crecyl fast violet for cell body and with Luxol fast blue for myelin sheath. 2?m-thick sections were only stained with pphenylenediamine. In addition, the spinal sections from 2 cases of the animals were treated histochemically for demonstrating AChE activity. According to the Rexed's principle lamination for the cat, we have found that the cytoarchitectonic organization of the rabbit spinal cord was found to be basically similar to that of the cat except for some differences about the extension and structures of the laminae.