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.
Age Factors ; Aging/physiology ; Animals ; Arylalkylamine N-Acetyltransferase/*analysis/immunology/physiology ; Blotting, Western ; Dogs ; Fluorescent Antibody Technique ; Male ; Receptor, Melatonin, MT2/*analysis/immunology/physiology ; Spinal Cord/*chemistry/immunology/physiology

The present study observed the resistance to reinfection with Clonorchis sinensis in various experimental animals including mice, guinea pigs, rabbits, and dogs, as well as rats and hamsters. The resistance rates to reinfection in rats, mice, hamsters, guinea pigs, rabbits, and dogs were 79.7%, 58.0%, -12.6%, 54.8%, 62.6%, and 6.0%, respectively. Worms recovered from reinfected rats and mice were immature, and significantly smaller than those from the primarily infected (P < 0.01), whereas those from other animals were fully matured to adults. These findings indicate that the protective response against reinfection with C. sinensis is prominent in rats and mice, and that they may be a good animal model to investigate the mechanism of resistance to reinfection with C. sinensis.
Rats ; Rabbits ; Praziquantel/therapeutic use ; Mice ; Guinea Pigs ; Dogs ; Cricetinae ; Clonorchis sinensis/immunology/*physiology ; Clonorchiasis/drug therapy/immunology ; Anthelmintics/therapeutic use ; Animals, Laboratory/immunology/*parasitology ; Animals

Immunocastration is a considerable alternative to a surgical castration method especially in male animal species for alleviating unwanted male behaviors and characteristics. Induction of high titer of antibody specific for gonadotropin-releasing hormone (GnRH) correlates with the regression of testes. Fusion proteins composed of canine GnRH and T helper (Th) cell epitope p35 originated from canine distemper virus (CDV) F protein and goat rotavirus VP6 protein were produced in E. coli. When these fusion proteins were injected to male dogs which were previously immunized with CDV vaccine, the fusion protein of GnRH-CDV Th cell epitope p35 induced much higher antibody than that of GnRH-rotavirus VP6 protein or GnRH alone. The degeneration of spermatogenesis was also verified in the male dogs immunized with the fusion protein of GnRH-CDV Th cell epitope p35. These results indicate that canine GnRH conjugated to CDV Th cell epitope p35 acted as a strong immunogen and the antibody to GnRH specifically neutralized GnRH in the testes. This study also implies a potential application of GnRH-based vaccines for immunocastration of male pets.
Amino Acid Sequence ; Animals ; Antibodies/blood ; Base Sequence ; Contraception, Immunologic/methods/*veterinary ; Distemper Virus, Canine/*immunology ; Dogs/immunology/*physiology ; Epitopes, T-Lymphocyte/*immunology ; Fertility/immunology ; Gonadotropin-Releasing Hormone/chemistry/*immunology ; Male ; Molecular Sequence Data ; Organ Size ; Recombinant Proteins/immunology ; Spermatogenesis/immunology ; T-Lymphocytes, Helper-Inducer/immunology ; Testis/immunology ; Vaccines, Contraceptive/immunology