title: Hypothalamo-spinal pathways and responses to photoperiod in Syrian hamsters.
abstract: Descending projections from the hypothalamic paraventricular nucleus (PVN) to the spinal cord mediate the effects of photoperiod on the reproductive system of hamsters. To elucidate the course of these PVN efferent fibers, injections of horseradish peroxidase conjugated to either cholera toxin or wheat germ agglutinin were made into the T1-C7 region of the spinal cord of hamsters. Four sets of descending tracts were identified in males and females. Two sets of fibers originated from the medial PVN and exited the nucleus dorsally and ventrally, respectively. Most of the descending fibers, however, organized themselves into two tracts that exited the PVN laterally. In earlier experiments, destruction of these lateral pathways prevented photoperiodic responses in hamsters of both sexes.
authors.affiliation: Department of Psychology, Georgia State University, Atlanta 30303.
authors.forename: T G
authors.initials: TG
authors.lastname: Youngstrom
authors.forename: A A
authors.initials: AA
authors.lastname: Nunez
mesh_terms: D000818:Animals; D006224:Cricetinae; D005260:Female; D006651:Histocytochemistry; D006735:Horseradish Peroxidase; D008027:Light; D008297:Male; D008647:Mesocricetus; D010286:Paraventricular Hypothalamic Nucleus / Q000033:anatomy & histology* / Q000502:physiology; D010507:Periodicity; D013116:Spinal Cord / Q000033:anatomy & histology* / Q000502:physiology; D013133:Spinothalamic Tracts / Q000033:anatomy & histology* / Q000502:physiology; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins
chemical_list: D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins; D006735:Horseradish Peroxidase