Horizontal knife cuts in the suprachiasmatic area prevent hamster gonadal responses to photoperiod.
We used horizontal knife cuts near the suprachiasmatic nucleus (SCN) to investigate the route for day-length information transmission from the SCN to the paraventricular nucleus (PVN). Testicular regression was blocked in animals with knife cuts dorsal to the SCN that spanned its entire rostrocaudal extent, and in PVN-ablated animals. Misplaced cuts in the ventral preoptic area also prevented gonadal regression. These neural insults did not systematically affect the circadian control of activity rhythms. The pathway from the SCN to the pineal runs from the dorsal border of the SCN and travels through the periventricular area toward the PVN.
D000818:Animals; D001931:Brain Mapping; D006224:Cricetinae; D008027:Light; D008297:Male; D008647:Mesocricetus; D009434:Neural Pathways / Q000502:physiology; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology*; D010507:Periodicity; D010870:Pineal Gland / Q000502:physiology; D011301:Preoptic Area / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000502:physiology*; D013737:Testis / Q000502:physiology*