title: Retinal amacrine cell system tyrosine hydroxylase: the development of responsiveness to light and neuroleptic drugs.
abstract: Tyrosine hydroxylase (TH) of rat retina exists in 2 states: an activated state in the light and a basal state in the dark. In the activated state the affinity of the enzyme for the pteridine cofactor is increased. Under usual laboratory lighting conditions (12 h light--dark cycle) retinal enzyme activity of the neonate begins to appear at about 11 days of age. Enzyme activity increases in response to light at about 20 days and is fully responsive to light at 25 days. If the rats are kept in total darkness instead of normal lighting the full response of the amacrine cell system to light is delayed until about 40 days of age. The administration of neuroleptic drugs results in the activation of TH in the dark. We found that the amacrine cell system responds to neuroleptic drugs before it responds to light in animals maintained in the dark from birth.
mesh_terms: D000818:Animals; D002746:Chlorpromazine / Q000494:pharmacology*; D003623:Dark Adaptation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000187:drug effects / Q000201:enzymology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*; D014796:Visual Perception / Q000187:drug effects* / Q000502:physiology
chemical_list: D014446:Tyrosine 3-Monooxygenase; D002746:Chlorpromazine