title: Effects of pentachlorophenol (PCP) on the pituitary and thyroidal hormone regulation in the rat.
abstract: Investigations on rats after repeated application of pentachlorophenol (PCP) should clarify whether thyroid side effects caused by this xenobiotic can be seen in a dose range which does not cause major toxic effects. Female rats of the Wistar strain were treated with 3 and 30 mg PCP/kg body wt. daily by gavage for 28 days. To assess the potential impact of impurities the study was performed both with pure and technical grade PCP at the dosage of 3 mg.kg-1.day-1, and at a level of 30 mg.kg-1.day-1 with pure PCP only. The effects in animals on normal iodine diet were compared to those in animals on a low iodine diet. No decrease of body wt. was noticed, only the liver weights were increased slightly in animals treated with 30 mg.kg-1.day-1 PCP. However distinct effects on thyroid hormones as well as on thyrotropin (TSH) were observed: a pronounced fall of circulating thyroxine (T4) and triiodothyronine (T3) levels was accompanied by lower levels of both free thyroid hormones and TSH, and the T4:T3 ratio was decreased in serum. Furthermore the intrathyroidal hormone stores were reduced. An interference of PCP at pituitary or hypothalamic level is assumed as a major mode of action. Additional effects of the test substance on peripheral conversion can be suspected.
authors.affiliation: Institut für Pharmakologie und Toxikologie, Westfälische Wilhelms-Universität Münster, Germany.
authors.forename: F W
authors.initials: FW
authors.lastname: Jekat
authors.forename: M L
authors.initials: ML
authors.lastname: Meisel
authors.forename: R
authors.initials: R
authors.lastname: Eckard
authors.forename: H
authors.initials: H
authors.lastname: Winterhoff
mesh_terms: D000284:Administration, Oral; D000818:Animals; D004032:Diet; D004334:Drug Administration Schedule; D005260:Female; D007455:Iodine / Q000008:administration & dosage / Q000172:deficiency; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D010416:Pentachlorophenol / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood / Q000378:metabolism*; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D007455:Iodine; D010416:Pentachlorophenol; D013974:Thyroxine