Influences of hypertonic and hypovolemic treatments on vasopressin response in propylthiouracil (PTU) induced hypothyroid rat and effect on supplementation with L-thyroxine.
This study was performed to investigate the effects of L-thyroxine treatment on plasma vasopressin (AVP) levels in rats with hypothyroidism induced by propylthiouracil (PTU). Animals were separated into three groups each having 6 rats: control, PTU, PTU+L-thyroxine groups. Then, the groups were further divided into 3 sub-groups including 6 rats (a; basal, b; hypertonic stimulated and c; hypovolemic stimulated). At the end of the experiments all rats were decapitated in order to obtain plasma samples for analysis in terms of Hct, osmolality, TT 3 , TT 4 and vasopressin. Haematocrit (Hct) levels were the highest in hypovolemic stimulated sub-group (P < 0.001). Osmolality levels were higher in hypertonic stimulated sub-groups (P < 0.001). Total T 3 and T 4 values were the lowest in the PTU group and the highest in the L-thyroxine treated group (P < 0.001). Plasma AVP levels were reduced by hypothyroidism. However, L-thyroxine treatment after the hypothyroidism prevented this reduction (P < 0.001). Vasopressin responses to basal, hypovolemic and hypertonic stimulations were the lowest in the PTU group (P < 0.001). The results of the present study show that basal and stimulated plasma vasopressin levels are reduced in PTU-induced hypothyroidism. However, L-thyroxine treatment following hypothyroidism prevents this reduction.
Aydin
Leyla
L
Department of Physiology, Meram Medical School, Selcuk University, Konya, Turkey.
Mogulkoc
R
R
Baltaci
A K
AK
D000818:Animals; D013956:Antithyroid Agents / Q000494:pharmacology*; D001835:Body Weight; D019587:Dietary Supplements; D006982:Hypertonic Solutions; D007037:Hypothyroidism / Q000139:chemically induced / Q000178:diet therapy / Q000503:physiopathology; D020896:Hypovolemia / Q000139:chemically induced; D008297:Male; D011441:Propylthiouracil / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013974:Thyroxine / Q000008:administration & dosage / Q000627:therapeutic use*; D014667:Vasopressins / Q000097:blood*
D013956:Antithyroid Agents; D006982:Hypertonic Solutions; D014667:Vasopressins; D011441:Propylthiouracil; D013974:Thyroxine