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					Title                 BLOOD LEVELS OF THYROID
                      HORMONES, CHOLESTEROL AND
                      OTHER CONSTITUENTS DURING
                      PROLACTIN INHffiITION IN HEAT-
                      STRESSED FAT-TAILED MALE
                      M.A. Alshaikh
                       Department of Animal Production, College of
Contact lnfo           Agric., King Saud University, P.O. Box 2460,
                       Riyadh 11451, Saudi Arabia.
                      Received on: 18/1/1997 Accepted on: 9/4/1997
Year of Publication
                      Alex. J. Agric Res. 42 (1): 11-21 , 1997
Type of Publication
Full Text (Yes,No)
Key words
Abstract              A control group of six fat-tailed male lambs was
                      injected subcutaneously with Iml vehicle solution of
                      40% ethanol in saline twice a day for II days. A
                      second similar group was injected, at the same time
                      as in the control group, for six days with 0.18 mg/kg
                      BW/day with the prolactin inhibitor bromocriptine;
                      the next 5 days injections were as in the control. All
                      lambs were kept under semicontrolled room
                      temperature (43.2-43.8°C) with low relative
                      humidity «8%). Bromocriptine treated lambs
                      expressed lower packed (pCY) and mean (MeY)
                      cell volumes, hemoglobin (Hb) and mean cell
                      hemoglobin (MCR) levels than the control
                      (P<0.05). Red blood cell counts (RBC) and mean
                      cell hemoglobin concentration (MCHC) did not
                      vary among the two groups. Plasma concentration
                      of total protein was increased by bromocriptine
                      treatment mainly due to the increase in albumin
                      (P<O.OI). There was a slight decrease in glucose
                      content of plasma in the treated lambs. Levels of
                      thyroxine (T4) in plasma did not change
                      significantly due to bromocriptine treatment, while
                      those of triiodothyronine (T3) were significantly
                      reduced (P<0.01). There was a marked increase in
                      cholesterol content (P<0.0l) in plasma of treated
                      lambs compared with the control. However, no
                      significant relationship between thyroid hormone
and cholesterol levels was found in either group.
However, it is hard to neglect the synergestic action
of both thyroid hormone and prolactin in rgulating
blood level of cholesterol in heat-stressed lambs.
This action was reduced or abolished when
prolactin secretion was inhibited.

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