Feeding of Nigella sativa during lactation improved serum prolactin level of hypothyroid and euthyroid rats

This study was done to investigate the effects of feeding by the hydro-alcoholic extract of Nigella sativa (NS) during lactation on prolactin level of mothers and weight gain of offspring in propylthiouracil (PTU) induced- hypothyroid and euthyroid rats. Forty pregnant rats were randomly divided into 8 groups and treated by: (1) Normal drinking water as a control group; (2) 0.005% PTU in drinking water; (3-5) 100, 200, or 400 mg/kg hydro-alcoholic extract of NS plus PTU (6-8) 100, 200 or 400 mg/ kg of the plant extract in drinking water without PTU. Mothers received the experimental treatments from the first day after delivery through the lactation period. The offspring continued to receive the experimental treatments up to the first two months of their life. PTU decreased serum thyroxin concentration of mothers and their dams compared to the control ones (P<0.001) which improved by the plant extract (P<0.001). There was no significant difference between the groups in TSH concentration. There was no significant difference between PTU and control groups in the duration of the lactation period and also in serum prolactin level. All doses of the plant extract increased the duration of lactation period of both hypothyroid and euthyroid rats compared to both control and PTU groups which were accompanied by serum prolactin concentration (P<0.001). The extract also increased the body weight gain of offspring rats (P < 0.01- P<0.001). In the present study we showed hypothyroid status induced by PTU during the lactation period did not change serum prolactin level. Administration of NS extract during lactation period improved prolactin concentrations in both hypothyroid and euthyroid rats, prolonged lactation period, and improved weight gain of the offspring.