In this research, concentration of thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxin (T4) and their relationship with body weight in Caucasian viper have been studied. The female Caucasian pitviper (n=26) were collected from Lar in Tehran province, the animal's body weight and length, and serum TSH, T3 and T4 levels were measured by electrochemiluminescence method during autumn, winter and summer in year 2014. The results showed T3 hormone concentration in autumn was 0.74± 0.06 nmol/Lt that was higher than its level in winter, 0.46± 0.8 Fani et al.; ARRB, 14(1): 1-9, 2017; Article no.ARRB.33828 2 nmol/Lt (P≤0.05) and no significant different with its concentration in summer 0.76 ± 0.05 nmol/Lt. The concentration of T4 hormone in autumn, 0.84±0.28 nmol/Lt was higher than winter 0.76±0.033 nmol/Lt (P≤0.19) and also summer 0.64 ±0.018 nmol/Lt (P≤0.001). TSH concentration was 0.005 nmol/Lt in autumn; reach to 0.013±0.008 nmol/Lt in winter and again 0.005 nmol/Lt in summer that shows relative increase in winter (P≤0.05). Mean body length and weight of female Caucasian vipers were 47.50±0.69 cm and 50.80±2.53 gram in autumn and 34.33±2.33 cm, 43.33±2.40 gram in winter and 51.64±1.26 cm and 64.78±3.47 gram in summer, respectively. This is indicated that Caucasian vipers' body weight is decreased in winter could be because of body fat consumption, inaccessibility to food and beginning of reduction of nutritional activity at the end of autumn compare to summer that may result to lower body weight in winter. Concentration of T3 and TSH hormone is decreased in summer and increased in winter. It seems by decreasing temperature in winter serum concentration of TSH is increased and viper`s body weight reduced (Fat consumption) to provide required energy and heat for Iranian Caucasian viper survival. So, seasonal and temperature variation has significant effect on Iran Caucasian viper`s thyroid hormones that is important for animal maintenance. Although further study is needed. Original Research Article

Steroids hormones have a basic role in animals' reproductive activity and their secretion amounts are changed during the year with animal physiological conditions. There is no study reporting Iranian female snake's hormones controlling reproductive activity. In this study the estradiol (E2) and progesterone (P4) hormones level in serum samples of 26 female Caucasian vipers were examined by electrochemiluminescence (ECL). The results show the average concentration of estradiol (E2) hormone in the autumn (157.2±47.53 nmol/ Lt) is less than the early winter (December-January), 318.33±156nmol/l (p≤0.1) and again the concentration of this hormone reduced in the summer, 188.94±33.57 nmol/Lt (p≤0.78). The average concentration of P4 hormone in the autumn was 0.45±0.14nmol/Lt and in winter was 0.96±0.57 nmol/Lt, that show increasing process (p≤0.22). The average concentration of this hormone is decreasing in the summer, 0.82±0.23 nmol/Lt as compared to the winter (p≤0.78). In the fertile snacks the amount of serums estradiol is increased during the vitellogenesis and progesterone is increased during pregnancy and the amount of these hormones is low throughout the year in unfertile snacks. According to these hormones changing during the seasons it seems that the Iranian Caucasian viper from Lar area in Tehran province, during the winter season is in the vitellogenesis phase and summer is the pregnancy time and the autumn is the time of postpartum. Although the maximum amount of progesterone is inconsistent with the winter but like this case is reported before.