Aiudi, G.

Albrizio, M.

Caira, M.

Cicirelli, V.

Forte, A.

Lacalandra, G.M.

Roscino, M.T

AIUDI, GIULIO GUIDO

ALBRIZIO, MARIA

CICIRELLI, VINCENZO

ROSCINO, MARIA TERESA

CAIRA, Michele

LACALANDRA, Giovanni Michele

Archivio istituzionale della ricerca - Università di Bari

LXVIII CONVEGNO SISVET, XI CONVEGNO AIPVET E XII CONVEGNO SIRA328HORMONAL CHANGES  DURING PROESTRUS AND ESTRUS IN THE BITCH. FOCUS ON FT3, FT4 ANDCORTISOLAiudi G.[1], Albrizio M.[1], Cicirelli V.*[1], Forte A.[1], Roscino M.T.[1], Caira M.[1], Lacalandra G.M.[1][1]Department of Emergency and Organs Transplantations, Univerity of Bari, Italy. ~ BariThe aim of this study is to evaluate serum levels of fT3, fT4 and cortisol during bitch estrous period  in orderto understand whether a crosstalk between the thyroid and the adrenal glands may modulate the breedingactivity of this species in physiological conditions.Seven healthy female dogs (age: 3.6±1.05 years; body weight: 20.8±3 kg), which had reached the 3rd heat,were included in the study. All of them, at the end of their anestrus phase, were examined twice a weekuntil the apperance of vaginal discharge (T0). During each clinical visit a vaginal cytological smear wasevaluated by Diff quik staining  and starting from T0 a blood sample, was taken. Afterwards new bloodsamples and vaginal smears were obtained at T1:  3.7±0.7 days after the onset of proestrus (P4<0.5 ng/ml);T2:  8.14±0.6 days after the beginning of proestrus (0.5 <P4< 1ng/ml); thereafter they were got at intervalsof about 48 hours.  T3: at estrus; T4: at the alleged LH peak; T5 and at the survey of the first day ofcytological diestrus (T6) after 5.14±0.6 days from T5. Each plasma sample was subjected to quantitativeassay of fT3, fT4, P4 and cortisol by enzyme immunoassay kits (EIA WELL®, Radim, Italy). Data wereanalyzed by ANOVA test.For both free thyroid hormones an increase of plasma concentration, was observed, starting from thebeginning of proestrous, with a peak at T1 more pronounced for fT3 (P<0.001), at each time considered. Anew increase at the beginning of the estrous phase was observed for fT3 (T3vsT0, T1, T4 P<0.001; andT3vsT2, P<0.01). Also fT4 showed a pick at T3 (T3vsT6 P<0.05). Subsequently, both hormones had reachedbaseline values, to increase again at T5 (fT3: T5vsT1 P<0.001);  fT4 T5vsT4 P<0.05) during the periovulatoryperiod. Another pick was recorded at T6 ((fT3: T6vsT0, T1, T4 P<0.001; vs T2 P<0.01;  fT4: T6vs T0, T1 , T3,P<0.005 ; T6vsT4 P<0.01) . Cortisol values did not show significant differences.Under physiological conditions circulating fT3 and fT4 are in continuous equilibrium, due to thehomeostatic mechanisms ensuring gradual changes in the concentrations of fT3, which is the most activethyroidal hormone (Kelly and Chopra, 2000). In our study in fact curves describing serum concentrations ofthe two hormones maintained an almost similar trend.  Peaks evidenced in proestrus  and in  estrusunderline their involvement in the mechanism regulating follicular development and ovulation (Cecconi etal., 2007; Kobayashi et al., 2009). The increased metabolic request during the estrus cycle responsible ofthe thyroid hormones rise probably does not involve the adrenal glands since cortisol concentrations donot show statistical significant variations.Cecconi S., Rucci N., Scaldaferri M.L., Moretti C. (2007). Thyroid hormone effect on mouse oocytematuration and granulosa cell aromatase activity. Endocrinology, 140: 1783-1788.Kelly G.S., Chopra I.J.(2000). An assessment of daily production and significance of thyroidal secretion of 3,3',5' triiodithyronine(reverse T3) in man. J. Clin. Invest, 58:32-40.Kobayashi N., Orisaka M., Cao M., Kotsuji F., Leader A., SakuragiN., Tsang B.K. (2009). Growth differentiation factor-9 mediates follicle-stimulating hormone-thyroidhormone interaction in the regulation of rat preantral follicular development. Endocrinology, 150:5566-74.REPRODUCTIONfT3, fT4, CORTISOL

English

HORMONAL CHANGES DURING PROESTRUS AND ESTRUS IN THE BITCH. FOCUS ON FT3, FT4 AND
CORTISOL

HORMONAL CHANGES DURING PROESTRUS AND ESTRUS IN THE BITCH. FOCUS ON FT3, FT4 AND

CORTISOL

HORMONAL CHANGES DURING PROESTRUS AND ESTRUS IN THE BITCH. FOCUS ON FT3, FT4 AND CORTISOL

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Archivio istituzionale della ricerca - Università di Bari