Pinealectomy reduces hepatic and muscular glycogen content and attenuates aerobic power adaptability in trained rats

Author(s)

Borges-Silva, Cristina das Neves ; Takada, Julie ; Alonso-Vale, Maria Isabel Cardoso ; Peres, Sidney B. ; Fonseca-Alaniz, Miriam H. ; Andreotti, Sandra ; Cipolla-Neto, Jose ^[7] ; Pithon-Curi, Tania C. ; Lima, Fabio Bessa

• Document type: Journal article
• Source: Journal of Pineal Research; v. 43, n. 1, p. 96-103, Aug. 2007.
• Field of knowledge: Biological Sciences - Physiology

Abstract

During the rat oestrous cycle, the afternoon of pro-oestrous is characterised by preovulatory surges of luteinising hormone (LH) and prolactin. On the afternoon of oestrous, a secretory surge of prolactin has also been reported. Because the medial preoptic area (MPOA) is known to regulate prolactin and LH secretory surges and noradrenaline has been demonstrated to stimulate these hormones release, we evaluated whether noradrenaline release in the MPOA was temporally associated with plasma prolactin and LH surges in cycling rats. During the 4 days of oestrous cycle, noradrenaline concentrations were determined in microdialysates from the MPOA, collected at 30-min intervals from 10.30 h to 19.00 h. Plasma prolactin and LH levels were measured in blood samples withdrawn hourly from 14.00 h to 19.00 h on pro-oestrous and from 13.00 h to 18.00 h on the other days of the cycle. On the afternoons of both pro-oestrous and oestrous, noradrenaline levels increased at 14.00 h and remained elevated until 16.30 h. Conversely, they were low and constant throughout metoestrous and dioestrous. Correlating with noradrenaline release in the MPOA, plasma prolactin surges occurred during the afternoons of both pro-oestrous and oestrous. On pro-oestrous, the afternoon LH surge was also preceded by the increase in MPOA noradrenaline whereas, during oestrous, LH secretion was low and unaltered. A temporal association between noradrenaline release and prolactin secretion suggests that noradrenergic neurotransmission in the MPOA regulates prolactin surges in female rats. Moreover, our data also suggest that MPOA noradrenaline requires specific conditions to physiologically regulate LH secretion, which seems to occur during the afternoon of pro-oestrous. (AU)

• FAPESP's process: 04/06767-2 - Melatonin and the control of energy metabolism: central and peripheral actions and their interaction with other hormones
• Grantee: José Cipolla Neto
• Support Opportunities: Research Projects - Thematic Grants