**9.1 The effects of dorsal and ventral surgical approaches**

The unilateral perforation of the dorsal or ventral abdominal wall results in different changes in progesterone, testosterone and estradiol serum levels. Irrespective of the day of the estrous cycle surgery was performed, rats with a ventral sectioning of the abdominal wall showed higher progesterone and testosterone levels in serum than control rats and rats with dorsal sectioning of the abdominal wall (Figure 2). The increase in hormone release could be explained by an increase in StAR protein phosphorylation and/or synthesis stimulated by the neurotransmitters released by the neural terminals arriving to the ovaries and adrenals. Changes in ACTH, LH and FSH serum levels induced by sectioning the abdominal wall cannot be ruled out. Since estradiol levels were not modified, we presume that P-450 aromatase activity is not influenced by the neural information arising from the abdominal wall.

Uchida et al. (2005) showed the existence of asymmetry in the neural reflexes arising from the abdominal skin that arrive to the ovaries and affect the ovarian blood flow and the activity of the SON. Stimulating the left abdomen produced a much stronger effect on the activity of the left ovarian sympathetic nerve than stimulating the right abdomen. The magnitude of the changes in hormone levels induced by ventral or dorsal surgery depend on both, the dorsal or ventral side (left or right) of the surgery and the day of the estrous cycle when surgery is performed. These results suggest the existence of a multisynaptic neural pathway between the abdominal wall, the adrenals and the ovaries, a pathway that is mediated through the innervations of the adrenals and ovaries (Flores et al., 2008).

Hormonal and Neural Mechanisms Regulating Hormone Steroids Secretion 19

lower when surgery was performed using a dorsal approach; and an inverse result occurred

Bilateral ovariectomy and adrenalectomy modify progesterone, testosterone and estradiol serum levels depending on the day of the cycle and the surgical approach. Analyzing the effects of dorsal or ventral bilateral ovariectomy or adrenalectomy on progesterone, testosterone and estradiol levels, suggest that the stimulatory/inhibitory signals arising from the dorsal or ventral abdominal wall modifies the sensitivity of the theca interna and

The results obtained from rats with bilateral ovariectomy or adrenalectomy suggests that the ovaries mainly produce testosterone and estradiol, while the adrenals are the main producer of progesterone. The effects of bilateral adrenalectomy performed on different days of the estrous cycle on testosterone and estradiol serum levels (Flores et al., 2008) suggest that endocrine signals arising from the adrenals (corticosterone and progesterone) play a role regulating ovarian steroids release. It is possible that at the CSMG level, bilateral adrenalectomy modified the functions of the neurons originating in the SON and the nerve

ABDOMINAL WALL

BILATERAL OVARIECTOMY

SURGERY

BILATERAL

ADRENALECTOMY \*

\*

when the animals were treated on estrus (Flores et al., 2008).

granulosa cells to the hormonal signals regulating their functions.

PROGESTERONE TESTOSTERONE ESTRADIOL

Fig. 3. Comparative effects of ventral bilateral ovariectomy or ventral adrenalectomy on progesterone, testosterone and estradiol serum levels. Based on data published by Flores et al., (2008) \* p<0.05 vs. abdominal wall surgery (MANOVA followed by Tukey's test)

The acute effects of hemiovariectomy on progesterone, testosterone, estradiol, and LH concentrations in serum depends on the surgical approach and the day of the cycle when surgery is performed (Barco et al., 2003; Flores et al., 2005, 2006, 2011; Cruz et al., 2006). Figure 4 shows the comparative effects of ventral unilateral mechanical stimulation of the SON and unilateral ventral ovariectomy, performed on each day of the estrous cycle, on progesterone, testosterone and estradiol serum levels analyzed one hour after treatment. The ventral mechanical stimulation of the left or right SON of rats in estrus resulted in higher progesterone levels. While extirpating the left ovary eliminated the progesterone levels increase, extirpating the right ovary did not. Regardless of the day of the estrus cycle

of the ovarian plexus that innervate the ovaries.

\*

**9.3 The effects of unilateral ovariectomy** 

Fig. 2. Comparative effects of ventral or dorsal sectioning the abdominal wall on progesterone, testosterone, and estradiol serum levels. Based in data published by Flores et al., (2008) \* p<0.05 vs. control (MANOVA followed by Tukey's test)
