Effect of Adrenergic Blockade on the Pheromonal Restoration of Cyclic Activity in Young Oestrogen‐Primed Persistent Oestrous Female Rats

Abstract

The effects of adrenergic blockade on pheromonal restoration of cyclic activity were studied in acute oestrogenized persistent oestrous young female rats. Hypothalamic luteinizing hormone-releasing hormone (LHRH) and plasma LH, follicle-stimulating hormone (FSH), oestradiol and progesterone were measured by specific radio-immunoassays, and prolactin by enzyme-linked immunosorbent assay in: (i) young cycling rats; (ii) young persistent oestrous female rats; (iii) young persistent oestrous females treated with nasal sprays of male urine; and (iv) young persistent oestrous females treated with nasal sprays of male urine and injected with saline, propranolol, prazosin or yohimbine. LHRH was low 24 h after oestradiol benzoate injection, increasing up to 15 days later; LH, FSH, oestradiol and progesterone ranged from high values 24 h after oestradiol benzoate injection to low 15 days later; prolactin ranged from low concentration 24 h after oestradiol benzoate injection to high 15 days later. Male urine treatment induced a depletion of LHRH, a rise of LH, FSH and progesterone, pheromonal restoration of cyclic activity and a normal hormonal cyclic pattern. Treatment with prazosin and yohimbine prevented the pheromonal restoration of cyclic activity, the drop of LHRH and the rise of plasma concentration of the studied hormones induced by male urine, while saline or propranolol did not. These results show the hormonal pattern of the pheromonal restoration of cyclic activity in persistent oestrous rats and strongly suggest that alpha-adrenergic inputs to the hypothalamus may be involved in this pheromonal effect.

Involvement of the corticoadrenal hormones in the pheromonal restoration of reproductive activity in aging rats

“…In conclusion, the present results and the above discussed data suggest that, in aging irregularly cycling or persistent estrus female rats, nasal spraying of male urine stimulates ACTH release, which in turn, stimulates adrenal release of P and B. P of adrenal origin may have facilitated the vomeronasal-dependent LHRH release (Mora and Cabrera, 1997;Mora and Sánchez-Criado, 2002), and both P and B from the adrenal glands may have facilitated LHRH action on the puituitary, resulting in increased LH and FSH plasma levels. In turn, the released gonadotropins stimulate ovarian steroidogenesis, and the raising resulting levels of ovarian estradiol after MU exposure initiates the functional activation of the hypothalamus-pituitary-ovarian axis (Krey and Everett, 1973).…”

“…In addition, it have been stated that a single injection of ACTH leads to a rise in plasma LH and FSH levels after the rise of adrenal P (Putnam et al, 1991). Because data gleaned in recent years have shown a functional coordinated activity between the adrenal and reproductive systems (Levine, 2002), the aim of the present study was to explore the involvement of the adrenal secretory products in the early gonadotropin secretion (Mora and Sánchez-Criado, 2002) associated with the PRCA .…”

“…In these studies, aging or young estrogenized female rats in anovulatory persistent estrus or irregular cycling, show a reinitiation of estral cycles after nasal spraying of male urine (pheromonal restauration of cyclic activity -PRCA-) . PRCA is an effect mediated by the urinary pheromonal stimulation of the vomeronasal organ (Mora and Cabrera, 1997) and is preceded by an a-adrenergic-mediated release of the hypothalamic decapeptide luteinizing hormonereleasing hormone (LHRH) (Mora and Sánchez-Criado, 2002) and plasma increases of luteinizing hormone (LH), follicle stimulating hormone (FSH) estradiol (E 2 ) and progesterone (P) . Interestingly, we found that peripheral P levels in females rise earlier than those of LH and FSH after nasal spraying of male urine (Mora and Sánchez-Criado, 2002).…”

“…PRCA is an effect mediated by the urinary pheromonal stimulation of the vomeronasal organ (Mora and Cabrera, 1997) and is preceded by an a-adrenergic-mediated release of the hypothalamic decapeptide luteinizing hormonereleasing hormone (LHRH) (Mora and Sánchez-Criado, 2002) and plasma increases of luteinizing hormone (LH), follicle stimulating hormone (FSH) estradiol (E 2 ) and progesterone (P) . Interestingly, we found that peripheral P levels in females rise earlier than those of LH and FSH after nasal spraying of male urine (Mora and Sánchez-Criado, 2002). In non pregnant rats, ovarian P has two origins: the first in the evening of proestrus, where mature follicles secrete P in a strictly dependence on preovulatory release of LH (Tébar et al, 1995), and the second during diestrus, in which the corpora lutea (postovulatory luteinized follicles) secrete P autonomously (Uchida et al, 1969).…”