Azucena Valencia

Effects of sex steroids on the development of the accessory olfactory bulb in the rat: a volumetric study

The effects of postnatal (on day 1 after birth) male castration and female androgenization on accessory olfactory bulb (AOB) volume were studied. Control males showed greater values than females in AOB volume. Postnatal treatments abolished and inverted these differences. It is suggested that the AOB development is influenced by sex steroids during at least a postnatal period.

Sexual dimorphism in the bed nucleus of the accessory olfactory tract in the rat

This work investigates the existence of sex differences in the volume and number of neurons and glial cells in the bed nucleus of the accessory olfactory tract (BAOT). Males showed larger volume and number of cells than female rats. Early postnatal (day 1 after birth) orchidectomy in males, and androgenization in females, reversed these differences. No sex differences were found in BAOT glial cells. The sexual dimorphism found in the neuron/glial cell ratio reflects sex differences in neuron number. The existence of sexual dimorphism in the BAOT supports our earlier hypothesis which states that the vomeronasal system (VNS) is sexually dimorphic.

Effects of sex steroids on the development of the accessory olfactory bulb mitral cells in the rat

The effects of postnatal (on day 1 after birth) male castration and female androgenization on accessory olfactory bulb (AOB) mitral cells population were studied. Control males showed a greater number of AOB mitral cells than females. Postnatal treatments abolished and inverted these differences. It is suggested that the population of AOB mitral cells is influenced by sex steroids during at least a postnatal period.

Effects of sex steroids on the development of two granule cell subpopulations in the rat accessory olfactory bulb

The effects of postnatal male castration on day 1 (D1) after birth and female androgenization on accessory olfactory bulb (AOB) light and dark granule cell populations were studied. Control males showed a greater number of both light and dark AOB granule cells than females. Postnatal treatment reversed these differences in the light granule cells. Female androgenization on D1 does not affect the number of AOB dark granule cells. However, male orchidectomy also on D1 significantly decreases the number of dark granule cells. Androgens injected into female rats are able to increase the number of AOB dark granule cells if they are administered on D14. This suggests a different critical period for the early effects of androgens on the dark granule cells with respect to light granule cells.

Postnatal administration of dihydrotestosterone to the male rat abolishes sexual dimorphism in the accessory olfactory bulb: a volumetric study

The regulatory action of the non-aromatizable androgen dihydrotestosterone (DHT) on sexual differentiation of the volume of the rat accessory olfactory bulb (AOB) was studied. Postnatal treatment with DHT (180 micrograms/day) carried out daily between days 6 and 20 produced a drastic reduction in overall AOB size and that of its constituent neural layers in genetic males with respect to intact and control males. The volumetric measures found in DHT-treated males did not differ from those shown by the intact females. These results, which indicate a demasculinization and a feminization of the AOB volume in gonadally intact male rats induced by DHT, are discussed in relation to the presumably regulatory role of DHT on neuron populations during the sexual organizational process of the brain.

Effects of early postnatal gonadal steroids on the successive conditional discrimination reversal learning in the rat

In the present study the existence of sex differences in the acquisition, retraining and reversal of a successive conditional discrimination learning (Experiment 1) and the role of the early postnatal gonadal steroids on these discrimination tasks (Experiment 2) were investigated. In Experiment 1 two groups of experimentally naive rats (males and females) were exposed to a black-white successive conditional discrimination task in a T-maze. No sex differences were found in the acquisition or retraining. However, in the reversal phase females made fewer errors and reached the discrimination criterion (90% of correct choices) sooner than males. In Experiment 2, the absence of sex differences in the acquisition or retraining phases and the existence of sexual dimorphism in the reversal period were confirmed. In addition, female androgenization and male orchidectomy, on day one after birth, reversed the direction of the sex differences found in the successive conditional discrimination reversal learning.

Early postnatal diazepam exposure alters sex differences in the rat brain

The volume and neuron number of the sexually dimorphic accessory olfactory bulb and locus coeruleus are altered by early postnatal exposure (from the day of birth to postnatal day 16) to diazepam. After diazepam treatment, both volume and neuron number were decreased in the male accessory olfactory bulb and in the female locus coeruleus. These results indicate that early postnatal diazepam administration can bear gender-dependent teratogenic effects upon sexually dimorphic nuclei and suggest that endogenous benzodiazepines may be involved in the sexual differentiation of the brain.

Female's DHT controls sex differences in the rat bed nucleus of the accessory olfactory tract

In the present study the regulatory action of the non-aromatic androgen dihydrotestoterone (DHT) on the volume of the sexually dimorphic bed nucleus of the accessory olfactory tract (BAOT) was investigated. Postnatal treatment with DHT (180 micrograms day-1) between days 6 and 20 (D6-D20) induced, in gonadally intact male rats, a drastic reduction in the overall volume to levels typical in control females. Conversely, the postnatal administration of the anti-androgen cyproterone acetate (CA) to the females from D6-D20 produced an increment in the BAOT volume not dissimilar to that found in control males. These findings reveal that sexual organization in this vomeronasal structure is dependent on the presence of DHT in females during postnatal development.

Perinatal administration of diazepam alters sexual dimorphism in the rat accessory olfactory bulb

The present study examines the effects of pre and/or early postnatal administration of diazepam on the mitral cell and on the light and dark granule cell populations in the sexually dimorphic accessory olfactory bulb of the rat. Quantitative differences related to sex were observed in the numbers of the three types of neurons, with vehicle males showing greater numbers of cells than vehicle females. The number of mitral cells in males decreased to the levels shown by female rats following prenatal and pre-postnatal diazepam treatments, whereas the DZ treatments did not affect the females. In addition, the diazepam administration during the prenatal, postnatal and pre-postnatal periods decreased the numbers of both light and dark granule cells in males, while these two granule cell subpopulations were not affected in diazepam treated females. These results indicate that perinatal administration of diazepam can alter the sexual dimorphism in the accessory olfactory bulb and that the GABAA/benzodiazepine receptor complex is involved in the sexual differentiation this part of the brain.

Antidepressants Inhibit Enkephalin Binding to Synaptosome-Enriched Fractions of Rat Brain

Several tricyclic and nontricyclic antidepressants have been found to inhibit the binding of tritiated met-enkephalin to synaptosome-enriched fractions prepared from whole brain of rat in Tris-HCl med