Effects of neonatal allopregnanolone manipulations and early maternal separation on adult alcohol intake and monoamine levels in ventral striatum of male rats

Early postnatal allopregnanolone levels alteration and adult behavioral disruption in rats: Implication for drug abuse

Several studies have highlighted the role that early postnatal levels of allopregnanolone play in the development of the CNS and adult behavior. Changes in allopregnanolone levels related to stress have been observed during early postnatal periods, and perinatal stress has been linked to neuropsychiatric disorders. The alteration of early postnatal allopregnanolone levels in the first weeks of life has been proven to affect adult behaviors, such as anxiety-related behaviors and the processing of sensory inputs. This review focuses on the first studies about the possible relationship between the early postnatal allopregnanolone levels and the vulnerability to abuse of drugs such as alcohol in adulthood, given that (1) changes in neonatal allopregnanolone levels affect novelty exploration and novelty seeking has been linked to vulnerability to drug abuse; (2) early postnatal administration of progesterone, the main allopregnanolone precursor, affects the maturation of dopaminergic meso-striatal systems, which have been related to novelty seeking and drug abuse; and (3) alcohol consumption increases plasma and brain allopregnanolone levels in animals and humans. Manipulating neonatal allopregnanolone by administering finasteride, an inhibitor of the 5α-reductase enzyme that participates in allopregnanolone synthesis, increases alcohol consumption and decreases the locomotor stimulant effects of low alcohol doses. At a molecular level, finasteride decreases dopamine and serotonin in ventral striatum and dopamine release in nucleus accumbens. Preliminary results suggest that serotonin 5HT3 receptors could also be affected. Although an in-depth study is necessary, evidence suggests that there is a relation between early postnatal allopregnanolone and vulnerability to drug use/abuse.

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Early postnatal AlloP levels alteration affects brain maturation and adult behavior.

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Early stress interacts to AlloP influencing neuropsychiatric disorders vulnerability.

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Fluctuations in neonatal AlloP levels play a role in alcohol abuse vulnerability.

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Neonatal finasteride induces novelty-seeking profile and increases ethanol intake.

Sex hormones in alcohol consumption: a systematic review of evidence

Sex hormones play an important role in establishing sex‐distinctive brain structural and functional variations that could contribute to the sex differences in alcohol consumption behavior. Here, we systematically reviewed articles that studied sex hormone impacts on alcohol consumption and alcohol use disorder (AUD). An extensive literature search conducted in MEDLINE, PubMed, Scopus and CINAHL databases identified 776 articles, which were then evaluated for pre‐specified criteria for relevance and quality assurance. A total of 50 articles, including 19 human studies and 31 animal studies, were selected for this review. Existing evidence supports the association of increased testosterone level and increased risk for alcohol use and AUD in males but results are inconclusive in females. In contrast, the evidence supports the association of increased estrogen level and increased alcohol use in females, with mixed findings reported in males. Much less is known about the impact of progestins on alcohol use and misuse in human subjects. Future observational and experimental studies conducted in both sexes with a comprehensive hormone panel are needed to elucidate the impact of the interplay between various sex hormone levels during various developmental stages on alcohol use‐related phenotypes and AUD.

Early post-natal neuroactive steroid manipulation modulates ondansetron effects on initial periods of alcohol consumption in rats

Neuroactive steroids (NS) such as allopregnanolone are crucial for brain development and adult behaviour. Early post-natal alterations of NS by administering finasteride induce a decrease in the sensitivity to stimulant effects of low alcohol doses, an increase in alcohol consumption, and a decrease in ventrostriatal dopamine and serotonin levels. The aim of the present study is to observe if the effects of the 5HT3 receptor antagonist ondansetron on initial alcohol consumption are modulated by post-natal NS manipulation. For this purpose, allopregnanolone, finasteride, or vehicle was injected from day 5 to 9. In adulthood, a novel object preference test was carried out in order to detect a possible novelty-seeking pattern in our animals, which has been related to vulnerability to drug abuse. The subjects then had access to two bottles (alcohol or control solutions) one hour daily for two consecutive weeks. Ondansetron (0.01 mg/kg, 0.1 mg/kg or vehicle) was administered before the hour of consumption in the initial phase (days 1, 2, 3) of the procedure, and after prolonged alcohol intake (days 11, 12, 13). Results indicated that finasteride animals showed a higher preference to explore the new object, as well as a higher alcohol consumption than the rest of the groups. Moreover, 0.1 mg/kg of ondansetron decreased alcohol consumption, but only in the post-natal finasteride group, suggesting a possible increase in 5HT3 receptor sensitivity in these animals. In conclusion, NS manipulation in crucial stages of development, such as early post-natal periods, seems to play an important role on the effects of ondansetron on alcohol intake and in the vulnerability to develop drug use or abuse.

Neonatal finasteride administration decreases dopamine release in nucleus accumbens after alcohol and food presentation in adult male rats

Endogenous levels of the neurosteroid (NS) allopregnanolone (AlloP) during neonatal stages are crucial for the correct development of the central nervous system (CNS). In a recent work we reported that the neonatal administration of AlloP or finasteride (Finas), an inhibitor of the enzyme 5α-reductase needed for AlloP synthesis, altered the voluntary consumption of ethanol and the ventrostriatal dopamine (DA) levels in adulthood, suggesting that neonatal NS manipulations can increase alcohol abuse vulnerability in adulthood. Moreover, other authors have associated neonatal NS alterations with diverse dopaminergic (DAergic) alterations. Thus, the aim of the present work is to analyse if manipulations of neonatal AlloP alter the DAergic response in the nucleus accumbens (NAcc) during alcohol intake in rats. We administered AlloP or Finas from postnatal day (PND) 5 to PND9. At PND98, we measured alcohol consumption using a two-bottle free-choice model (ethanol 10% (v/v)+glucose 3% (w/v), and glucose 3% (w/v)) for 12 days. On the last day of consumption, we measured the DA and 3,4-dihydroxyphenylacetic acid (DOPAC) release in NAcc in response to ethanol intake. The samples were obtained by means of in vivo microdialysis in freely moving rats, and DA and DOPAC levels were determined by means of high-performance liquid chromatography analysis (HPLC). The results revealed that neonatal Finas increased ethanol consumption in some days of the consumption phase, and decreased the DA release in the NAcc in response to solutions (ethanol+glucose) and food presentation. Taken together, these results suggest that neonatal NS alterations can affect alcohol rewarding properties.