Grooming behavior is an adaptation to a stressful environment that can vary in accordance with stress intensity. Direct and indirect GABA(A) receptor agonists decrease duration, frequency, incorrect transitions and uninterrupted bouts of grooming. Hormonal variation during the different phases of the estrous cycle of female rats also changes the grooming behavior. It is known that GABA(A) agonists and endogenous hormones change anxiety-like behaviors observed in the elevated plus maze test, a classical animal model of anxiety. This study was designed to determine the anxiolytic effect of clonazepam in female rats in different estrous phases and to correlate anxiety behaviors in the elevated plus maze and grooming microstructure tests. Our results show that female rats displayed higher anxiety-like behavior scores during the estrus and proestrus phases in the elevated plus maze and that clonazepam (0.25 mg/kg; i.p.) had an anxiolytic effect that was independent of the estrous phase. Grooming behaviors were higher in the proestrus phase but were decreased by clonazepam administration, independent of the estrous phase, demonstrating the anxiolytic effect of this drug in both animal models. Grooming behaviors were moderately associated with anxiolytic-like behaviors in the elevated plus maze test. Here, we describe the anxiolytic effect of clonazepam and the influence of estrous phase on anxiety. Moreover, we show that the grooming microstructure test is a useful tool for detecting anxiolytic-like behaviors in rats.
Cocaine sensitization is a marker for some facets of addiction, is greater in female
rats, and may be influenced by their sex hormones. We compared the modulatory effects
of endogenous or exogenous estradiol and progesterone on cocaine-induced behavioral
sensitization in 106 female rats. Ovariectomized female rats received progesterone
(0.5 mg/mL), estradiol (0.05 mg/mL), progesterone plus estradiol, or the oil vehicle.
Sham-operated control females received oil. Control and acute subgroups received
injections of saline, while the repeated group received cocaine (15 mg/kg,
ip) for 8 days. After 10 days, the acute and repeated groups
received a challenge dose of cocaine, after which locomotion and stereotypy were
monitored. The estrous cycle phase was evaluated and blood was collected to verify
hormone levels. Repeated cocaine treatment induced overall behavioral sensitization
in female rats, with increased locomotion and stereotypies. In detailed analysis,
ovariectomized rats showed no locomotor sensitization; however, the sensitization of
stereotypies was maintained. Only females with endogenous estradiol and progesterone
demonstrated increased locomotor activity after cocaine challenge. Estradiol
replacement enhanced stereotyped behaviors after repeated cocaine administration.
Cocaine sensitization of stereotyped behaviors in female rats was reduced after
progesterone replacement, either alone or concomitant with estradiol. The behavioral
responses (locomotion and stereotypy) to cocaine were affected differently, depending
on whether the female hormones were of an endogenous or exogenous origin. Therefore,
hormonal cycling appears to be an important factor in the sensitization of females.
Although estradiol increases the risk of cocaine sensitization, progesterone warrants
further study as a pharmacological treatment in the prevention of psychostimulant
abuse.
Exposure to a combination of caffeine and taurine improved memory and attention, and led to an imbalance in the antioxidant defence system. These results differed from those of the group that was exposed to the energy drink. This might be related to other components contained in the energy drink, such as vitamins and minerals, which may have altered the ability of caffeine and taurine to modulate memory and attention.
Alterations in GABA(A) receptor expression have been associated with the allopregnanolone (3α-hydroxy-5α-pregnan-20-one; 3α,5α-THP) antidepressant-like effect in rats. The present study aimed to verify the effect of bilateral, intra-nucleus accumbens core (intra-AcbC) administration of the neurosteroid allopregnanolone on behaviors in the forced swim and grooming microstructure tests and in the δ and γ2 GABA(A) receptor subunit mRNA expression in right and left hippocampus of rats. The results of this study showed that bilateral, intra-AcbC allopregnanolone administration (5μg/rat) presented antidepressant-like activity in the forced swim test concomitant with an increase in climbing. Allopregnanolone at doses of 1.25 and 5μg/rat also decreased the percentage of correct transitions in the grooming microstructure test. Both δ and γ2 GABA(A) subunit expressions increased in the rat hippocampus after allopregnanolone intra-AcbC treatment. Our findings point to asymmetrical GABA(A) receptor expression changes in the hippocampus of animals treated with allopregnanolone. Further investigation should evaluate the antidepressant-like effect of allopregnanolone not only in other directly infused regions but also with respect to changes in other brain areas of the limbic system to understand allopregnanolone's mechanism of action.
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