Sexual behaviour differentiation

Most developmental neurotoxicity studies have focused on general impairment of behaviour, but some studies have also found evidence for effects on sexual dimorphic behaviour. Hormones play a central role in central nervous system development, including the sexual differentiation of the brain. Studies on hormones and various endocrine disrupting chemicals (particularly those with estrogenic or antiandrogenic effects) have shown that the developing brain may be susceptible to disturbances in sexual behaviour. Therefore, effects on one sex but not the other should not be dismissed, but must be evaluated in the context of effects on sexual differentiation of the brain. 

HER 97] Herz R., Cahill E., Differential use of sensory information in sexual behaviour as a function of gender , Human Nature, vol. 8, pp. 275-286,1997. 

Female sexual development and behaviour in mammals occurs by default and requires no ovarian secretion, and it is only in genetic males that the testis can secrete hormones which destroy this female pattern and superimpose that of the male. Sexual differentiation is not so well defined in fish, and larval exposure to both synthetic estrogens and androgens is widely used in aquaculture to produce monosex cultures. Endocrine disruption of sexual differentiation in fish may therefore reflect both the complexity and diversity of such processes between different species. Some care is required in use of the terms hermaphrodite and sex-reversal since a true hermaphrodite has both functional testes and ovaries and a sex-reversed fish is fully functional as its final sex—both produce the appropriate viable gametes. Such functional sex-reversal is not possible in mammals, but in some species of fish it is the normal developmental pattern. In most of the cases of hermaphroditism or sex-reversal reported in the non-scientific press, there is evidence only for a few ovarian follicles within a functional testis. This may be considered as feminisation or a form of intersex, and is very clearly endocrine disruption, but it is certainly neither sex-reversal nor hermaphroditism. In some cases the terms have even been used to infer induction of a single female characteristic such as production of yolk-protein by males. 

A receptor situated on the presynaptic nerve ending which responds to the transmitter released from the same nerve ending. Also termed a presynaptic receptor. Chromosome not determinant of sexual differentiation. Behavioural method whereby a sensory stimulus is paired with a painful, distasteful or unpleasant reinforcement. In behavioural therapy this method is used to produce an association between a negative experience and undesirable behaviour. 

Evidence that both the prenatal and the postnatal sexual differentiation of the mammalian, including the human, olfactory and GnRH (gonadotropin-releasing hormone) neuronal systems may influence olfactory-genetic-neuronal-hormonal-behavioural reciprocity is found in the following ... 

Schlinger, B.A. Arnold, AJ. (1992). Plasma sex steroids and tissue aromatization in hatchling zebra fiiKhes implications for the sexual differentiation of singing behaviour Endocrinology, 130, 289-99. 

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