Sexual dimorphism of arg-vasotocin gene expressing neurons in the telencephalon and dorsal diencephalon of the domestic fowl. An immunocytochemical and in situ hybridization study

Abstract

A strong sex dimorphism in the distribution of immunoreactive arginine-vasotocin (AVT) and AVT mRNA was observed in telencephalic and dorsal diencephalic areas of the domestic fowl using immunocytochemistry and in situ hybridization. Two subgroups of immunoreactive parvocellular perikarya surrounded by dense plexus of immunoreactive fibres were found within the bed nucleus of the stria terminalis and the dorsal part of the diencephalic paraventricular region of males. No signs of immunoreactivity were observed within corresponding regions of the female brain. Instead, in females a few scattered weakly stained perikarya were observed rostrally to the level of the anterior commissure, juxtapositioned to the nucleus accumbens and the floor of the lateral ventricle. The distribution of AVT mRNA containing cell profiles fully confirmed the immunocytochemical findings. Osmotic stress induced by water deprivation for 48 h had no influence on the number of immunoreactive or AVT mRNA containing parvocellular cell bodies. However, it resulted in an increase of immunoreactive cell area in the bed nucleus of the stria terminalis and dorsal diencephalon of 5. 9 and 11.7%, respectively. We suggest that the sexually dimorphic vasotocinergic circuit may be involved in the co-ordination of behavioural and autonomic functions in response to environmental stress.

The parvocellular vasotocin system of Japanese quail: a developmental and adult model for the study of influences of gonadal hormones on sexually differentiated and behaviorally relevant neural circuits.

“…These cells are detectable by immunocytochemistry in males only. This sex difference was also confirmed at the level of VT transcripts by ISH techniques (10,11).…”

“…In galliforms, immunocytochemical studies showed that VT-ir neurons are present in the BSTm of males only and cannot be visualized in females (10,11). In the canary this difference is less extreme, and both sexes have VT-ir neurons in the BSTm, but they are present in larger numbers in males than in females (6,13).…”

“…VT-ir fibers also show a sexually dimorphic distribution in parts of the avian brain. The lateral septum of males contains a denser VT-ir innervation than the female septum in Japanese quail (17), domestic fowl (11), and the canary (6). However, this sex dimorphism was not reported for other oscine species such as the zebra finch (7).…”

“…One group is located in the mesencephalon around the nucleus rotundus (3,4), and another group containing a larger number of neurons is present within the medial part of the avian nucleus of the stria terminalis (BSTm) (Figure 1). This latter group was first identified in oscine birds (5)(6)(7)(8) and later in galliforms (4,(9)(10)(11).…”

A genetically female brain is required for a regular reproductive cycle in chicken brain chimeras

“…Sexual dimorphism in the distribution of arginine vasotocin (AVT)-or galanin-expressing neurons in chicken brain has been reported previously 26,27 . We examined the distribution of AVT mRNA-expressing neurons in the brains of WB chimeras and controls at 23-25 months and in the brains of FB chimeras at 8-11 months.…”